Patent Publication Number: US-11051016-B2

Title: Image processing device and method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of National Stage application Ser. No. 13/516,856 filed Jun. 18, 2012, which is a National Stage Entry of International Patent Application No. PCT/JP2010/072735 filed Dec. 17, 2010, claiming priority to Japanese Patent Application No. 2009-295783 filed Dec. 25, 2009 and Japanese Patent Application No. 2010-001745 filed Jan. 7, 2010, all of which are herein incorporated by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to an image processing device and method, and specifically relates to an image processing device and method which improves encoding efficiency by removing mosquito noise. 
     BACKGROUND ART 
     In recent years, there have come into widespread use devices which subject an image to compression encoding by employing an encoding format handling image information as digital signals, and at this time compress the image by orthogonal transform such as discrete cosine transform or the like and motion compensation, taking advantage of redundancy peculiar to the image information, in order to perform highly effective information transmission and storage at that time. Examples of this encoding method include MPEG (Moving Picture Expert Group) and so forth. 
     In particular, MPEG2 (ISO/IEC 13818-2) is defined as a general-purpose image encoding format, and is a standard encompassing both of interlaced scanning images and sequential-scanning images, and standard resolution images and high definition images. For example, MPEG2 has widely been employed now by broad range of applications for professional usage and for consumer usage. By employing the MPEG2 compression format, a code amount (bit rate) of 4 through 8 Mbps is allocated in the event of an interlaced scanning image of standard resolution having 720×480 pixels, for example. Also, by employing the MPEG2 compression format, a code amount (bit rate) of 18 through 22 Mbps is allocated in the event of an interlaced scanning image of high resolution having 1920×1088 pixels, for example. Thus, a high compression rate and excellent image quality can be realized. 
     With MPEG2, high image quality encoding adapted to broadcasting usage is principally taken as an object, but a lower code amount (bit rate) than the code amount of MPEG1, i.e., an encoding format having a higher compression rate is not handled. According to spread of personal digital assistants, it has been expected that needs for such an encoding format will be increased from now on, and in response to this, standardization of the MPEG4 encoding format has been performed. With regard to an image encoding format, the specification thereof was confirmed as an international standard as ISO/IEC 14496-2 in December in 1998. 
     Further, in recent years, standardization of a standard called H.26L (ITU-T Q6/16 VCEG) has progressed, originally intended for image encoding for videoconferencing usage. With H.26L, it has been known that as compared to a conventional encoding format such as MPEG2 or MPEG4, though greater computation amount is requested for encoding and decoding thereof, higher encoding efficiency is realized. Also, currently, as part of activity of MPEG4, standardization for also taking advantage of functions not supported by H.26L with this H.26L taken as a base, to realize higher encoding efficiency, has been performed as Joint Model of Enhanced-Compression Video Coding. As a schedule of standardization, H.264 and MPEG-4 Part 10 (Advanced Video Coding, hereafter, referred to as 264/AVC) become an international standard in March, 2003. 
       FIG. 1  is a block diagram illustrating a configuration example of an image encoding device with a compressed image based on H.264/AVC as output. 
     With the example in  FIG. 1 , the image encoding device  1  has an A/D conversion unit  11 , a screen rearranging buffer  12 , a computing unit  13 , an orthogonal transform unit  14 , a quantization unit  15 , a lossless encoding unit  16 , and a storage buffer  17 , an inverse quantization unit  18 , an inverse orthogonal transform unit  19 , a computing unit  20 , a deblocking filter  21 , frame memory  22 , a switch  23 , an intra prediction unit  24 , a motion prediction/compensation unit  25 , a prediction image selecting unit  26 , and a rate control unit  27 . 
     The A/D conversion unit  11  performs A/D conversion of an input image, and outputs to the screen rearranging buffer  12  and stores. The screen rearranging buffer  12  rearranges the images of frames in the stored order for display into the order of frames for encoding according to GOP (Group of Picture). 
     The computing unit  13  subtracts, from the image read out from the screen rearranging buffer  12 , the prediction image from the intra prediction unit  24  or the prediction image from the motion prediction/compensation unit  25 , selected by the prediction image selecting unit  26 , and outputs difference information thereof to the orthogonal transform unit  14 . The orthogonal transform unit  14  subjects the difference information from the computing unit  13  to orthogonal transform, such as discrete cosine transform, Karhunen-Loéve transform, or the like, and outputs a transform coefficient thereof. The quantization unit  15  quantizes the transform coefficient that the orthogonal transform unit  14  outputs. 
     The quantized transform coefficient serving as the output of the quantization unit  15  is input to the lossless encoding unit  16 , and subjected to lossless encoding, such as variable length coding, arithmetic coding, or the like, and thus compressed. 
     The lossless encoding unit  16  obtains information indicating intra prediction from the intra prediction unit  24 , and obtains information indicating an inter prediction mode, and so forth from the motion prediction/compensation unit  25 . Note that the information indicating intra prediction, and the information indicating inter prediction will also be referred to as intra prediction mode information and inter prediction mode information, respectively, hereinafter. 
     The lossless encoding unit  16  encodes the quantized transform coefficient, and also encodes the information indicating intra prediction, information indicating inter prediction mode, and so forth, and takes these as part of header information in a compressed image. The lossless encoding unit  16  supplies the encoded data to the storage buffer  17  for storing. 
     For example, with the lossless encoding unit  16 , lossless encoding processing, such as variable length coding, arithmetic coding, or the like, is performed. Examples of the variable length coding include CAVLC (Context-Adaptive Variable Length Coding) stipulated by the H.264/AVC format. Examples of the arithmetic coding include CABAC (Context-Adaptive Binary Arithmetic Coding). 
     The storage buffer  17  outputs the data supplied from the lossless encoding unit  16  to a decoding side, for example, such as a recording device or transmission path or the like downstream not shown in the drawing, as a compressed image encoded by the H.264/AVC format. 
     Also, the quantized transform coefficient output from the quantization unit  15  is also input to the inverse quantization unit  18 , inversely quantized, and then further subjected to inverse orthogonal transform at the inverse orthogonal transform unit  19 . The output subjected to inverse orthogonal transform is added to the prediction image supplied from the prediction image selecting unit  26  by the computing unit  20 , and becomes a locally decoded image. The deblocking filter  21  removes block noise of the decoded image, and then supplies to the frame memory  22  for storing. An image prior to being subjected to deblocking filter processing by the deblocking filter  21  is also supplied to the frame memory  22  for storing. 
     The switch  23  outputs a reference image stored in the frame memory  22  to the motion prediction/compensation unit  25  or intra prediction unit  24 . 
     With this image encoding device  1 , for example, the I picture, B picture, and P picture from the screen rearranging buffer  12  are supplied to the intra prediction unit  24  as an image to be subjected to intra prediction (also referred to as intra processing). Also, the B picture and P picture read out from the screen rearranging buffer  12  are supplied to the motion prediction/compensation unit  25  as an image subjected to inter prediction (also referred to as inter processing). 
     The intra prediction unit  24  performs intra prediction processing of all of the candidate intra prediction modes based on the image to be subjected to intra prediction read out from the screen rearranging buffer  12 , and the reference image supplied from the frame memory  22 , to generate a prediction image. 
     At that time, the intra prediction unit  24  calculates a cost function value as to all of the candidate intra prediction modes, and selects an intra prediction mode wherein the calculated cost function value provides the minimum value, as the optimal intra prediction mode. 
     The intra prediction unit  24  supplies the prediction image generated in the optimal intra prediction mode, and the cost function value thereof to the prediction image selecting unit  26 . In the event that the prediction image generated in the optimal intra prediction mode has been selected by the prediction image selecting unit  26 , the intra prediction unit  24  supplies information indicating the optimal intra prediction mode to the lossless encoding unit  16 . The lossless encoding unit  16  encodes this information, and takes this as part of the header information in the compressed image. 
     The image subjected to inter processing read out from the screen rearranging buffer  12 , and the reference image are supplied from the frame memory  22  to the motion prediction/compensation unit  25  via the switch  23 . The motion prediction/compensation unit  25  performs motion prediction of a block in all of the candidate inter prediction modes to generate the motion vector of each block. 
     The motion prediction/compensation unit  25  uses the predicted motion vector of each block to calculate a cost function value as to all of the candidate inter prediction modes. The motion prediction/compensation unit  25  determines, of the calculated cost function values, the prediction mode of a block that provides the minimum value as the optimal inter prediction mode. 
     The motion prediction/compensation unit  25  supplies the prediction image of a block to be processed of the determined optimal inter prediction mode, and the cost function value thereof to the prediction image selecting unit  26 . In the event that the prediction image of the block to be processed of the optimal inter prediction mode has been selected by the prediction image selecting unit  26 , the motion prediction/compensation unit  25  outputs information indicating the optimal inter prediction mode (inter prediction mode information) to the lossless encoding unit  16 . 
     At this time, the motion vector information, reference frame information, and so forth are also output to the lossless encoding unit  16 . The lossless encoding unit  16  also subjects the information from the motion prediction/compensation unit  25  to lossless encoding processing such as variable length coding, arithmetic coding, or the like, and inserts into the header portion of the compressed image. 
     The prediction image selecting unit  26  determines the optimal prediction mode out of the optimal intra prediction mode and optimal inter prediction mode based on each cost function value output from the intra prediction unit  24  or motion prediction/compensation unit  25 . The prediction image selecting unit  26  then selects the prediction image of the determined optimal prediction mode, and supplies to the computing units  13  and  20 . At this time, the prediction image selecting unit  26  supplies selection information of the prediction image to the intra prediction unit  24  or motion prediction/compensation unit  25 . 
     The rate control unit  27  controls a rate of the quantization operation of the quantization unit  15  based on the compressed image stored in the storage buffer  17  so as not to cause overflow nor underflow. 
       FIG. 2  is a block diagram illustrating a configuration example of an image decoding device corresponding to the image encoding device in  FIG. 1 . 
     With the example in  FIG. 2 , the image decoding device  31  is configured of a storage buffer  41 , a lossless decoding unit  42 , an inverse quantization unit  43 , an inverse orthogonal transform unit  44 , a computing unit  45 , a deblocking filter  46 , a screen rearranging buffer  47 , a D/A conversion unit  48 , frame memory  49 , a switch  50 , an intra prediction unit  51 , a motion compensation unit  52 , and a switch  53 . 
     The storage buffer  41  stores the transmitted compressed image. The inverse decoding unit  42  decodes information encoded by the lossless encoding unit  16  in  FIG. 1  supplied from the storage buffer  41  with a format corresponding to the encoding format of the lossless encoding unit  16 . The inverse quantization unit  43  inversely quantizes the image decoded by the lossless decoding unit  42  with a format corresponding to the quantization format of the quantization unit  15  in  FIG. 1 . The inverse orthogonal transform unit  44  subjects to inverse orthogonal transform the output of the inverse quantization unit  43  with a format corresponding to the orthogonal transform format of the orthogonal transform unit  14  in  FIG. 1 . 
     The output subjected to inverse orthogonal transform is added to the prediction image supplied from the switch  53  from the computing unit  45  and decoded. The deblocking filter  46  removes block noise of the decoded image, then supplies to the frame memory  49  for storing, and also outputs to the screen rearranging buffer  47 . 
     The screen rearranging buffer  47  performs rearranging of images. Specifically, the order of frames rearranged for encoding order by the screen rearranging buffer  12  in  FIG. 1  is rearranged into the original display order. The D/A conversion unit  48  subjects the image supplied from the screen rearranging buffer  47  to D/A conversion, output to an unshown display for display. 
     The switch  50  reads out an image to be subjected to inter processing, and an image to be referenced from the frame memory  49 , outputs to the motion compensation unit  52 , and also reads out an image to be subjected to intra prediction from the frame memory  49 , and supplies to the intra prediction unit  51 . 
     Information indicating the intra prediction mode obtained by decoding the header information is supplied from the lossless decoding unit  42  to the intra prediction unit  51 . The intra prediction unit  51  generates a prediction image based on this information, and outputs the generated prediction image to the switch  53 . 
     Of the information obtained by decoding the header information, the inter prediction mode information, motion vector information, reference frame information, and so forth are supplied from the lossless decoding unit  42  to the motion compensation unit  52 . The inter prediction mode information is transmitted for each macroblock. The motion vector information and reference frame information is transmitted for each block to be processed. 
     The motion compensation unit  52  uses the motion vector information, reference frame information, and so forth supplied from the lossless decoding unit  42  in the prediction mode that the inter prediction mode information supplied for the lossless decoding unit  42  indicates to generate pixel values of the prediction image corresponding to the block to be processed. The generated pixel values of the prediction image are supplied to the computing unit  45  via the switch  53 . 
     The switch  53  selects the prediction image generated by the motion compensation unit  52  or intra prediction unit  51 , and supplies to the computing unit  45 . 
     Further, as an extension of this H.264/AVC, standardization of FRExt (Fidelity Range Extension) including a coding tool necessary for business use such as RGB, 4:2:2, or 4:4:4, 8×8DCT and quantization matrix stipulated by MPEG-2 has been completed in February in 2005. Thus, H.264/AVC can be used as an encoding format capable of suitably expressing even film noise included in movies, and has come to be employed for wide ranging applications such as Blu-Ray Disc (registered trademark) and so forth. 
     However, nowadays, needs for further high-compression encoding have been increased, such as intending to compress an image having around 4000×2000 pixels, which is quadruple of a high-vision image, or alternatively, needs for further high-compression encoding have been increased, such as intending to distribute a high-vision image within an environment with limited transmission capacity like the Internet. Therefore, with the above-mentioned VCEG (=Video Coding Expert Group) under the control of ITU-T, studies relating to improvement of encoding efficiency have continuously been performed. 
     As a technique for improving such encoding efficiency, a technique called an adaptive loop filter (ALF (Adaptive Loop Filter)) has been proposed in PTL 1. 
       FIG. 3  is a block diagram illustrating a configuration example of an image encoding device to which an adaptive loop filter has been applied. Note that, with the example in  FIG. 3 , for convenience of description, the A/D conversion unit  11 , screen rearranging buffer  12 , storage buffer  17 , switch  23 , intra prediction unit  24 , prediction image selecting unit  26 , and rate control unit  27  in  FIG. 1  are omitted. Also, an arrow and so forth are also omitted. Accordingly, in the case of the example in  FIG. 3 , the reference image from the frame memory  22  is directly input to the motion prediction/compensation unit  25 , and the prediction image from the motion prediction/compensation unit  25  is directly output to the computing units  13  and  20 . 
     Specifically, the image encoding device  61  in  FIG. 3  differs from the image encoding device  1  in  FIG. 1  only in that an adaptive loop filter  71  is added between the deblocking filter  21  and frame memory  22 . 
     The adaptive loop filter  71  perform calculation of an adaptive loop filter coefficient so as to minimize residual error with the original image from the screen rearranging buffer  12  (drawing is omitted), and uses this adaptive loop filter coefficient to perform filter processing on the decoded image from the deblocking filter  21 . As for this filter, a Wiener filter (Wiener Filter) is employed, for example. 
     Also, the adaptive loop filter  71  transmits the calculated adaptive loop filter coefficient to the lossless encoding unit  16 . The lossless encoding unit  16  performs lossless encoding processing such as variable length coding, arithmetic coding, or the like on this adaptive loop filter coefficient, and inserts into the header portion of the compressed image. 
       FIG. 4  is a block diagram illustrating a configuration example of an image decoding device corresponding to the image encoding device in  FIG. 3 . Note that, with the example in  FIG. 4 , for convenience of description, the storage buffer  41 , screen rearranging buffer  47 , D/A conversion unit  48 , switch  50 , intra prediction unit  51 , and switch  53  in  FIG. 2  are omitted. Also, an arrow and so forth are also omitted. Accordingly, in the case of the example in  FIG. 4 , the reference image from the frame memory  49  is directly input to the motion compensation unit  52 , and the prediction image from the motion compensation unit  52  is directly output to the computing unit  45 . 
     Specifically, the image decoding device  81  in  FIG. 4  differs from the image decoding device  31  in  FIG. 2  only in that an adaptive loop filter  91  is added between the deblocking filter  46  and frame memory  49 . 
     An adaptive loop filter coefficient decoded at the lossless decoding unit  42  and extracted from the header is supplied to the adaptive loop filter  91 . The adaptive loop filter  91  uses the supplied filter coefficient to perform filter processing on the decoded image from the deblocking filter  46 . As for this filter, a wiener filter is employed, for example. 
     Thus, the image quality of a decoded image can be improved, and further the image quality of a reference image can also be improved. 
     Now, with the above H.264/AVC format, the macroblock size is 16×16 pixels. However, the macroblock size of 16×16 pixels is not optimal for large image frames such as UHD (Ultra High Definition; 4000×2000 pixels) which will be handled by next-generation encoding formats. 
     Therefore, with NPL 2 and so forth, there has been proposed enlarging the macroblock size to a size of such as 32×32 pixels, for example. 
     CITATION LIST 
     Non Patent Literature 
     
         
         NPL 1: Takeshi. Chujoh, et al., “Block-based Adaptive Loop Filter” ITU-T SG16 Q6 VCEG Contribution, AI18, Germany, July, 2008 
         NPL 2: “Video Coding Using Extended Block Sizes”, VCEG-AD09, ITU-Telecommunications Standardization Sector STUDY GROUP Question 16—Contribution 123, January 2009. 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     Now, as image quality deterioration that may be caused at the time of performing encoding of block basis such as MPEG, mosquito noise (distortion) can be referenced as well as block noise (distortion). With the image encoding device  1  in  FIG. 1  and the image decoding device  31  in  FIG. 2 , though block noise can be removed within a motion compensation loop by the deblocking filter  21 , it is difficult to remove mosquito noise. 
     Further, as described in NPL 2, with a macroblock having a greater size than the conventional H.264/AVC format such as 32×32 pixels, 64×64 pixels, or the like, for example, in the event of orthogonal transform in 16×16 pixel increments being employed, this mosquito noise may occur more markedly with regard to image quality. 
     The present invention has been made in the light of such a situation, and according to the present invention, encoding efficiency can be improved by removing mosquito noise. 
     Solution to Problem 
     An image processing device according to a first aspect of the present invention includes: filter processing means configured to perform, within a motion compensation loop of an image, filter processing for removing mosquito noise on a macroblock to be processed in the image under control according to an orthogonal transform size and syntax elements in encoding information of the macroblock; and encoding means configured to encode the image and the encoding information. 
     The syntax elements in the encoding information may include the generated code amount and quantization scale as to the macroblock. 
     The filter processing means may include: threshold determining means configured to determine a threshold according to the orthogonal transform size of the macroblock; difficulty level parameter calculating means configured to calculate a difficulty level parameter of the macroblock using information relating to the generated code amount and quantization scale as to the macroblock; and filter processing control means configured to perform control so as to perform the filter processing on the macroblock in the case that the difficulty level parameter calculated by the difficulty level parameter calculating means is greater than the threshold determined by the threshold determining means. 
     The threshold may include an offset value that a user can set. 
     The filter processing means may use generation bits as information relating to the generated code amount. 
     The filter processing means may use a generation bit or generation bin as information relating to the generated code amount in the case that CABAC is used as a lossless encoding format. 
     The syntax elements in the encoding information may include a quantization parameter in the macroblock, and the number of non-zero orthogonal transform coefficients after quantization. 
     The filter processing means may include: threshold determining means configured to determine a threshold according to the orthogonal transform size and quantization parameter of the macroblock; and filter processing control means configured to perform control so as to perform the filter processing on the macroblock in the case that the number of non-zero orthogonal transform coefficients after quantization in the macroblock is greater than the threshold determined by the threshold determining means. 
     The threshold may include an offset value that a user can set. 
     The syntax elements in the encoding information may include motion vector information as to the macroblock. 
     The filter processing means may perform smoothing processing using a two-dimensional filter having a predetermined window size with a pixel to be processed as the center regarding a pixel value included in the macroblock as the filter processing. 
     An image processing method according to the first aspect of the present invention includes the steps of: performing, with filter processing means of an image processing device, within a motion compensation loop of an image, filter processing for removing mosquito noise on a macroblock to be processed in the image under control according to an orthogonal transform size and syntax elements in encoding information of the macroblock; and encoding, with encoding means, the image and the encoding information. 
     With the first aspect of the present invention, within a motion compensation loop of an image, filter processing for removing mosquito noise is performed on a macroblock to be processed in the image under control according to the orthogonal transform size of the macroblock, and the image and the encoding information are encoded. 
     An image processing device according to a second aspect of the present invention includes: filter processing means configured to perform, within a motion compensation loop of an image, filter processing for removing mosquito noise on a macroblock to be processed in the image under control according to an orthogonal transform size and syntax elements in encoding information of the macroblock; and decoding means configured to decode the image and the encoding information that have been encoded. 
     An image processing method according to the second aspect of the present invention includes the steps of: performing, with filter processing means of an image processing device, within a motion compensation loop of an image, filter processing for removing mosquito noise on a macroblock to be processed in the image under control according to an orthogonal transform size and syntax elements in encoding information of the macroblock; and decoding, with decoding means, the image and the encoding information that have been encoded. 
     With the second aspect of the present invention, within a motion compensation loop of an image, filter processing for removing mosquito noise is performed on a macroblock to be processed in the image under control according to the orthogonal transform size of the macroblock, and the encoded image and the encoded encoding information are decoded. 
     Note that the above image processing devices may be a standalone device or internal block making up one image encoding device or image decoding device. 
     Advantageous Effects of Invention 
     According to the present invention, mosquito noise can be removed. Also, according to the present invention, the image qualities of decoded images and reference images can be improved. Thus, encoding efficiency can be improved. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram illustrating a configuration example of an image encoding device employing the H.264/AVC format. 
         FIG. 2  is a block diagram illustrating a configuration example of an image decoding device employing the H.264/AVC format. 
         FIG. 3  is a block diagram illustrating a configuration example of an image encoding device to which an adaptive loop filter has been applied. 
         FIG. 4  is a block diagram illustrating a configuration example of a image decoding device to which an adaptive loop filter has been applied. 
         FIG. 5  is a block diagram illustrating the configuration of an embodiment of an image encoding device to which the present invention has been applied. 
         FIG. 6  is a diagram for describing an example of increments of orthogonal transform. 
         FIG. 7  is a diagram for describing processing in a macroblock where 4×4 orthogonal transform is performed. 
         FIG. 8  is a diagram illustrating a method for realizing integer transform and inverse integer transform by butterfly computation. 
         FIG. 9  is a diagram for describing an operating principle of a deblocking filter. 
         FIG. 10  is a diagram for describing a method of defining Bs. 
         FIG. 11  is a diagram for describing an operating principle of a deblocking filter. 
         FIG. 12  is a diagram illustrating an example of correlation between indexA and indexB, and the values of α and β. 
         FIG. 13  is a diagram illustrating an example of correlation between Bs, indexA, and tCO. 
         FIG. 14  is a diagram illustrating an example of macroblocks. 
         FIG. 15  is a block diagram illustrating a configuration example of the mosquito noise filter in  FIG. 5 . 
         FIG. 16  is a block diagram illustrating another configuration example of the mosquito noise filter in  FIG. 5 . 
         FIG. 17  is a flowchart describing encoding processing of the image encoding device in  FIG. 5 . 
         FIG. 18  is a flowchart describing intra prediction processing in step S 23  in  FIG. 17 . 
         FIG. 19  is a flowchart describing motion prediction/compensation processing in step S 24  in  FIG. 17 . 
         FIG. 20  is a flowchart describing an example of mosquito noise filter processing in step S 20  in  FIG. 17 . 
         FIG. 21  is a flowchart describing another example of mosquito noise filter processing in step S 20  in  FIG. 17 . 
         FIG. 22  is a block diagram illustrating the configuration of an embodiment of an image decoding device to which the present invention has been applied. 
         FIG. 23  is a flowchart describing decoding processing of the image decoding device in  FIG. 22 . 
         FIG. 24  is a flowchart describing the prediction processing in step S 140  in  FIG. 23 . 
         FIG. 25  is a block diagram illustrating a configuration example of the hardware of a computer. 
         FIG. 26  is a block diagram illustrating a principal configuration example of a television receiver to which the present invention has been applied. 
         FIG. 27  is a block diagram illustrating a principal configuration example of a cellular telephone to which the present invention has been applied. 
         FIG. 28  is a block diagram illustrating a principal configuration example of a hard disk recorder to which the present invention has been applied. 
         FIG. 29  is a block diagram illustrating a principal configuration example of a camera to which the present invention has been applied. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described with reference to the drawings. 
     [Configuration Example of Image Encoding Device] 
       FIG. 5  represents the configuration of an embodiment of an image encoding device serving as an image processing device to which the present invention has been applied. 
     An image encoding device  101  in  FIG. 5  is the same as the image encoding device  1  in  FIG. 1  in that there are provided the A/D conversion unit  11 , screen rearranging buffer  12 , computing unit  13 , storage buffer  17 , inverse quantization unit  18 , inverse orthogonal transform unit  19 , computing unit  20 , deblocking filter  21 , frame memory  22 , switch  23 , intra prediction unit  24 , motion prediction/compensation unit  25 , prediction image selecting unit  26 , and rate control unit  27 . 
     Also, the image encoding device  101  in  FIG. 5  differs from the imaged encoding device  1  in  FIG. 1  in that the orthogonal transform unit  14 , quantization unit  15 , and lossless encoding unit  16  are replaced with an orthogonal transform unit  111 , a quantization unit  112 , and a lossless encoding unit  113  respectively, and also in that the adaptive loop filter  71  in  FIG. 3 , and a mosquito noise filter  114  are added. 
     Specifically, the orthogonal transform unit  111  subjects, in the same way as with the orthogonal transform unit  14  in  FIG. 1 , the difference information from the computing unit  13  to orthogonal transform, such as discrete cosine transform, Karhunen-Loéve transform, or the like, and supplies a transform coefficient thereof to the quantization unit  112 . The orthogonal transform unit  111  also supplies, in contrast to the orthogonal transform unit  14  in  FIG. 1 , information relating to which of 4×4 orthogonal transform and 8×8 orthogonal transform has been applied to each macroblock (orthogonal transform size) to the mosquito noise filter  114 . 
     The quantization unit  112  quantizes, in the same way as with the quantization unit  15  in  FIG. 1 , the transform coefficient that the orthogonal transform unit  111  outputs, and supplies the quantized transform coefficient to the lossless encoding unit  113 . Also, the quantization unit  112  supplies, in contrast to the quantization unit  15  in  FIG. 1 , a quantization value relating to each macroblock to the mosquito noise filter  114 . 
     The lossless encoding unit  113  encodes, in the same way as with the lossless encoding unit  16  in  FIG. 1 , the quantized transform coefficient, and also encodes information indicating intra prediction, information indicating an inter prediction mode, and so forth to take these as part of the header information in the compressed image, and supplies the encoded data to the storage buffer  17  for storing. Note that, at this time, the lossless encoding unit  113  also encodes, such as the case in  FIG. 3 , the filter coefficient calculated by the adaptive loop filter  71  to take this as part of the header information in the compressed image. 
     Also, the lossless encoding unit  113  supplies, in contrast to the lossless encoding unit  16  in  FIG. 1 , information relating to the generated code amount of each macroblock to the mosquito noise filter  114 . 
     The mosquito noise filter  114  is provided before the adaptive loop filter  71  after the deblocking filter  21 . Specifically, the mosquito noise filter  114  is provided within a motion compensation loop made up of the computing unit  13 , orthogonal transform unit  111 , quantization unit  112 , inverse quantization unit  18 , inverse orthogonal transform unit  19 , computing unit  20 , deblocking filter  21 , adaptive loop filter  71 , frame memory  22 , switch  23 , motion prediction/compensation unit  25 , and prediction image selecting unit  26 . That is to say, an image is used by loop within the motion compensation loop. 
     The mosquito noise filter  114  uses the information from the orthogonal transform unit  111 , quantization unit  112 , and lossless encoding unit  113  to determine whether to perform filter processing for mosquito noise removal. 
     In the case of performing the filter processing, the mosquito noise filter  114  subjects a decoded image after the deblocking filter  21  to the filter processing for mosquito noise removal, and outputs the image subjected to the filter processing to the adaptive loop filter  71 . In the case of performing no filter processing, the mosquito noise filter  114  outputs the decoded image after the deblocking filter  21  to the adaptive loop filter  71  without change. [Description of Orthogonal Transform] 
     Next, each processing described above will be described in detail. First, orthogonal transform will be described with reference to  FIG. 6 . 
     With the MPEG2 encoding format, processing for orthogonal transform has been performed with 8×8 pixels as an increment. On the other hand, the image encoding device  101  which performs orthogonal transform in the same as with the AVC encoding format performs orthogonal transform with 4×4 pixels as an increment in Baseline Profile, Main Profile, and Extended Profile. Also, in High Profile or higher, the image encoding device  101  is capable of switching between orthogonal transform in increments of 4×4 pixels shown in A in  FIG. 6  and orthogonal transform in increments of 8×8 pixels shown in B in  FIG. 6 , in increments of macroblocks. [4×4 Orthogonal Transform] 
     First, the 4×4 orthogonal transform format will be described. Orthogonal transform in increments of 4×4 pixels has the following features. 
     A first feature is that with the MPEG2 encoding format, the computing precision for transform may be set freely as to each encoding format within a certain range, so there has been the necessity to implement measures for mismatch in inverse transform, but with the present method, both transform and inverse transform are stipulated in the standard, so there is no need to implement such measures for mismatch. 
     A second feature is that implementation with a 16-bit register is enabled, such that the computation is realizable with low-power-consumption type digital signal processors (DSP (Digital Signal Processor)) such as used with portable terminals or the like. 
     A third feature is that while mosquito noise due to quantization error at high-frequency coefficients has been observed with encoding methods using orthogonal transform in increments of 8×8 pixels, such as MPEG2 and the like, such mosquito noise is not readably observed with the present method. 
       FIG. 7  illustrates an overview of orthogonal transform and quantization processing. That is to say, 16×16 pixels of luminance signals and 8×8 pixels of color difference signals included in one macroblock are each divided into 4×4 pixel blocks as shown in  FIG. 7 , and each is subjected to integer transform processing and quantization processing. Further, with regard to color difference signals, as shown in  FIG. 7 , 2×2 matrices collecting only the DC component are generated, and these are subjected to Hadamard transform of the order 2 and quantization processing. 
     Also, in the event that the current macroblock is intra 16×16 mode, as shown in  FIG. 7 , 4×4 matrices collecting only the DC component are generated, and these are subjected to Hadamard transform of the order 4 and quantization. 
     Orthogonal transform processing of the order 4 can be described as in the following Expression (1). 
     
       
         
           
             
               
                 
                   [ 
                   
                     Mathematical 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     Expression 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     1 
                   
                   ] 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     
                       
                         
                           
                             [ 
                             Y 
                             ] 
                           
                           = 
                             
                           ⁢ 
                           
                             
                               
                                 
                                   [ 
                                   A 
                                   ] 
                                 
                                 ⁡ 
                                 
                                   [ 
                                   X 
                                   ] 
                                 
                               
                               ⁡ 
                               
                                 [ 
                                 A 
                                 ] 
                               
                             
                             ⊤ 
                           
                         
                       
                     
                     
                       
                         
                           = 
                             
                           ⁢ 
                           
                             
                               [ 
                               
                                 
                                   
                                     a 
                                   
                                   
                                     a 
                                   
                                   
                                     a 
                                   
                                   
                                     a 
                                   
                                 
                                 
                                   
                                     b 
                                   
                                   
                                     c 
                                   
                                   
                                     
                                       - 
                                       c 
                                     
                                   
                                   
                                     
                                       - 
                                       b 
                                     
                                   
                                 
                                 
                                   
                                     a 
                                   
                                   
                                     
                                       - 
                                       a 
                                     
                                   
                                   
                                     
                                       - 
                                       a 
                                     
                                   
                                   
                                     a 
                                   
                                 
                                 
                                   
                                     c 
                                   
                                   
                                     
                                       - 
                                       b 
                                     
                                   
                                   
                                     b 
                                   
                                   
                                     
                                       - 
                                       c 
                                     
                                   
                                 
                               
                               ] 
                             
                             ⁡ 
                             
                               [ 
                               X 
                               ] 
                             
                           
                         
                       
                     
                     
                       
                         
                             
                           ⁢ 
                           
                             [ 
                             
                               
                                 
                                   a 
                                 
                                 
                                   b 
                                 
                                 
                                   a 
                                 
                                 
                                   c 
                                 
                               
                               
                                 
                                   a 
                                 
                                 
                                   c 
                                 
                                 
                                   
                                     - 
                                     a 
                                   
                                 
                                 
                                   
                                     - 
                                     b 
                                   
                                 
                               
                               
                                 
                                   a 
                                 
                                 
                                   
                                     - 
                                     c 
                                   
                                 
                                 
                                   
                                     - 
                                     a 
                                   
                                 
                                 
                                   b 
                                 
                               
                               
                                 
                                   a 
                                 
                                 
                                   
                                     - 
                                     b 
                                   
                                 
                                 
                                   a 
                                 
                                 
                                   
                                     - 
                                     c 
                                   
                                 
                               
                             
                             ] 
                           
                         
                       
                     
                   
                   ⁢ 
                   
                     
 
                   
                   ⁢ 
                   
                     
                       
                         where 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         a 
                       
                       = 
                       
                         1 
                         2 
                       
                     
                     , 
                     
                       b 
                       = 
                       
                         
                           
                             1 
                             2 
                           
                         
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         
                           cos 
                           ⁡ 
                           
                             ( 
                             
                               π 
                               8 
                             
                             ) 
                           
                         
                       
                     
                     , 
                     
                       c 
                       = 
                       
                         
                           
                             1 
                             2 
                           
                         
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         
                           cos 
                           ⁡ 
                           
                             ( 
                             
                               
                                 3 
                                 ⁢ 
                                 π 
                               
                               8 
                             
                             ) 
                           
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
     
     The following Expression (2) is a variant which can be made of this Expression (1). 
     
       
         
           
             
               
                 
                   [ 
                   
                     Mathematical 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     Expression 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     2 
                   
                   ] 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     
                       
                         
                           
                             [ 
                             Y 
                             ] 
                           
                           = 
                             
                           ⁢ 
                           
                             
                               ( 
                               
                                 
                                   
                                     
                                       [ 
                                       C 
                                       ] 
                                     
                                     ⁡ 
                                     
                                       [ 
                                       X 
                                       ] 
                                     
                                   
                                   ⁡ 
                                   
                                     [ 
                                     C 
                                     ] 
                                   
                                 
                                 ⊤ 
                               
                               ) 
                             
                             ⊗ 
                             
                               [ 
                               E 
                               ] 
                             
                           
                         
                       
                     
                     
                       
                         
                           = 
                             
                           ⁢ 
                           
                             
                               ( 
                               
                                 
                                   
                                     [ 
                                     
                                       
                                         
                                           1 
                                         
                                         
                                           1 
                                         
                                         
                                           1 
                                         
                                         
                                           1 
                                         
                                       
                                       
                                         
                                           1 
                                         
                                         
                                           d 
                                         
                                         
                                           
                                             - 
                                             d 
                                           
                                         
                                         
                                           
                                             - 
                                             1 
                                           
                                         
                                       
                                       
                                         
                                           1 
                                         
                                         
                                           
                                             - 
                                             1 
                                           
                                         
                                         
                                           
                                             - 
                                             1 
                                           
                                         
                                         
                                           1 
                                         
                                       
                                       
                                         
                                           d 
                                         
                                         
                                           
                                             - 
                                             1 
                                           
                                         
                                         
                                           1 
                                         
                                         
                                           
                                             - 
                                             d 
                                           
                                         
                                       
                                     
                                     ] 
                                   
                                   ⁡ 
                                   
                                     [ 
                                     X 
                                     ] 
                                   
                                 
                                 ⁡ 
                                 
                                   [ 
                                   
                                     
                                       
                                         1 
                                       
                                       
                                         1 
                                       
                                       
                                         1 
                                       
                                       
                                         d 
                                       
                                     
                                     
                                       
                                         1 
                                       
                                       
                                         d 
                                       
                                       
                                         
                                           - 
                                           1 
                                         
                                       
                                       
                                         
                                           - 
                                           1 
                                         
                                       
                                     
                                     
                                       
                                         1 
                                       
                                       
                                         
                                           - 
                                           d 
                                         
                                       
                                       
                                         
                                           - 
                                           1 
                                         
                                       
                                       
                                         1 
                                       
                                     
                                     
                                       
                                         1 
                                       
                                       
                                         
                                           - 
                                           1 
                                         
                                       
                                       
                                         1 
                                       
                                       
                                         
                                           - 
                                           d 
                                         
                                       
                                     
                                   
                                   ] 
                                 
                               
                               ) 
                             
                             ⊗ 
                           
                         
                       
                     
                     
                       
                         
                             
                           ⁢ 
                           
                             [ 
                             
                               
                                 
                                   
                                     a 
                                     2 
                                   
                                 
                                 
                                   ab 
                                 
                                 
                                   
                                     a 
                                     2 
                                   
                                 
                                 
                                   ab 
                                 
                               
                               
                                 
                                   ab 
                                 
                                 
                                   
                                     b 
                                     2 
                                   
                                 
                                 
                                   ab 
                                 
                                 
                                   
                                     b 
                                     2 
                                   
                                 
                               
                               
                                 
                                   
                                     a 
                                     2 
                                   
                                 
                                 
                                   ab 
                                 
                                 
                                   
                                     a 
                                     2 
                                   
                                 
                                 
                                   ab 
                                 
                               
                               
                                 
                                   ab 
                                 
                                 
                                   
                                     b 
                                     2 
                                   
                                 
                                 
                                   ab 
                                 
                                 
                                   
                                     b 
                                     2 
                                   
                                 
                               
                             
                             ] 
                           
                         
                       
                     
                   
                   ⁢ 
                   
                     
 
                   
                   ⁢ 
                   
                     
                       
                         where 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         a 
                       
                       = 
                       
                         1 
                         2 
                       
                     
                     , 
                     
                       b 
                       = 
                       
                         
                           2 
                           5 
                         
                       
                     
                     , 
                     
                       d 
                       = 
                       
                         1 
                         2 
                       
                     
                   
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
           
         
       
     
     The following Expression (3) is a further variant which can be made of this Expression (2). 
     
       
         
           
             
               
                 
                   [ 
                   
                     Mathematical 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     Expression 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     3 
                   
                   ] 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     
                       
                         
                           [ 
                           Y 
                           ] 
                         
                         = 
                           
                         ⁢ 
                         
                           
                             ( 
                             
                               
                                 
                                   
                                     [ 
                                     
                                       C 
                                       f 
                                     
                                     ] 
                                   
                                   ⁡ 
                                   
                                     [ 
                                     X 
                                     ] 
                                   
                                 
                                 ⁡ 
                                 
                                   [ 
                                   
                                     C 
                                     f 
                                   
                                   ] 
                                 
                               
                               ⊤ 
                             
                             ) 
                           
                           ⊗ 
                           
                             [ 
                             
                               E 
                               f 
                             
                             ] 
                           
                         
                       
                     
                   
                   
                     
                       
                         = 
                           
                         ⁢ 
                         
                           
                             ( 
                             
                               
                                 
                                   [ 
                                   
                                     
                                       
                                         1 
                                       
                                       
                                         1 
                                       
                                       
                                         1 
                                       
                                       
                                         1 
                                       
                                     
                                     
                                       
                                         2 
                                       
                                       
                                         1 
                                       
                                       
                                         
                                           - 
                                           1 
                                         
                                       
                                       
                                         
                                           - 
                                           2 
                                         
                                       
                                     
                                     
                                       
                                         1 
                                       
                                       
                                         
                                           - 
                                           1 
                                         
                                       
                                       
                                         
                                           - 
                                           1 
                                         
                                       
                                       
                                         1 
                                       
                                     
                                     
                                       
                                         1 
                                       
                                       
                                         
                                           - 
                                           2 
                                         
                                       
                                       
                                         2 
                                       
                                       
                                         
                                           - 
                                           1 
                                         
                                       
                                     
                                   
                                   ] 
                                 
                                 ⁡ 
                                 
                                   [ 
                                   X 
                                   ] 
                                 
                               
                               ⁡ 
                               
                                 [ 
                                 
                                   
                                     
                                       1 
                                     
                                     
                                       2 
                                     
                                     
                                       1 
                                     
                                     
                                       1 
                                     
                                   
                                   
                                     
                                       1 
                                     
                                     
                                       1 
                                     
                                     
                                       
                                         - 
                                         1 
                                       
                                     
                                     
                                       
                                         - 
                                         2 
                                       
                                     
                                   
                                   
                                     
                                       1 
                                     
                                     
                                       
                                         - 
                                         1 
                                       
                                     
                                     
                                       
                                         - 
                                         1 
                                       
                                     
                                     
                                       2 
                                     
                                   
                                   
                                     
                                       1 
                                     
                                     
                                       
                                         - 
                                         2 
                                       
                                     
                                     
                                       1 
                                     
                                     
                                       
                                         - 
                                         1 
                                       
                                     
                                   
                                 
                                 ] 
                               
                             
                             ) 
                           
                           ⊗ 
                         
                       
                     
                   
                   
                     
                       
                           
                         ⁢ 
                         
                           [ 
                           
                             
                               
                                 
                                   a 
                                   2 
                                 
                               
                               
                                 
                                   ab 
                                   ⁢ 
                                   
                                     / 
                                   
                                   ⁢ 
                                   2 
                                 
                               
                               
                                 
                                   a 
                                   2 
                                 
                               
                               
                                 
                                   ab 
                                   ⁢ 
                                   
                                     / 
                                   
                                   ⁢ 
                                   2 
                                 
                               
                             
                             
                               
                                 ab 
                               
                               
                                 
                                   
                                     b 
                                     2 
                                   
                                   ⁢ 
                                   
                                     / 
                                   
                                   ⁢ 
                                   4 
                                 
                               
                               
                                 ab 
                               
                               
                                 
                                   
                                     b 
                                     2 
                                   
                                   ⁢ 
                                   
                                     / 
                                   
                                   ⁢ 
                                   4 
                                 
                               
                             
                             
                               
                                 
                                   a 
                                   2 
                                 
                               
                               
                                 
                                   ab 
                                   ⁢ 
                                   
                                     / 
                                   
                                   ⁢ 
                                   2 
                                 
                               
                               
                                 
                                   a 
                                   2 
                                 
                               
                               
                                 
                                   ab 
                                   ⁢ 
                                   
                                     / 
                                   
                                   ⁢ 
                                   2 
                                 
                               
                             
                             
                               
                                 
                                   ab 
                                   ⁢ 
                                   
                                     / 
                                   
                                   ⁢ 
                                   2 
                                 
                               
                               
                                 
                                   
                                     b 
                                     2 
                                   
                                   ⁢ 
                                   
                                     / 
                                   
                                   ⁢ 
                                   4 
                                 
                               
                               
                                 
                                   ab 
                                   ⁢ 
                                   
                                     / 
                                   
                                   ⁢ 
                                   2 
                                 
                               
                               
                                 
                                   
                                     b 
                                     2 
                                   
                                   ⁢ 
                                   
                                     / 
                                   
                                   ⁢ 
                                   4 
                                 
                               
                             
                           
                           ] 
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   3 
                   ) 
                 
               
             
           
         
       
     
     Accordingly, matrix [C f ] can be expressed as the following Expression (4). 
     
       
         
           
             
               
                 
                   [ 
                   
                     Mathematical 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     Expression 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     4 
                   
                   ] 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     [ 
                     
                       C 
                       f 
                     
                     ] 
                   
                   = 
                   
                     [ 
                     
                       
                         
                           1 
                         
                         
                           1 
                         
                         
                           1 
                         
                         
                           1 
                         
                       
                       
                         
                           2 
                         
                         
                           1 
                         
                         
                           
                             - 
                             1 
                           
                         
                         
                           
                             - 
                             2 
                           
                         
                       
                       
                         
                           1 
                         
                         
                           
                             - 
                             1 
                           
                         
                         
                           
                             - 
                             1 
                           
                         
                         
                           1 
                         
                       
                       
                         
                           1 
                         
                         
                           
                             - 
                             2 
                           
                         
                         
                           2 
                         
                         
                           
                             - 
                             1 
                           
                         
                       
                     
                     ] 
                   
                 
               
               
                 
                   ( 
                   4 
                   ) 
                 
               
             
           
         
       
     
     That is to say, the image encoding device  101  uses the matrix shown to the right-hand side in Expression (4) as an integer transform matrix. 
     Accordingly, integer transform can be realized by add (add-subtract) and shift (bit-shift). 
     Also, from Expression (3), matrix [E f ] can be expressed as the following Expression (5). 
     
       
         
           
             
               
                 
                   [ 
                   
                     Mathematical 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     Expression 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     5 
                   
                   ] 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     [ 
                     
                       E 
                       f 
                     
                     ] 
                   
                   = 
                   
                     [ 
                     
                       
                         
                           
                             a 
                             2 
                           
                         
                         
                           
                             ab 
                             ⁢ 
                             
                               / 
                             
                             ⁢ 
                             2 
                           
                         
                         
                           
                             a 
                             2 
                           
                         
                         
                           
                             ab 
                             ⁢ 
                             
                               / 
                             
                             ⁢ 
                             2 
                           
                         
                       
                       
                         
                           ab 
                         
                         
                           
                             
                               b 
                               2 
                             
                             ⁢ 
                             
                               / 
                             
                             ⁢ 
                             4 
                           
                         
                         
                           ab 
                         
                         
                           
                             
                               b 
                               2 
                             
                             ⁢ 
                             
                               / 
                             
                             ⁢ 
                             4 
                           
                         
                       
                       
                         
                           
                             a 
                             2 
                           
                         
                         
                           
                             ab 
                             ⁢ 
                             
                               / 
                             
                             ⁢ 
                             2 
                           
                         
                         
                           
                             a 
                             2 
                           
                         
                         
                           
                             ab 
                             ⁢ 
                             
                               / 
                             
                             ⁢ 
                             2 
                           
                         
                       
                       
                         
                           
                             ab 
                             ⁢ 
                             
                               / 
                             
                             ⁢ 
                             2 
                           
                         
                         
                           
                             
                               b 
                               2 
                             
                             ⁢ 
                             
                               / 
                             
                             ⁢ 
                             4 
                           
                         
                         
                           
                             ab 
                             ⁢ 
                             
                               / 
                             
                             ⁢ 
                             2 
                           
                         
                         
                           
                             
                               b 
                               2 
                             
                             ⁢ 
                             
                               / 
                             
                             ⁢ 
                             4 
                           
                         
                       
                     
                     ] 
                   
                 
               
               
                 
                   ( 
                   5 
                   ) 
                 
               
             
           
         
       
     
     The term at the right-hand side of this Expression (5) is realized by the image encoding device  101  performing different quantization processing for each 4×4 component. In other words, the image encoding device  101  realizes orthogonal transform by combination of integer transform and quantization processing. 
     Also, inverse integer transform can be expressed as in the following Expression (6). 
     
       
         
           
             
               
                 
                   [ 
                   
                     Mathematical 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     Expression 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     6 
                   
                   ] 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     
                       
                         
                           [ 
                           
                             X 
                             ′ 
                           
                           ] 
                         
                         = 
                           
                         ⁢ 
                         
                           
                             
                               [ 
                               
                                 C 
                                 i 
                               
                               ] 
                             
                             ⊤ 
                           
                           ⁢ 
                           
                             
                               ( 
                               
                                 
                                   [ 
                                   Y 
                                   ] 
                                 
                                 ⊗ 
                                 
                                   [ 
                                   
                                     E 
                                     i 
                                   
                                   ] 
                                 
                               
                               ) 
                             
                             ⁡ 
                             
                               [ 
                               
                                 C 
                                 i 
                               
                               ] 
                             
                           
                         
                       
                     
                   
                   
                     
                       
                         = 
                           
                         ⁢ 
                         
                           
                             [ 
                             
                               
                                 
                                   1 
                                 
                                 
                                   1 
                                 
                                 
                                   1 
                                 
                                 
                                   
                                     1 
                                     ⁢ 
                                     
                                       / 
                                     
                                     ⁢ 
                                     2 
                                   
                                 
                               
                               
                                 
                                   1 
                                 
                                 
                                   
                                     1 
                                     ⁢ 
                                     
                                       / 
                                     
                                     ⁢ 
                                     2 
                                   
                                 
                                 
                                   
                                     - 
                                     1 
                                   
                                 
                                 
                                   
                                     - 
                                     1 
                                   
                                 
                               
                               
                                 
                                   1 
                                 
                                 
                                   
                                     
                                       - 
                                       1 
                                     
                                     ⁢ 
                                     
                                       / 
                                     
                                     ⁢ 
                                     2 
                                   
                                 
                                 
                                   
                                     - 
                                     1 
                                   
                                 
                                 
                                   1 
                                 
                               
                               
                                 
                                   1 
                                 
                                 
                                   
                                     - 
                                     1 
                                   
                                 
                                 
                                   1 
                                 
                                 
                                   
                                     
                                       - 
                                       1 
                                     
                                     ⁢ 
                                     
                                       / 
                                     
                                     ⁢ 
                                     2 
                                   
                                 
                               
                             
                             ] 
                           
                           ⁢ 
                           
                             ( 
                             
                               
                                 [ 
                                 Y 
                                 ] 
                               
                               ⊗ 
                               
                                 [ 
                                 
                                   
                                     
                                       
                                         a 
                                         2 
                                       
                                     
                                     
                                       ab 
                                     
                                     
                                       
                                         a 
                                         2 
                                       
                                     
                                     
                                       ab 
                                     
                                   
                                   
                                     
                                       ab 
                                     
                                     
                                       
                                         b 
                                         2 
                                       
                                     
                                     
                                       ab 
                                     
                                     
                                       
                                         b 
                                         2 
                                       
                                     
                                   
                                   
                                     
                                       
                                         a 
                                         2 
                                       
                                     
                                     
                                       ab 
                                     
                                     
                                       
                                         a 
                                         2 
                                       
                                     
                                     
                                       ab 
                                     
                                   
                                   
                                     
                                       ab 
                                     
                                     
                                       
                                         b 
                                         2 
                                       
                                     
                                     
                                       ab 
                                     
                                     
                                       
                                         b 
                                         2 
                                       
                                     
                                   
                                 
                                 ] 
                               
                             
                             ) 
                           
                         
                       
                     
                   
                   
                     
                       
                           
                         ⁢ 
                         
                           [ 
                           
                             
                               
                                 1 
                               
                               
                                 1 
                               
                               
                                 1 
                               
                               
                                 1 
                               
                             
                             
                               
                                 1 
                               
                               
                                 
                                   1 
                                   ⁢ 
                                   
                                     / 
                                   
                                   ⁢ 
                                   2 
                                 
                               
                               
                                 
                                   
                                     - 
                                     1 
                                   
                                   ⁢ 
                                   
                                     / 
                                   
                                   ⁢ 
                                   2 
                                 
                               
                               
                                 
                                   - 
                                   1 
                                 
                               
                             
                             
                               
                                 1 
                               
                               
                                 
                                   - 
                                   1 
                                 
                               
                               
                                 
                                   - 
                                   1 
                                 
                               
                               
                                 1 
                               
                             
                             
                               
                                 
                                   1 
                                   ⁢ 
                                   
                                     / 
                                   
                                   ⁢ 
                                   2 
                                 
                               
                               
                                 
                                   - 
                                   1 
                                 
                               
                               
                                 1 
                               
                               
                                 
                                   
                                     - 
                                     1 
                                   
                                   ⁢ 
                                   
                                     / 
                                   
                                   ⁢ 
                                   2 
                                 
                               
                             
                           
                           ] 
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   6 
                   ) 
                 
               
             
           
         
       
     
     Accordingly, the right-hand side of Expression (6) can be expressed as in the following Expression (7) and Expression (8). 
     
       
         
           
             
               
                 
                   [ 
                   
                     Mathematical 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     Expression 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     7 
                   
                   ] 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     ( 
                     
                       
                         [ 
                         Y 
                         ] 
                       
                       ⊗ 
                       
                         [ 
                         
                           E 
                           i 
                         
                         ] 
                       
                     
                     ) 
                   
                   = 
                   
                     ( 
                     
                       
                         [ 
                         Y 
                         ] 
                       
                       ⊗ 
                       
                         [ 
                         
                           
                             
                               
                                 a 
                                 2 
                               
                             
                             
                               ab 
                             
                             
                               
                                 a 
                                 2 
                               
                             
                             
                               ab 
                             
                           
                           
                             
                               ab 
                             
                             
                               
                                 b 
                                 2 
                               
                             
                             
                               ab 
                             
                             
                               
                                 b 
                                 2 
                               
                             
                           
                           
                             
                               
                                 a 
                                 2 
                               
                             
                             
                               ab 
                             
                             
                               
                                 a 
                                 2 
                               
                             
                             
                               ab 
                             
                           
                           
                             
                               ab 
                             
                             
                               
                                 b 
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     The matrix shown to the right-hand side in Expression (7) is a 4×4 matrix obtained as the result of inverse quantization, while a 4×4 matrix as to the decoded image is calculated by applying the inverse integer matrix shown to the right-hand side in Expression (8). 
     Inverse integer transform also can be realized by add (add-subtract) and shift (bit-shift) alone. 
     A in  FIG. 8  and B in  FIG. 8  illustrate a technique for realizing integer transform and inverse integer transform by butterfly computation. 
     [8×8 Orthogonal Transform] 
     Next, description will be made regarding 8×8 orthogonal transform which can be used with AVC High Profile and higher. 
     With the image encoding device  101 , 8×8-orthogonal transform is defined as integer transform realized with only add-subtract and shift computation, the same as with the case of 4×4. 
     First, the image encoding device  101  performs calculation of orthogonal transform for eight points in the horizontal direction, and next performs transform for eight points in the vertical direction. 
     To simplify description, one-dimensional integer transform of order 8 will be described. 
     With input signals of {d0, d1, d2, d3, d4, d5, d6, d7}, first, calculation of the following Expression (9) through Expression (16) is performed.
 
 e 0= d 0+ d 7  (9)
 
 e 1= d 1+ d 6  (10)
 
 e 2= d 2+ d 5  (11)
 
 e 3= d 3+ d 6  (12)
 
 e 4= d 0− d 7  (13)
 
 e 5= d 1− d 6  (14)
 
 e 6= d 2− d 5  (15)
 
 e 7= d 3− d 4  (16)
 
     Next, calculation of the following Expression (17) through Expression (24) is performed for {e0, e1, e2, e3, e4, e5, e6, e7}.
 
 e′ 0= e 0+ e 3  (17)
 
 e′ 1 =e 1+ e 2  (18)
 
 e′ 2= e 0 −e 3  (19)
 
 e′ 3= e 1 −e 2  (20)
 
 e′ 4= e 5+ e 6+( e 4&gt;&gt;1+ e 4)  (21)
 
 e′ 5= e 4 −e 7−( e 6&gt;&gt;1+ e 6)  (22)
 
 e′ 6= e 4+ e 7−( e 5&gt;&gt;1+ e 5)  (23)
 
 e′ 7= e 5 −e 6+( e 7&gt;&gt;1+ e 7)  (24)
 
     Further, calculation of the following Expression (25) through Expression (32) is performed for {e′0, e′1, e′2, e′3, e′4, e′5, e′6, e′7}, obtaining orthogonally transformed coefficients {D0, D1, D2, D3, D4, D5, D6, D7}.
 
 D 0= e′ 0+ e′ 1  (25)
 
 D 2= e′ 2+ e′ 3&gt;&gt;1  (26)
 
 D 4= e′ 0 −e′ 1  (27)
 
 D 6= e′ 2&gt;&gt;1 −e′ 3  (28)
 
 D 1= e′ 4+ e′ 7&gt;&gt;2  (29)
 
 D 3= e′ 5+ e′ 6&gt;&gt;2  (30)
 
 D 5= e′ 6 −e′ 5&gt;&gt;2  (31)
 
 D 7 =−e′ 7+ e′ 4&gt;&gt;2  (32)
 
     Inverse orthogonal transform from {D0, D1, D2, D3, D4, D5, D6, D7} to {d0, d1, d2, d3, d4, d5, d6, d7} is performed as follows. 
     That is to say, first, from {D0, D1, D2, D3, D4, D5, D6, D7} to {f0, f1, f2, f3, f4, f5, f6, f7} is calculated as with the following Expression (34) through Expression (40).
 
 f 0= D 0+ D 4  (33)
 
 f 1 =−D 3+ D 5−( D 7+ D 7&gt;&gt;1)  (34)
 
 f 2= D 0 −D 4  (35)
 
 f 3= D 1+ D 7−( D 3+ D 3&gt;&gt;1)  (36)
 
 f 4= D 2&gt;&gt;1 −D 6  (37)
 
 f 5 =−D 1+ D 7+( D 5+ D 5&gt;&gt;1)  (38)
 
 f 6= D 2+ D 6&gt;&gt;1  (39)
 
 f 7= D 3+ D 5+( D 1+ D 1&gt;&gt;1)  (40)
 
     Next, from {f0, f1, f2, f3, f4, f5, f6, f7} to {f′0, f′1, f′2, f′3, f′4, f&#39;S, f′6, f′7} is calculated as with the following Expression (41) through Expression (48).
 
 f′ 0= f 0+ f 6  (41)
 
 f′ 1 =f 1+ f 7&gt;&gt;2  (42)
 
 f′ 2= f 2+ f 4  (43)
 
 f′ 3= f 3+ f 5&gt;&gt;2  (44)
 
 f′ 4= f 2− f 4  (45)
 
 f′ 5 =f 3&gt;&gt;2− f 5  (46)
 
 f′ 6= f 0− f 6  (47)
 
 f′ 7= f 7− f 1&gt;&gt;2  (48)
 
     Finally, from {f′0, f′1, f′2, f′3, f′4, f&#39;S, f′6, f′7} to {d0, d1, d2, d3, d4, d5, d6, d7} is calculated as with the following Expression (49) through Expression (56).
 
 d 0 =f′ 0 +f′ 7  (49)
 
 d 1 =f′ 2 +f′ 5  (50)
 
 d 2 =f′ 4 +f′ 3  (51)
 
 d 3 =f′ 6 +f′ 1  (52)
 
 d 4 =f′ 6 −f′ 1  (53)
 
 d 5 =f′ 4 −f′ 3  (54)
 
 d 6 =f′ 2 −f′ 5  (55)
 
 d 7 =f′ 0 −f′ 7  (56)
 
[Deblocking Filter]
 
     Next, the deblocking filter will be described. The deblocking filter  21  is included in the motion compensation loop, and removes block noise in decoded images. Accordingly, propagation of block noise to the image referenced by motion compensation processing is suppressed. 
     The following three methods of (a) through (c) for deblocking filter processing can be selected by the two parameters of deblocking_filter_control_present_flag included in Picture Parameter Set RBSP (Raw Byte Sequence Payload) and disable_deblocking_filter_idc included in the slice header (Slice Header), which are included in the encoded data. 
     (a) applied to block boundaries and macroblock boundaries 
     (b) applied to just macroblock boundaries 
     (c) not applied 
     As for a quantization parameter QP, QPY is used in the case of applying the following processing to luminance signals, and QPC is used in the case of applying to color difference signals. Also, while pixel values belonging to different slices are processed as being “not available” in motion vector encoding, intra prediction, and entropy encoding (CAVLC/CABAC), with deblocking filter processing even pixel values belonging to different slices are processed as being “available” as long as they belong to the same picture. 
     In the following we will say that the pixel values before deblocking filter processing are p0 through p3 and q0 through q3, and the pixel values after deblocking filter processing are p0′ through p3′ and q0′ through q3′, as shown in  FIG. 9 . 
     First, prior to the deblocking filter processing, Bs (Boundary Strength) is defined for p and q in  FIG. 9 , as with the table shown in  FIG. 10 . 
     The (p2, p1, p0, q0, q1, q2) in  FIG. 9  is subjected to deblocking filter processing only in the event that the conditions shown in the following Expression (57) and Expression (58) hold.
 
 Bs&gt; 0  (57)
 
| p 0− q 0|&lt;α;| p 1− p 0|&lt;β;| q 1−10|&lt;β  (58)
 
     In the default state, α and β in Expression (58) have the values thereof determined in accordance with QP as shown below, but the user can adjust the intensities thereof as indicated by the arrows in the graph in  FIG. 11 , by the two parameters called slice_alpha_c0_offset_div2 and slice_beta_offset_div2 which are included in the slice header of the encoded data. 
     As shown in the table in  FIG. 12 , α is obtained from indexA. In the same way, β is obtained from indexB. These indexA and indexB are defined as with the following Expression (59) through Expression (61).
 
 qP   aν =( qP   p   +qP   q +1)&gt;&gt;1  (59)
 
index A =Clip3(0,51, qP   aν +FilterOffset A )  (60)
 
index B =Clip3(0,51, qP   aν +FilterOffset B )  (61)
 
     In Expression (60) and Expression (61), FilterOffsetA and FilterOffsetB correspond to the amount of adjustment by the user. 
     With deblocking filter processing, mutually different methods are defined for the case of Bs&lt;4 and the case of Bs=4, as will be described below. In the case of Bs&lt;4, the pixel values p′0 and q′0 after deblocking filter processing are obtained as with the following Expression (62) through Expression (64).
 
Δ=Clip3(− t   c   ,t   c (((( q 0 −p 0)&lt;&lt;2)+( p 1− q 1)+4)&gt;&gt;3))   (62)
 
 p′ 0=Clip1( p 0+Δ)  (63)
 
 q′ 0=Clip1( q 0+Δ)  (64)
 
     Now, t c  is calculated as with Expression (65) or Expression (66) below. That is to say, in the event that the value of chromaEdgeFlag is “0”, t c  is calculated as with the following Expression (65).
 
 t   c   =t   c0 +(( a   p &lt;β)?1:0)+(( a   p &lt;β)?1:0)  (65)
 
     Also, in the event that the value of chromaEdgeFlag is other than “0”, t c  is calculated as with the following Expression (66).
 
 t   c   =t   c0 +1  (66)
 
     The value of t c0  is defined as shown in the table in A in  FIG. 13  and B in  FIG. 13 , in accordance with Bs and the value of indexA. 
     Also, the values of a p  and a q  in Expression (65) are calculated as with the following Expressions (67) and (68).
 
 a   p   =|p 2− p 0|  (67)
 
 a   q   =|q 2− q 0|  (68)
 
     The pixel value p′1 following deblocking filter processing is obtained as follows. That is to say, in the event that the value of chromaEdgeFlag is “0” and also the value of a p  is equal to or smaller than β, p′1 is obtained as with the following Expression (69).
 
 p′ 1= p 1+Clip3(− t   c0   ,t   c0 ,( p 2+(( p 0+ q 0+1)&gt;&gt;1)−( p 1&lt;&lt;1))&gt;&gt;1)  (69)
 
     Also, in the event that Expression (69) does not hold, p′1 is obtained as with the following Expression (70).
 
 p′ 1= p 1  (70)
 
     The pixel value q′1 following deblocking filter processing is obtained as follows. That is to say, in the event that the value of chromaEdgeFlag is “0” and also the value of a q  is equal to or smaller than β, q′1 is obtained as with the following Expression (71).
 
 q′ 1= q 1+Clip3(− t   c0   ,t   c0 ,( q 2+(( p 0+ q 0+1)&gt;&gt;1)−( q 1&lt;&lt;1))&gt;&gt;1)  (71)
 
     Also, in the event that Expression (71) does not hold, q′1 is obtained as with the following Expression (72).
 
 q′ 1= q 1  (72)
 
     The values of p′2 and q′2 are unchanged from the values of p2 and q2 before Filtering. That is to say, p′2 is obtained as with the following Expression (73), and q′2 is obtained as with the following Expression (74).
 
 p′ 2= p 2  (73)
 
 q′ 2= q 2  (74)
 
     In the case of Bs=4, the pixel values p′I (i=0 . . . 2) following deblocking filtering are obtained as follows. In the event that the value of chromaEdgeFlag is “0” and the conditions shown in the following Expression (75) hold, p′0, p′1, and p′2 are obtained as with the following Expression (76) through Expression (78).
 
 ap &lt;β&amp;&amp;| p 0− q 0|&lt;((α&gt;&gt;2)+2)  (75)
 
 p′ 0=( p 2+2× p 1+2× p 0+2× q 0+ q 1+4)&gt;&gt;3  (76)
 
 p′ 1=( p 2+ p 1+ p 0+ q 0+2)&gt;&gt;2  (77)
 
 p′ 2=(2× p 3+3× p 2+ p 1+ p 0+ q 0+4)&gt;&gt;3  (78)
 
     Also, in the event that the conditions shown in Expression (75) do not hold, p′0, p′1, and p′2 are obtained as with the following Expressions (79) through (81).
 
 p′ 0=(2× p 1+ p 0+ q 1+2)&gt;&gt;2  (79)
 
 p′ 1= p 1  (80)
 
 p′ 2= p 2  (81)
 
     The pixel values q′i (I=0 . . . 2) following deblocking filter processing are obtained as follows. That is, in the event that the value of chromaEdgeFlag is “0” and the conditions shown in the following Expression (82) hold, q′0, q′1, and q′2 are obtained as with the following Expressions (83) through (85).
 
 aq &lt;β&amp;&amp;| p 0− q 0|&lt;((α&gt;&gt;2)+2)  (82)
 
 q′ 0=( p 1+2× p 0+2× q 0+2× q 1+ q 2+4)&gt;&gt;3  (83)
 
 q′ 1=( p 0+ q 0+ q 1+ q 2+2)&gt;&gt;2  (84)
 
 q′ 2=(2× q 3+3× q 2+ q 1+ q 0+ p 4+4)&gt;&gt;3  (85)
 
     Also, in the event that the conditions shown in Expression (82) do not hold, q′0, q′1, and q′2 are obtained as with the following Expressions (86) through (88).
 
 q′ 0=(2× q 1+ q 0+ p 1+2)&gt;&gt;2  (86)
 
 q′ 1= q 1  (87)
 
 q′ 2= q 2  (86)
 
[Example of Extended Macroblocks]
 
     Also, making the macroblock size to be 16 pixels×16 pixels is not optimal for large image frames such as UHD (Ultra High Definition; 4000 pixels×2000 pixels) which serves the object of next-generation encoding formats. With the image encoding device  101 , as illustrated in  FIG. 14 , it may be employed to make the macroblock size a size, for example, such as 32 pixels×32 pixels or 64×64 pixels. 
       FIG. 14  is a diagram illustrating an example of a block size proposed in NPL 2. With NPL 2, the macroblock size is extended to 32×32 pixels. 
     With the upper tier in  FIG. 14 , macroblocks made up of 32×32 pixels divided into blocks (partitions) of 32×32 pixels, 32×16 pixels, 16×32 pixels, and 16×16 pixels are indicated in order from the left. With the middle tier in  FIG. 14 , blocks made up of 16×16 pixels divided into blocks of 16×16 pixels, 16×8 pixels, 8×16 pixels, and 8×8 pixels are indicated in order from the left. Also, with the lower tier in  FIG. 14 , blocks made up of 8×8 pixels divided into blocks of 8×8 pixels, 8×4 pixels, 4×8 pixels, and 4×4 pixels are indicated in order from the left. 
     That is to say, with the macroblock of 32×32 pixels, processing with blocks of 32×32 pixels, 32×16 pixels, 16×32 pixels, and 16×16 pixels indicated in the upper tier in  FIG. 14  can be performed. 
     With the block of 16×16 pixels indicated on the right side in the upper tier, in the same way as with the H.264/AVC format, processing with blocks of 16×16 pixels, 16×8 pixels, 8×16 pixels, and 8×8 pixels indicated in the middle tier can be performed. 
     With the block of 8×8 pixels indicated on the right side in the middle tier, in the same way as with the H.264/AVC format, processing with blocks of 8×8 pixels, 8×4 pixels, 4×8 pixels, and 4×4 pixels indicated in the lower tier can be performed. 
     These blocks can be classified into the following three hierarchies. Specifically, the blocks of 32×32 pixels, 32×16 pixels, and 16×32 pixels indicated in the upper tier in  FIG. 14  will be referred to as a first hierarchy. The block of 16×16 pixels indicated on the right side in the upper tier, and the blocks of 16×16 pixels, 16×8 pixels, 8×16 pixels indicated in the middle tier will be referred to as a second hierarchy. The block of 8×8 pixels indicated on the right side in the middle tier, and the blocks of 8×8 pixels, 8×4 pixels, 4×8 pixels, and 4×4 pixels indicated in the lower tier will be referred to as a third hierarchy. 
     A hierarchical structure such as  FIG. 14  is employed, and accordingly, as for blocks equal to or smaller than the block of 16×16 pixels, while maintaining compatibility with the macro blocks in the current AVC, greater blocks are defined as super sets thereof. 
     [Selection of Prediction Mode] 
     Also, in order to achieve even higher encoding efficiency, selecting an appropriate prediction mode is important. For example, with the image encoding device  101 , a method for selecting two mode determining methods of a High Complexity Mode and a Low Complexity Mode can be conceived. In the case of this method, with either, cost function values relating to each prediction mode Mode are calculated, and the prediction mode which makes this the smallest is selected as the optional mode for the current block through macroblock. 
     The cost function value with the High Complexity Mode can be obtained as with the following Expression (89).
 
Cost(Mode ∈Ω)= D+λ×R   (89)
 
     In the Expression (89), Ω is the whole set of candidate modes for encoding the current block through macroblock. Also, D is difference energy between the decoded image and input image in the case of encoding with the current prediction mode Mode. Further, λ is a Lagrange multiplier given as a function of a quantization parameter. Also, R is the total code amount in the case of encoding with the current mode Mode, including orthogonal transform coefficients. 
     That is to say, in order to perform encoding with the High Complexity Mode, there is the need to perform tentative encoding processing once by all candidate modes Mode in order to calculate the above parameters D and R, requiring a greater amount of computations. 
     On the other hand, the cost function value in the Low Complexity Mode can be obtained as shown in the following Expression (90).
 
Cost(Mode ∈Ω)= D +QP2Quant(QP)×HeaderBit  (90)
 
     it is. In Expression (90), D is the difference energy between the prediction image and input image, unlike the case of the High Complexity Mode. Also, QP2Quant (QP) is given as a function of a quantization parameter QP. Further, HeaderBit is the code amount relating to information belonging to the Header not including orthogonal transform coefficients, such as motion vectors and mode. 
     That is to say, in the Low Complexity mode, prediction processing needs to be performed relating to each candidate mode Mode, but there is not need to perform all the way to a decoded image, so there is no need to perform all the way to decoding processing. Accordingly, realization with a smaller amount of computation as compared to the High Complexity Mode is enabled. 
     With High Profile, selection between 4×4 orthogonal transform and 8×8 orthogonal transform such as shown in  FIG. 6  is also performed based on one of the above-described High Complexity Mode and Low Complexity Mode. 
     [Detailed Configuration Example] 
     With the above image encoding device  101 , mosquito noise filter processing is applied to the image encoding processing. The image encoding device  101  includes a mosquito noise filter  114  within the motion prediction/compensation loop, and controls, according to the orthogonal transform size of each macroblock, filter processing as to the macro block thereof. 
     Hereafter, description will be made regarding details of the configuration of the mosquito noise filter  114 . Mosquito noise is caused due to quantization error of orthogonal transform coefficients at high-frequency components. 
     With H.264/AVC, as described above, the orthogonal transform in 4×4 pixel increments illustrated in A in  FIG. 6 , and the orthogonal transform in 8×8 pixel increments illustrated in B in  FIG. 6  can be employed by switching in increments of macroblocks in the case of equal to or greater than High Profile. Also, as described above with reference to  FIG. 14 , in the case that a size such as 32 pixels×32 pixels, or 64×64 pixels has been employed, it can further be conceived to introduce the orthogonal transform in 16×16 pixel increments. However, mosquito noise is readily caused with a macroblock to which a greater orthogonal transform size is applied. 
     Also, though in the case that texture included in the current macroblock is flat, mosquito noise is not readily caused, in the case that an edge is included in the current macroblock, mosquito noise is readily caused. 
     In this way, whether or not mosquito noise occurs as to the current macroblock depends on the texture information and orthogonal transform size of the current macroblock. 
     With the mosquito noise filter  114  in  FIG. 5 , control is performed by taking advantage of such a fact whether to perform or not to perform filter processing for mosquito noise removal. As for this filter processing control, there are two methods. Even with either method, at least the information of an orthogonal transform size is employed. 
     First, the first method will be described. With the first method, first, activity X serving as one of Complexity (difficulty level parameters) as to the current macroblock is calculated such as the following Expression (91) using a quantization scale Q and a generation bit B in the current macroblock.
 
 X=Q*B   (91)
 
     Note that, in the case that the lossless encoding format is the CABAC format, the generation bin of the current macroblock may be employed instead of the generation bit. 
     When this activity value is high, an edge is included in the current macroblock, i.e., the current macroblock is conceived as a complicated texture, and when the activity value is low, the current macroblock is conceived as a flat region, i.e., as a simple texture. 
     In the event that the activity X calculated in this way, and a predetermined threshold Θ(T) are compared, when the following Expression (92) holds, the filter processing for mosquito noise removal is performed on a pixel value included in the current macroblock.
 
 X &gt;Θ( T )+Θ offset   (92)
 
     Here, T represents the orthogonal transform size of the current macroblock size. That is to say, a threshold Θ is determined according to the orthogonal transform size. Also, Θ offset  is an offset value that the user can set, whereby the intensity of the mosquito noise filter can be set. Note that the offset value may be omitted. 
     As for the threshold Θ, a smaller threshold is set as to a greater orthogonal transform size, whereby the mosquito noise filter can readily work. This is because mosquito noise readily occurs in the event that the orthogonal transform size is greater. 
     Next, the second method will be described. With the second method, first, the number of non-zero orthogonal transforms after quantization processing included in the current macroblock is counted. When this number is taken as N, and this N satisfies the following Expression (93) as to a predetermined threshold Θ(QP, T), the filter processing for mosquito noise removal is performed on the current macroblock.
 
 N &gt;Θ(QP, T )+Θ offset   (93)
 
With the Expression (93) as well, Θ offset  is an offset value that the user can set, whereby the intensity of the mosquito noise filter can be set. Note that the offset value may be omitted.
 
     Also, as for the predetermined quantization parameter QP, the threshold Θ is set such as the following Expression (94).
 
Θ( T= 4×4,QP)&gt;Θ( T= 8×8,QP)&gt;Θ( T= 16×16,QP)&gt; . . .  (94)
 
     That is to say, with regard to the same quantization parameter QP, a greater orthogonal transform size is set to a smaller threshold, and accordingly, the mosquito noise filter can readily work. This is because mosquito noise is readily caused in the event of a greater orthogonal transform size. 
     Also, with regard to a certain orthogonal transform size, in the event that two quantization parameters qp 1  and qp 2  are set so as to have a relation of qp 1 &lt;qp 2 , the threshold Θ is set such as the following Expression (95).
 
Θ( T ,qp 1 )&gt;Θ( T ,qp 2 )  (95)
 
     That is to say, in the event that encoding has been performed with a higher quantization parameter, it can be conceived that more quantization noise is included, and mosquito noise is readily caused, and accordingly, the mosquito noise filter can readily work by the threshold being set low. 
     That is to say, in the case of the second method, when the orthogonal transform size is great, or the quantization parameter is high, the threshold is set smaller, and accordingly, the mosquito noise filter can readily work. On the other hand, when the orthogonal transform size is small, or the quantization parameter is low, the threshold is set greater, and accordingly, the mosquito noise filter is prevented from readily working. 
     As described above, with the image encoding device  101  in  FIG. 5 , encoding information such as the orthogonal transform coefficient, orthogonal transform size, quantization value, generated code amount, and so forth as to each macroblock is used, and it is controlled (determined) whether to perform the filter processing for mosquito noise removal on the current macroblock. 
     The encoding information mentioned here is information of a syntax element that is encoded and added to the header of a compressed image and transmitted to the decoding side by the lossless encoding unit  113 . 
     Note that the scope of the present invention is not restricted to the above two methods. For example, another encoding information (syntax element) may be used for control of the mosquito noise filter. For example, as for a still region, mosquito noise is easily conspicuous, but as for a dynamic region, mosquito noise is not easily conspicuous, and accordingly, control of the mosquito noise filter can be performed by taking motion vector information to be searched by the motion prediction/compensation unit  25  into consideration. 
     As described above, in the event that it has been determined to perform the filter processing for mosquito noise removal on the current macroblock, all of the pixel values included in the determined macroblock are subjected to soothing processing by a two-dimensional filter having a predetermined window size with a pixel to be processed as the center as the filter processing for mosquito noise removal. Specifically, the smoothing processing is performed by a Gaussian filter having a 3×3 window size as indicated in the following Expression (96). 
     
       
         
           
             
               
                 
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     Note that, as for a filter coefficient for smoothing, for example, a variable filter coefficient such as an adaptive filter may be calculated and employed instead of a fixed filter coefficient such as the Expression (96). In this case, the calculated filter coefficient is added to the header of the compressed image and transmitted to the decoding side. 
     [Configuration Example of Mosquito Noise Filter] 
       FIG. 15  is a block diagram illustrating a configuration example of a mosquito noise filter for performing the first method. 
     With the example in  FIG. 15 , the mosquito noise filter  114  is configured of a threshold determining unit  151 , a Complexity calculating unit  152 , a filter control unit  153 , and a filter processing unit  154 . 
     Information relating to the orthogonal transform size of the current macroblock is supplied from the orthogonal transform unit  111  to the threshold determining unit  151 . The threshold determining unit  151  determines a threshold Θ(T) for the filter processing for removing mosquito noise based on the orthogonal transform size of the current macroblock. The information of the determined Θ(T) is supplied to the filter control unit  153 . 
     Information of a quantization value relating to the current macroblock is supplied from the quantization unit  112  to the Complexity calculating unit  152 . Information relating to the generated code amount (generation bit) of the current macroblock is supplied from the lossless encoding unit  113  to the Complexity calculating unit  152 . Note that, in the case of the CABAC method being employed as the lossless encoding method, a generation bin may be supplied instead of a generation bit. 
     The Complexity calculating unit  152  uses the above Expression (91) to calculate Complexity (activity in the case of Expression (91)) as to the current macroblock, and supplies the value of the calculated Complexity to the filter control unit  153 . 
     The filter control unit  153  determines whether to perform the filter processing for mosquito noise removal on the current macroblock using the threshold determination processing of the above Expression (92), and supplies control information thereof to the filter processing unit  154 . 
     Pixel values after deblocking filter processing serving as the output of the deblocking filter  21  are input to the filter processing unit  154  as well as the control information from the filter control unit  153 . The filter processing unit  154  uses, for example, the filter coefficient of the Expression (96) to perform filter processing based on the control information from the filter control unit  153 . The pixel values after the filter processing are output to the adaptive loop filter  71 . 
       FIG. 16  is a block diagram illustrating a configuration example of a mosquito noise filter for performing the second method. 
     With the example in  FIG. 16 , the mosquito noise filter  114  is configured of a threshold determining unit  161 , a non-zero coefficient number buffer  162 , a filter control unit  163 , and a filter processing unit  164 . 
     Information relating to the orthogonal transform size of the current macroblock from the orthogonal transform unit  111 , and information of a quantization value regarding the current macroblock from the quantization unit  112  are supplied to the threshold determining unit  161 . The threshold determining unit  161  determines a threshold Θ(QP, T) for the filter processing for removing mosquito noise based on the orthogonal transform size and quantization value of the current macroblock. Information of the determined threshold Θ(QP, T) is supplied to the filter control unit  163 . 
     Information of the number of orthogonal transform coefficients after quantization regarding the current macroblock (non-zero coefficients) is supplied from the quantization unit  112  to the non-zero coefficient number buffer  162  for storing. Information of the non-zero coefficient number stored in the non-zero coefficient number buffer  162  is supplied to the filter control unit  163 . 
     The filter control unit  163  determines whether to perform the filter processing for mosquito noise removal on the current macroblock from the information of the threshold Θ(QP, T) and the information of the non-zero coefficient number using the threshold determination processing of the above Expression (93), and supplies control information thereof to the filter processing unit  164 . 
     The pixel values after the deblocking filter processing serving as the output of the deblocking filter  21  are input to the filter processing unit  164  as well as the control information from the filter control unit  163 . The filter processing unit  164  uses the filter coefficient in the Expression (96) to perform the filter processing based on the control information from the filter control unit  163 , for example. The pixel values after the filter processing are output to the adaptive loop filter  71 . 
     [Description of Encoding Processing of Image Encoding Device] 
     Next, encoding processing of the image encoding device  101  in  FIG. 5  will be described with reference to the flowchart in  FIG. 17 . 
     In step S 11 , the A/D conversion unit  11  converts an input image from analog to digital. In step S 12 , the screen rearranging buffer  12  stores the image supplied from the A/D conversion unit  11 , and performs rearranging from the sequence for displaying the pictures to the sequence for encoding. 
     In step S 13 , the computing unit  13  computes difference between an image rearranged by the processing in step S 12  and the prediction image. The prediction image is supplied to the computing unit  13  from the motion prediction/compensation unit  25  in the event of performing inter prediction, and from the intra prediction unit  24  in the event of performing intra prediction, via the prediction image selecting unit  26 , respectively. 
     The difference data is smaller in the data amount as compared to the original image data. Accordingly, the data amount can be compressed as compared to the case of encoding the original image without change. 
     In step S 14 , the orthogonal transform unit  111  subjects the difference information supplied from the computing unit  13  to orthogonal transform. Specifically, orthogonal transform, such as discrete cosine transform, Karhunen-Loéve transform, or the like, is performed, and a transform coefficient is output. At this time, the orthogonal transform unit  111  supplies information of the orthogonal transform size of each macroblock to the mosquito noise filter  114 . 
     In step S 15 , the quantization unit  112  quantizes the transform coefficient. At this time, the quantization unit  112  supplies a quantization value relating to each macroblock to the mosquito noise filter  114 . At the time of this quantization, a rate is controlled such as later-described processing in step S 28 . 
     The difference information thus quantized is locally decoded as follows. Specifically, in step S 16 , the inverse quantization unit  18  subjects the transform coefficient quantized by the quantization unit  112  to inverse quantization using a property corresponding to the property of the quantization unit  112 . In step S 17 , the inverse orthogonal transform unit  19  subjects the transform coefficient subjected to inverse quantization by the inverse quantization unit  18  to inverse orthogonal transform using a property corresponding to the property of the orthogonal transform unit  111 . 
     In step S 18 , the computing unit  20  adds the prediction image input via the prediction image selecting unit  26  to the locally decoded difference information, and generates a locally decoded image (the image corresponding to the input to the computing unit  13 ). 
     In step S 19 , the deblocking filter  21  subjects the image output from the computing unit  20  to deblocking filtering. Thus, block noise is removed. The decoded image from the deblocking filter  21  is output to the mosquito noise filter  114 . 
     In step S 20 , the mosquito noise filer  114  subjects the decoded image after deblocking filtering to mosquito noise filtering. The details of this mosquito noise filtering will be described later with reference to  FIG. 20  and  FIG. 21 . The image from the mosquito noise filter  114  is output to the adaptive loop filter  71 . 
     In step S 21 , the adaptive loop filter  71  performs adaptive loop filtering. Specifically, the adaptive loop filter  71  performs calculation of an adaptive loop filter coefficient so as to minimize residual error between the original image from the screen rearranging buffer  12  and the image from the mosquito noise filter  114 . 
     The adaptive loop filter  71  then uses this adaptive loop filter coefficient to perform filter processing on the decoded image from the mosquito noise filter  114 . The decoded image after filter processing is output to the frame memory  22 . 
     At this time, the adaptive loop filter  71  transmits the calculated adaptive loop filter coefficient to the lossless encoding unit  113 . Information of the adaptive loop filter coefficient is encoded by the lossless encoding unit  113  in later-described step S 26 , and added to the header of the compressed image. 
     In step S 22 , the frame memory  22  stores the image subjected to filtering. Note that an image not subjected to filter processing by the deblocking filter  21  is also supplied from the computing unit  20  to the frame memory  22  for storing. 
     In the event that the image to be processed supplied from the screen rearranging buffer  12  is an image of a block to be subjected to intra processing, a decoded image to be referenced is read out from the frame memory  22 , and supplied to the intra prediction unit  24  via the switch  23 . 
     Based on these images, in step S 23 , the intra prediction unit  24  subjects pixels of a block to be processed to intra prediction in all of the intra prediction modes serving as candidates. Note that, as for a decoded pixel to be referenced, a pixel not subjected to deblocking filtering by the deblocking filter  21  is employed. 
     Though the details of the intra prediction processing in step S 23  will be described later with reference to  FIG. 18 , according to this processing, intra prediction is performed in all of the intra prediction modes serving as candidates, and a cost function value is calculated as to all of the intra prediction modes serving as candidates. Based on the calculated cost function values, the optimal intra prediction mode is then selected, the prediction image generated by intra prediction of the optimal intra prediction mode, and the cost function value thereof are supplied to the prediction image selecting unit  26 . 
     In the event that the image to be processed supplied from the screen rearranging buffer  12  is an image to be subjected to inter processing, an image to be referenced is read out from the frame memory  22 , and supplied to the motion prediction/compensation unit  25  via the switch  23 . Based on these images, in step S 24 , the motion prediction/compensation unit  25  performs motion prediction/compensation processing. 
     The details of the motion prediction/compensation processing in step S 24  will be described later with reference to  FIG. 19 . According to this processing, motion prediction processing is performed in all of the inter prediction modes serving as candidates, a cost function value is calculated as to all of the inter prediction modes serving as candidates, and based on the calculated cost function values, the optimal inter prediction mode is determined. The prediction image generated by the optimal inter prediction mode, and the cost function value thereof are then supplied to the prediction image selecting unit  26 . 
     In step S 25 , the prediction image selecting unit  26  determines one of the optimal intra prediction mode and the optimal inter prediction mode as the optimal prediction mode based on the cost function values output from the intra prediction unit  24  and motion prediction/compensation unit  25 . The prediction image selecting unit  26  then selects the prediction image of the determined optimal prediction mode, and supplies to the computing units  13  and  20 . This prediction image is used for the above computations in steps S 13  and S 18 . 
     Note that selection information of this prediction image is supplied to the intra prediction unit  24  or motion prediction/compensation unit  25 . In the event that the prediction image of the optimal intra prediction mode has been selected, the intra prediction unit  24  supplies information indicating the optimal intra prediction mode (i.e., intra prediction mode information) to the lossless encoding unit  16 . 
     In the event that the prediction image of the optimal inter prediction mode has been selected, the motion prediction/compensation unit  25  outputs information indicating the optimal inter prediction mode, and further according to need, information according to the optimal inter prediction mode to the lossless encoding unit  113 . Examples of the information according to the optimal inter prediction mode include motion vector information and reference frame information. 
     In step S 26 , the lossless encoding unit  113  encodes the quantized transform coefficient output from the quantization unit  112 . Specifically, the difference image is subjected to lossless encoding such as variable length coding, arithmetic coding, or the like, and compressed. At this time, a generation bit of the current macroblock is supplied to the mosquito noise filter  114 . Note that, in the event of the CABAC method being employed as a lossless encoding method, a generation bin may be supplied instead of a generation bit. 
     Also, at this time, the adaptive loop filter coefficient input to the lossless encoding unit  113  in the above step S 21 , and the intra prediction mode information from the intra prediction unit  24  input to the lossless encoding unit  113  in the above step S 25  or the information according to the optimal inter prediction mode from the motion prediction/compensation unit  25 , and so forth are also encoded and added to the header information. 
     For example, the information indicating the inter prediction mode is encoded for each macroblock. The motion vector information and reference frame information are encoded for each block to be processed. The adaptive loop filter coefficient is encoded for each slice. 
     In step S 27 , the storage buffer  17  stores the difference image as a compressed image. A compressed image stored in the storage buffer  17  is read out as appropriate, and transmitted to the decoding side via the transmission path. 
     In step S 28 , the rate control unit  27  controls a quantization operation rate of the quantization unit  15  based on a compressed image stored in the storage buffer  17  so as not to cause overflow or underflow. 
     [Description of Intra Prediction Processing] 
     Next, the intra prediction processing in step S 23  in  FIG. 17  will be described with reference to the flowchart in  FIG. 18 . Note that, with the example in  FIG. 18 , description will be made regarding a case of luminance signals as an example. 
     In step S 41 , the intra prediction unit  24  performs intra prediction on the intra prediction modes of 4×4 pixels, 8×8 pixels, and 16×16 pixels. 
     As for intra prediction modes of luminance signals, there are prediction modes of nine kinds of 4×4 pixel and 8×8 pixel block increments, and four kinds of 16×16 pixel macroblock increments, and as for intra prediction modes of color difference signals, there are prediction modes of four kinds of 8×8 pixel block increments. The intra prediction modes of color difference signals can be set independently of the intra prediction modes of luminance signals. With regard to the intra prediction modes of 4×4 pixels and 8×8 pixels of luminance signals, one intra prediction mode is defined for each block of 4×4 pixel and 8×8 pixel luminance signals. With regard to the intra prediction mode of 16×16 pixels of luminance signals, and the intra prediction modes of color difference signals, one prediction mode is defined as to one macroblock. 
     Specifically, the intra prediction unit  24  subjects the pixels of a block to be processed to intra prediction with reference to a decoded image read out from the frame memory  22  and supplied via the switch  23 . This intra prediction processing is performed in each intra prediction mode, and accordingly, the prediction image in each intra prediction mode is generated. Note that, as for a decoded pixel to be referenced, a pixel not subjected to deblocking filtering by the deblocking filter  21  is employed. 
     In step S 42 , the intra prediction unit  24  calculates a cost function value as to each intra prediction mode of 4×4 pixels, 8×8 pixels, and 16×16 pixels. Here, as for a cost function for obtaining a cost function value, the cost function of the Expression (89) or Expression (90) is employed. 
     In step S 43 , the intra prediction unit  24  determines the corresponding optimal mode as to each intra prediction mode of 4×4 pixels, 8×8 pixels, and 16×16 pixels. That is to say, as described above, in the cases of the intra 4×4 prediction modes and intra 8×8 prediction modes, there are the nine kinds of prediction modes, and in the cases of the intra 16×16 prediction modes, there are the four kinds of prediction modes. Accordingly, the intra prediction unit  24  determines, based on the cost function values calculated in step S 42 , out of these, the optimal intra 4×4 prediction mode, optimal intra 8×8 prediction mode, and optimal 16×16 prediction mode. 
     In step S 44 , the intra prediction unit  24  selects, out of the optimal modes determined as to the intra prediction modes of 4×4 pixels, 8×8 pixels, and 16×16 pixels, the optimal intra prediction mode based on the cost function values calculated in step S 42 , i.e., selects, out of the optimal modes determined as to 4×4 pixels, 8×8 pixels, and 16×16 pixels, a mode of which the cost function value is the minimum as the optimal intra prediction mode. The intra prediction unit  24  then supplies the prediction image generated in the optimal intra prediction mode, and the cost function value thereof to the prediction image selecting unit  26 . 
     [Description of Motion Prediction/Compensation Processing] 
     Next, the motion prediction/compensation processing in step S 24  in  FIG. 17  will be described with reference to the flowchart in  FIG. 19 . 
     In step S 61 , the motion prediction/compensation unit  25  determines a motion vector and a reference image as to eight kinds of inter prediction modes made up of 16×16 pixels through 4×4 pixels. That is to say, a motion vector and a reference image are each determined regarding the block to be processed of each inter prediction mode. 
     In step S 62 , the motion prediction/compensation unit  25  performs motion prediction and compensation processing on a reference image regarding eight kinds of inter prediction modes made up of 16×16 pixels through 4×4 pixels based on the motion vectors determined in step S 61 . According to this motion prediction and compensation processing, the prediction image in each inter prediction mode is generated. 
     In step S 63 , the motion prediction/compensation unit  25  calculates the cost function value indicated in the above Expression (89) or Expression (90) as to the eight kinds of inter prediction modes made up of 16×16 pixels through 4×4 pixels. 
     In step S 64 , the motion prediction/compensation unit  25  compares the cost function values as to the inter prediction modes calculated in step S 63 , and determines a prediction mode that provides the minimum value as the optimal inter prediction mode. The motion prediction/compensation unit  25  then supplies the prediction image generated in the optimal inter prediction mode and the cost function value thereof to the prediction image selecting unit  26 . 
     [Description of Mosquito Noise Filter Processing] 
     Next, the mosquito noise filter processing in step S 20  in  FIG. 12  will be described with reference to the flowchart in  FIG. 20 . Note that the mosquito noise filter processing in  FIG. 20  is processing to be performed by the mosquito noise filter  114  in  FIG. 15 . 
     Information of the quantization value regarding the current macroblock is supplied from the quantization unit  112  to the Complexity calculating unit  152 . Information relating to the generated code amount (generation bit) of the current macroblock is supplied from the lossless encoding unit  113  to the Complexity calculating unit  152 . 
     In step S 81 , the Complexity calculating unit  152  receives a quantization scale Q as information of the quantization value regarding the current macroblock, and in step S 82  receives a generation bit B as information regarding the generated code amount of the current macroblock. In step S 83 , the Complexity calculating unit  152  calculates activity serving as Complexity as to the current macroblock using the above Expression (91). The value of the calculated Complexity is supplied to the filter control unit  153 . 
     Information relating to the orthogonal transform size of the current macroblock is supplied from the orthogonal transform unit  111  to the threshold determining unit  151 . In step S 84 , the threshold determining unit  151  receives the orthogonal transform size of the current macroblock, and in step S 85  determines a threshold Θ=Θ(T)+Θ offset  for the filter processing for removing mosquito noise, from the orthogonal transform size of the current macroblock. Information of the determined threshold Θ is supplied to the filter control unit  153 . 
     In step S 86 , the filter control unit  153  determines whether or not the activity X from the Complexity calculating unit  152  is greater than the threshold Θ from the threshold determining unit  151 . In step S 86 , in the event that the activity X is greater than the threshold Θ, the processing proceeds to step S 87 . 
     In step S 87 , the filter processing unit  154  performs, based on the control information from the filter control unit  153 , the filter processing for mosquito noise removal on the pixel values after the deblocking filter processing, for example, using the filter coefficient of the Expression (96), and outputs the pixel values after the filter processing to the adaptive loop filter  71 . 
     On the other hand, in the event that determination is made in step S 86  that the activity X is smaller than the threshold Θ, step S 87  is skipped. That is to say, the filter processing unit  154  does not perform the filter processing on the pixel values after the deblocking filter processing based on the control information from the filter control unit  153 , and outputs to the adaptive loop filter  71  without change. 
     Further, another example of the mosquito noise filter processing in step S 20  in  FIG. 12  will be described with reference to the flowchart in  FIG. 21 . Note that the mosquito noise filter processing in  FIG. 21  is processing to be performed by the mosquito noise filter  114  in  FIG. 16 . 
     Information of the number of orthogonal transform coefficients (non-zero coefficients) after quantization relating to the current macroblock is supplied from the quantization unit  112  to the non-zero coefficient number buffer  162 . In step S 101 , the non-zero coefficient number buffer  162  receives a number N of non-zero orthogonal transform coefficients as the information of the number of orthogonal transform coefficients (non-zero coefficients) after quantization regarding the current macroblock, and stores this. The stored information of the number of non-zero coefficients number is supplied to the filter control unit  163 . 
     The information regarding the orthogonal transform size of the current macroblock from the orthogonal transform unit  111 , and the information of the quantization value regarding the current macroblock from the quantization unit  112  are supplied to the threshold determining unit  161 . 
     In step S 102 , the threshold determining unit  161  receives a quantization parameter as the information of the quantization value regarding the current macroblock, and in step S 103  receives the orthogonal transform size of the current macroblock as the information regarding the orthogonal transform size of the current macroblock. In step S 104 , the threshold determining unit  161  determines a threshold Θ=Θ(QP, T)+Θ offset  for the filter processing for removing mosquito noise from the quantization parameter and orthogonal transform size of the current macroblock. Information of the determined threshold Θ is supplied to the filter control unit  163 . 
     In step S 105 , the filter control unit  163  determines whether or not the number N of non-zero orthogonal transform coefficients from the non-zero coefficient number buffer  162  is greater than the threshold Θ from the threshold determining unit  161 . In the event that determination is made in step S 105  that the number N of non-zero orthogonal transform coefficients is greater than the threshold Θ, the processing proceeds to step S 106 . 
     In step S 106 , the filter processing unit  164  subjects the pixel values after the deblocking filter processing to the filter processing for mosquito noise removal, for example, using the filter coefficient in the Expression (96), based on the control information from the filter control unit  163 , and outputs the pixel values after the filter processing to the adaptive loop filter  71 . 
     On the other hand, in the event that determination is made in step S 105  that the number N of non-zero orthogonal transform coefficients is smaller than the threshold Θ, step S 106  is skipped. Specifically, based on the control information from the filter control unit  163 , the filter processing unit  164  does not subject the pixel values after the deblocking filter processing to the filter processing, and outputs the pixel values after the deblocking filter processing to the adaptive loop filter  71  without change. 
     The encoded compressed image is transmitted via a predetermined transmission path, and decoded by an image decoding device. 
     [Configuration Example of Image Decoding Device] 
       FIG. 22  represents the configuration of an embodiment of an image decoding device serving as the image processing device to which the present invention has been applied. 
     An image decoding device  201  in  FIG. 22  is the same as the image decoding device  31  in  FIG. 2  in that there are the storage buffer  41 , computing unit  45 , deblocking filter  46 , screen rearranging buffer  47 , D/A conversion unit  48 , frame memory  49 , switch  50 , intra prediction unit  51 , motion compensation unit  52 , and switch  53 . 
     Also, the image decoding device  201  in  FIG. 22  differs from the image decoding device  31  in  FIG. 2  in that the lossless decoding unit  42 , inverse quantization unit  43 , and inverse orthogonal transform unit  44  are replaced with a lossless decoding unit  211 , an inverse quantization unit  212 , and an inverse orthogonal transform unit  213  respectively, and in that the adaptive loop filter  91  in  FIG. 4 , and a mosquito noise filter  214  are added. 
     Specifically, the lossless decoding unit  211  decodes, in the same way as with the lossless decoding unit  42  in  FIG. 2 , information supplied from the storage buffer  41  and encoded by the lossless encoding unit  113  in  FIG. 5  using a format corresponding to the encoding format of the lossless encoding unit  113 . At this time, though motion vector information, reference frame information, prediction mode information (information indicating an intra prediction mode or inter prediction mode), an adaptive loop filter coefficient, and so forth are also decoded, the lossless decoding unit  211  supplies information relating to the generated code amount of each block to the mosquito noise filter  114  in contrast to the lossless decoding unit  42  in  FIG. 2 . 
     The inverse quantization unit  212  subjects, in the same way as with the inverse quantization unit  43  in  FIG. 2 , the image decoded by the lossless decoding unit  211  to inverse quantization using a format corresponding to the quantization format of the quantization unit  112  in  FIG. 5 . Also, the inverse quantization unit  212  supplies quantization value relating to each macroblock to the mosquito noise filter  214 , unlike the inverse quantization unit  43  in  FIG. 2 . 
     In the same way as with the inverse orthogonal transform unit  44  in  FIG. 2 , the inverse orthogonal transform unit  213  subjects the output of the inverse quantization unit  212  to inverse orthogonal transform using a format corresponding to the orthogonal transform format of the orthogonal transform unit  111  in  FIG. 5 . Also, the inverse orthogonal transform unit  213  supplies, unlike the orthogonal transform unit  44  in  FIG. 2 , information regarding which of 4×4 orthogonal transform, and 8×8 orthogonal transform has been applied to each macroblock (orthogonal transform size) to the mosquito noise filter  214 . 
     The mosquito noise filter  214  is provided after the deblocking filter  46  before the adaptive loop filter  91 . Specifically, the mosquito noise filter  214  is provided within a motion compensation loop made up of the computing unit  45 , deblocking filter  46 , adaptive loop filter  91 , frame memory  49 , switch  50 , motion compensation unit  52 , and switch  53 . That is to say, an image is used within the motion compensation loop in a loop manner. 
     The mosquito noise filter  214  uses information from the lossless decoding unit  211 , inverse quantization unit  212 , and inverse orthogonal transform unit  213  to determine whether to perform the filter processing for mosquito noise removal. 
     In the event of performing the filter processing, the mosquito noise filter  214  subjects a decoded image after the deblocking filter  46  to the filter processing for mosquito noise removal, and outputs the image subjected to the filter processing to the adaptive loop filter  91 . In the event of performing no filter processing, the mosquito noise filter  214  outputs the decoded image after the deblocking filter  46  to the adaptive loop filter  91  without change. 
     Note that the configuration example of the mosquito noise filter  214  is the same as the configuration of the mosquito noise filter  114  of the image encoding device  101  described above with reference to  FIG. 15  or  FIG. 16  only except that the input destination of information, and the input/output destination of an image differ, and accordingly, description thereof will be omitted. 
     [Description of Decoding Processing of Image Decoding Device] 
     Next, decoding processing that the image decoding device  201  executes will be described with reference to the flowchart in  FIG. 23 . 
     In step S 131 , the storage buffer  41  stores a transmitted image. In step S 132 , the lossless decoding unit  211  decodes the compressed image supplied from the storage buffer  41 . That is to say, the I picture, P picture, and B picture encoded by the lossless encoding unit  113  in  FIG. 5  are decoded. 
     At this time, the motion vector information, reference frame information, prediction mode information (information indicating an intra prediction mode or inter prediction mode), an adaptive loop filter coefficient, and so forth are also decoded. 
     Specifically, in the event that the prediction mode information is the intra prediction mode information, the prediction mode information is supplied to the intra prediction unit  51 . In the event that the prediction mode information is the inter prediction mode information, the motion vector information and reference frame information corresponding to the prediction mode information are supplied to the motion compensation unit  52 . An adaptive loop filter coefficient is decoded for each slice, and supplied to the adaptive loop filter  91 . 
     Also, at this time, the lossless decoding unit  211  supplies information relating to the generated code amount of each macroblock to the mosquito noise filter  214 . This information is used for mosquito noise filter processing in later-described step S 137 . 
     In step S 133 , the inverse quantization unit  212  subjects the transform coefficient decoded by the lossless decoding unit  211  to inverse quantization with a property corresponding to the property of the quantization unit  112  in  FIG. 5 . At this time, the inverse quantization unit  212  supplies information of a quantization value regarding a macroblock to the mosquito noise filter  214 . This information is used for the mosquito noise filter processing in later-described step S 137 . 
     In step S 134 , the inverse orthogonal transform unit  213  subjects the transform coefficient subjected to inverse quantization by the inverse quantization unit  212  to inverse orthogonal transform with a property corresponding to the property of the orthogonal transform unit  111  in  FIG. 5 . Thus, difference information corresponding to the input of the orthogonal transform unit  111  in  FIG. 5  (output of the computing unit  13 ) is decoded. Note that, at this time, the inverse orthogonal transform unit  213  supplies information regarding the orthogonal transform size of the current macroblock to the mosquito noise filter  214 . This information is used for the mosquito noise filter processing in later-described step S 137 . 
     In step S 135 , the computing unit  45  adds a prediction image to be selected at processing in later-described step S 141 , and to be input via the switch  53  to the difference information. Thus, the original image is decoded. In step S 136 , the deblocking filter  46  subjects the image output from the computing unit  45  to deblocking filter processing. Thus, block noise is removed. 
     In step S 137 , the mosquito noise filter  214  subjects the decoded image after the deblocking filter to mosquito noise filter processing using the information supplied in the above step S 132 , step S 133 , and step S 134 . The details of this mosquito noise filer processing is the same as the mosquito noise filter processing of the above image encoding device  101  described above with reference to  FIG. 20  and  FIG. 21 , and accordingly, description thereof will be omitted. The image from the mosquito noise filter  214  is output to the adaptive loop filter  91 . 
     In step S 138 , the adaptive loop filter  91  performs adaptive loop filter processing. Specifically, the adaptive loop filter coefficient is supplied from the lossless decoding unit  211  (i.e., image encoding device  101 ) to the adaptive loop filter  91  for each slice in the above step S 132 . The adaptive loop filter  91  uses the adaptive loop filter coefficient thereof to subject the decoded image from the mosquito noise filter  114  to the filter processing. The decoded image after the filter processing is output to the frame memory  49  and screen rearranging buffer  47 . 
     In step S 139 , the frame memory  49  stores the image subjected to filtering. 
     In step S 140 , the intra prediction unit  51  or motion compensation unit  52  performs prediction image generation processing in response to the prediction mode information supplied from the lossless decoding unit  211 . 
     Specifically, in the event that the intra prediction mode information has been supplied from the lossless decoding unit  211 , the intra prediction unit  51  performs intra prediction processing of an intra prediction mode to generate an intra prediction image. In the event that the inter prediction mode information has been supplied from the lossless decoding unit  211 , the motion compensation unit  52  performs motion prediction/compensation processing of an inter prediction mode to generate an inter prediction image. 
     Though the details of the prediction processing in step S 140  will be described later with reference to  FIG. 24 , according to this processing, the prediction image generated by the intra prediction unit  51  (intra prediction image) or the prediction image generated by the motion compensation unit  52  (inter prediction image) is supplied to the switch  53 . 
     In step S 141 , the switch  53  selects a prediction image. That is to say, the prediction image generated by the intra prediction unit  51 , or the prediction image generated by the motion compensation unit  52  is supplied. Accordingly, the supplied prediction image is selected and supplied to the computing unit  45 , and as described above, in step S 135  added to the output of the inverse orthogonal transform unit  213 . 
     In step S 142 , the screen rearranging buffer  47  performs rearranging of an image after the adaptive loop filter  91 . That is to say, the order of frames rearranged for encoding by the screen rearranging buffer  12  of the image encoding device  101  is rearranged in the original display order. 
     In step S 143 , the D/A conversion unit  48  converts the image from the screen rearranging buffer  47  from digital to analog. This image is output to an unshown display, and the image is displayed thereon. 
     [Description of Prediction Processing of Image Decoding Device] 
     Next, the prediction processing in step S 140  in  FIG. 23  will be described with reference to the flowchart in  FIG. 24 . 
     The intra prediction unit  51  determines in step S 171  whether or not a block to be processed has been subjected to intra encoding. Upon the intra prediction mode information being supplied from the lossless decoding unit  211  to the intra prediction unit  51 , the intra prediction unit  51  determines in step S 171  that the block to be processed has been subjected to intra encoding, and the processing proceeds to step S 172 , 
     In step S 172 , the intra prediction unit  51  obtains the intra prediction mode information, and in step S 173  performs intra prediction to generate an inter prediction image. 
     Specifically, in the event that the image to be processed is an image to be subjected to intra processing, a necessary image is read out from the frame memory  49 , and supplied to the intra prediction unit  51  via the switch  50 . In step S 173 , the intra prediction unit  51  performs intra prediction in accordance with the intra prediction mode information obtained in step S 172  to generate a prediction image. The generated prediction image is output to the switch  53 . 
     On the other hand, in the event that determination is made in step S 171  that intra prediction has not been performed, the processing proceeds to step S 174 . 
     In the event that the image to be processed is an image to be subjected to inter prediction, the inter prediction mode information, reference frame information, and motion vector information are supplied from the lossless decoding unit  211  to the motion compensation unit  52 . 
     In step S 174 , the motion compensation unit  52  obtains the prediction mode information and so forth from the lossless decoding unit  211 . Specifically, the motion (inter) prediction mode information, reference frame information, and motion vector information are obtained. 
     In step S 175 , the motion compensation unit  52  subjects the reference image from the frame memory  49  to compensation using the motion vector information to generate an inter prediction image. The generated prediction image is supplied to the computing unit  45  via the switch  53 , and in step S 135  in  FIG. 23  added to the output of the inverse orthogonal transform unit  213 . 
     As described above, with the image encoding device  101  and image decoding device  201 , the filter processing for mosquito noise removal is performed according to encoding information such as an orthogonal transform coefficient, an orthogonal transform size, a quantization value, a code amount, and so forth as to each macroblock. 
     Now, mosquito noise is local noise similar to block noise, but removal thereof is difficult at the deblocking filter  21  unlike block noise. 
     Accordingly, the filter processing for mosquito noise removal is performed according to encoding information a macroblock, and accordingly, the image quality of a decoded image improves. Further, the filter processing for mosquito noise is performed within the motion compensation loop, and accordingly, the image quality of an image to be referenced from now on also improves with motion compensation. As a result thereof, encoding efficiency is improved. 
     Also, as for control of mosquito noise, encoding information originally calculated for being transmitted to the decoding side is employed, and accordingly, there is no need to perform control by calculating new information. 
     Note that, with the above description, though an example with orthogonal transform sizes of 4×4 pixels and 8×8 pixels has been described, the orthogonal transform size is not restricted to these sizes. The present invention is also applied to a further greater orthogonal transform size. 
     With the above description, though the H.264/AVC format is employed as an encoding format, the present invention is not restricted to this, other encoding format/decoding format based on orthogonal transform and motion compensation may be applied. 
     Note that the present invention may be applied to an image encoding device and an image decoding device used at the time of receiving image information (bit streams) compressed by orthogonal transform such as discrete cosine transform or the like and motion compensation via a network medium such as satellite broadcasting, a cable television, the Internet, a cellular phone, or the like, for example, as with MPEG, H.26x, or the like. Also, the present invention may be applied to an image encoding device and an image decoding device used at the time of processing image information on storage media such as an optical disc, a magnetic disk, and flash memory. Further, the present invention may be applied to a motion prediction compensation device included in such an image encoding device and an image decoding device and so forth. 
     The above-mentioned series of processing may be executed by hardware, or may be executed by software. In the event of executing the series of processing by software, a program making up the software thereof is installed in a computer. Here, examples of the computer include a computer built into dedicated hardware, and a general-purpose personal computer whereby various functions can be executed by various types of programs being installed thereto. 
     [Configuration Example of Personal Computer] 
       FIG. 25  is a block diagram illustrating a configuration example of the hardware of a computer which executes the above-mentioned series of processing using a program. 
     With the computer, a CPU (Central Processing Unit)  251 , ROM (Read Only Memory)  252 , and RAM (Random Access Memory)  253  are mutually connected by a bus  254 . 
     Further, an input/output interface  255  is connected to the bus  254 . An input unit  256 , an output unit  257 , a storage unit  258 , a communication unit  259 , and a drive  260  are connected to the input/output interface  255 . 
     The input unit  256  is made up of a keyboard, a mouse, a microphone, and so forth. The output unit  257  is made up of a display, a speaker, and so forth. The storage unit  258  is made up of a hard disk, nonvolatile memory, and so forth. The communication unit  259  is made up of a network interface and so forth. The drive  260  drives a removable medium  261  such as a magnetic disk, an optical disc, a magneto-optical disk, semiconductor memory, or the like. 
     With the computer thus configured, for example, the CPU  251  loads a program stored in the storage unit  258  to the RAM  253  via the input/output interface  255  and bus  254 , and executes the program, and accordingly, the above-mentioned series of processing is performed. 
     The program that the computer (CPU  251 ) executes may be provided by being recorded in the removable medium  261  serving as a package medium or the like, for example. Also, the program may be provided via a cable or wireless transmission medium such as a local area network, the Internet, or digital broadcasting. 
     With the computer, the program may be installed in the storage unit  258  via the input/output interface  255  by mounting the removable medium  261  on the drive  260 . Also, the program may be received by the communication unit  259  via a cable or wireless transmission medium, and installed in the storage unit  258 . Additionally, the program may be installed in the ROM  252  or storage unit  258  beforehand. 
     Note that the program that the computer executes may be a program wherein the processing is performed in the time sequence along the sequence described in the present Specification, or may be a program wherein the processing is performed in parallel or at necessary timing such as when call-up is performed. 
     The embodiments of the present invention are not restricted to the above-mentioned embodiment, and various modifications may be made without departing from the essence of the present invention. 
     For example, the above image encoding device  101  and image decoding device  201  may be applied to an optional electric device. Hereafter, examples thereof will be described. 
     [Configuration Example of Television Receiver] 
       FIG. 26  is a block diagram illustrating a principal configuration example of a television receiver using an image decoding device to which the present invention has been applied. 
     A television receiver  300  shown in  FIG. 26  includes a terrestrial tuner  313 , a video decoder  315 , a video signal processing circuit  318 , a graphics generating circuit  319 , a panel driving circuit  320 , and a display panel  321 . 
     The terrestrial tuner  313  receives the broadcast wave signals of a terrestrial analog broadcast via an antenna, demodulates, obtains video signals, and supplies these to the video decoder  315 . The video decoder  315  subjects the video signals supplied from the terrestrial tuner  313  to decoding processing, and supplies the obtained digital component signals to the video signal processing circuit  318 . 
     The video signal processing circuit  318  subjects the video data supplied from the video decoder  315  to predetermined processing such as noise removal or the like, and supplies the obtained video data to the graphics generating circuit  319 . 
     The graphics generating circuit  319  generates the video data of a program to be displayed on a display panel  321 , or image data due to processing based on an application to be supplied via a network, or the like, and supplies the generated video data or image data to the panel driving circuit  320 . Also, the graphics generating circuit  319  also performs processing such as supplying video data obtained by generating video data (graphics) for the user displaying a screen used for selection of an item or the like, and superimposing this on the video data of a program, to the panel driving circuit  320  as appropriate. 
     The panel driving circuit  320  drives the display panel  321  based on the data supplied from the graphics generating circuit  319  to display the video of a program, or the above-mentioned various screens on the display panel  321 . 
     The display panel  321  is made up of an LCD (Liquid Crystal Display) and so forth, and displays the video of a program or the like in accordance with the control by the panel driving circuit  320 . 
     Also, the television receiver  300  also includes an audio A/D (Analog/Digital) conversion circuit  314 , an audio signal processing circuit  322 , an echo cancellation/audio synthesizing circuit  323 , an audio amplifier circuit  324 , and a speaker  325 . 
     The terrestrial tuner  313  demodulates the received broadcast wave signal, thereby obtaining not only a video signal but also an audio signal. The terrestrial tuner  313  supplies the obtained audio signal to the audio A/D conversion circuit  314 . 
     The audio A/D conversion circuit  314  subjects the audio signal supplied from the terrestrial tuner  313  to A/D conversion processing, and supplies the obtained digital audio signal to the audio signal processing circuit  322 . 
     The audio signal processing circuit  322  subjects the audio data supplied from the audio A/D conversion circuit  314  to predetermined processing such as noise removal or the like, and supplies the obtained audio data to the echo cancellation/audio synthesizing circuit  323 . 
     The echo cancellation/audio synthesizing circuit  323  supplies the audio data supplied from the audio signal processing circuit  322  to the audio amplifier circuit  324 . 
     The audio amplifier circuit  324  subjects the audio data supplied from the echo cancellation/audio synthesizing circuit  323  to D/A conversion processing, subjects to amplifier processing to adjust to predetermined volume, and then outputs the audio from the speaker  325 . 
     Further, the television receiver  300  also includes a digital tuner  316 , and an MPEG decoder  317 . 
     The digital tuner  316  receives the broadcast wave signals of a digital broadcast (terrestrial digital broadcast, BS (Broadcasting Satellite)/CS (Communications Satellite) digital broadcast) via the antenna, demodulates to obtain MPEG-TS (Moving Picture Experts Group-Transport Stream), and supplies this to the MPEG decoder  317 . 
     The MPEG decoder  317  descrambles the scrambling given to the MPEG-TS supplied from the digital tuner  316 , and extracts a stream including the data of a program serving as a playing object (viewing object). The MPEG decoder  317  decodes an audio packet making up the extracted stream, supplies the obtained audio data to the audio signal processing circuit  322 , and also decodes a video packet making up the stream, and supplies the obtained video data to the video signal processing circuit  318 . Also, the MPEG decoder  317  supplies EPG (Electronic Program Guide) data extracted from the MPEG-TS to a CPU  332  via an unshown path. 
     The television receiver  300  uses the above-mentioned image decoding device  201  as the MPEG decoder  317  for decoding video packets in this way. Accordingly, the MPEG decoder  317  can improve, in the same way as with the case of the image decoding device  201 , the image quality of decoded images, and further improve the image quality of images to be referenced from now on with motion compensation. As a result thereof, encoding efficiency is improved. 
     The video data supplied from the MPEG decoder  317  is, in the same way as with the case of the video data supplied from the video decoder  315 , subjected to predetermined processing at the video signal processing circuit  318 . The video data subjected to predetermined processing is then superimposed on the generated video data and so forth at the graphics generating circuit  319  as appropriate, supplied to the display panel  321  via the panel driving circuit  320 , and the image thereof is displayed thereon. 
     The audio data supplied from the MPEG decoder  317  is, in the same way as with the case of the audio data supplied from the audio A/D conversion circuit  314 , subjected to predetermined processing at the audio signal processing circuit  322 , supplied to the audio amplifier circuit  324  via the echo cancellation/audio synthesizing circuit  323 , and subjected to D/A conversion processing and amplifier processing. As a result thereof, the audio adjusted in predetermined volume is output from the speaker  325 . 
     Also, the television receiver  300  also includes a microphone  326 , and an A/D conversion circuit  327 . 
     The A/D conversion circuit  327  receives the user&#39;s audio signals collected by the microphone  326  provided to the television receiver  300  serving as for audio conversation, subjects the received audio signal to A/D conversion processing, and supplies the obtained digital audio data to the echo cancellation/audio synthesizing circuit  323 . 
     In the event that the user (user A)&#39;s audio data of the television receiver  300  has been supplied from the A/D conversion circuit  327 , the echo cancellation/audio synthesizing circuit  323  performs echo cancellation with the user (user A)&#39;s audio data taken as a object, and outputs audio data obtained by synthesizing with other audio data, or the like from the speaker  325  via the audio amplifier circuit  324 . 
     Further, the television receiver  300  also includes an audio codec  328 , an internal bus  329 , SDRAM (Synchronous Dynamic Random Access Memory)  330 , flash memory  331 , a CPU  332 , a USB (Universal Serial Bus) I/F  333 , and a network I/F  334 . 
     The A/D conversion circuit  327  receives the user&#39;s audio signal collected by the microphone  326  provided to the television receiver  300  serving as for audio conversation, subjects the received audio signal to A/D conversion processing, and supplies the obtained digital audio data to the audio codec  328 . 
     The audio codec  328  converts the audio data supplied from the A/D conversion circuit  327  into the data of a predetermined format for transmission via a network, and supplies to the network I/F  334  via the internal bus  329 . 
     The network I/F  334  is connected to the network via a cable mounted on a network terminal  335 . The network I/F  334  transmits the audio data supplied from the audio codec  328  to another device connected to the network thereof, for example. Also, the network I/F  334  receives, via the network terminal  335 , the audio data transmitted from another device connected thereto via the network, and supplies this to the audio codec  328  via the internal bus  329 , for example. 
     The audio codec  328  converts the audio data supplied from the network I/F  334  into the data of a predetermined format, and supplies this to the echo cancellation/audio synthesizing circuit  323 . 
     The echo cancellation/audio synthesizing circuit  323  performs echo cancellation with the audio data supplied from the audio codec  328  taken as a object, and outputs the data of audio obtained by synthesizing the audio data and other audio data, or the like, from the speaker  325  via the audio amplifier circuit  324 . 
     The SDRAM  330  stores various types of data necessary for the CPU  332  performing processing. 
     The flash memory  331  stores a program to be executed by the CPU  332 . The program stored in the flash memory  331  is read out by the CPU  332  at predetermined timing such as when activating the television receiver  300 , or the like. EPG data obtained via a digital broadcast, data obtained from a predetermined server via the network, and so forth are also stored in the flash memory  331 . 
     For example, MPEG-TS including the content data obtained from a predetermined server via the network by the control of the CPU  332  is stored in the flash memory  331 . The flash memory  331  supplies the MPEG-TS thereof to the MPEG decoder  317  via the internal bus  329  by the control of the CPU  332 , for example. 
     The MPEG decoder  317  processes the MPEG-TS thereof in the same way as with the case of the MPEG-TS supplied from the digital tuner  316 . In this way, the television receiver  300  receives the content data made up of video, audio, and so forth via the network, decodes using the MPEG decoder  317 , whereby video thereof can be displayed, and audio thereof can be output. 
     Also, the television receiver  300  also includes a light reception unit  337  for receiving the infrared signal transmitted from a remote controller  351 . 
     The light reception unit  337  receives infrared rays from the remote controller  351 , and outputs a control code representing the content of the user&#39;s operation obtained by demodulation, to the CPU  332 . 
     The CPU  332  executes the program stored in the flash memory  331  to control the entire operation of the television receiver  300  according to the control code supplied from the light reception unit  337 , and so forth. The CPU  332 , and the units of the television receiver  300  are connected via an unshown path. 
     The USB I/F  333  performs transmission/reception of data as to an external device of the television receiver  300  which is connected via a USB cable mounted on a USB terminal  336 . The network I/F  334  connects to the network via a cable mounted on the network terminal  335 , also performs transmission/reception of data other than audio data as to various devices connected to the network. 
     The television receiver  300  can improve encoding efficiency by using the image decoding device  201  as the MPEG decoder  317 . As a result thereof, the television receiver  300  can obtain and display higher image quality decoded images from broadcast signals received via an antenna or content data obtained via a network. 
     [Configuration Example of Cellular Telephone] 
       FIG. 27  is a block diagram illustrating a principal configuration example of a cellular telephone using the image encoding device and image decoding device to which the present invention has been applied. 
     A cellular telephone  400  shown in  FIG. 27  includes a main control unit  450  configured so as to integrally control the units, a power supply circuit unit  451 , an operation input control unit  452 , an image encoder  453 , a camera I/F unit  454 , an LCD control unit  455 , an image decoder  456 , a multiplexing/separating unit  457 , a recording/playing unit  462 , a modulation/demodulation circuit unit  458 , and an audio codec  459 . These are mutually connected via a bus  460 . 
     Also, the cellular telephone  400  includes operation keys  419 , a CCD (Charge Coupled Devices) camera  416 , a liquid crystal display  418 , a storage unit  423 , a transmission/reception circuit unit  463 , an antenna  414 , a microphone (MIC)  421 , and a speaker  417 . 
     Upon a call end and power key being turned on by the user&#39;s operation, the power supply circuit unit  451  activates the cellular telephone  400  in an operational state by supplying power to the units from a battery pack. 
     The cellular telephone  400  performs various operations, such as transmission/reception of an audio signal, transmission/reception of an e-mail and image data, image shooting, data recoding, and so forth, in various modes such as a voice call mode, a data communication mode, and so forth, based on the control of the main control unit  450  made up of a CPU, ROM, RAM, and so forth. 
     For example, in the voice call mode, the cellular telephone  400  converts the audio signal collected by the microphone (mike)  421  into digital audio data by the audio codec  459 , subjects this to spectrum spread processing at the modulation/demodulation circuit unit  458 , and subjects this to digital/analog conversion processing and frequency conversion processing at the transmission/reception circuit unit  463 . The cellular telephone  400  transmits the signal for transmission obtained by the conversion processing thereof to an unshown base station via the antenna  414 . The signal for transmission (audio signal) transmitted to the base station is supplied to the cellular telephone of the other party via the public telephone network. 
     Also, for example, in the voice call mode, the cellular telephone  400  amplifies the reception signal received at the antenna  414 , at the transmission/reception circuit unit  463 , further subjects to frequency conversion processing and analog/digital conversion processing, subjects to spectrum inverse spread processing at the modulation/demodulation circuit unit  458 , and converts into an analog audio signal by the audio codec  459 . The cellular telephone  400  outputs the converted and obtained analog audio signal thereof from the speaker  417 . 
     Further, for example, in the event of transmitting an e-mail in the data communication mode, the cellular telephone  400  accepts the text data of the e-mail input by the operation of the operation keys  419  at the operation input control unit  452 . The cellular telephone  400  processes the text data thereof at the main control unit  450 , and displays on the liquid crystal display  418  via the LCD control unit  455  as an image. 
     Also, the cellular telephone  400  generates e-mail data at the main control unit  450  based on the text data accepted by the operation input control unit  452 , the user&#39;s instructions, and so forth. The cellular telephone  400  subjects the e-mail data thereof to spectrum spread processing at the modulation/demodulation circuit unit  458 , and subjects to digital/analog conversion processing and frequency conversion processing at the transmission/reception circuit unit  463 . The cellular telephone  400  transmits the signal for transmission obtained by the conversion processing thereof to an unshown base station via the antenna  414 . The signal for transmission (e-mail) transmitted to the base station is supplied to a predetermined destination via the network, mail server, and so forth. 
     Also, for example, in the event of receiving an e-mail in the data communication mode, the cellular telephone  400  receives the signal transmitted from the base station via the antenna  414  with the transmission/reception circuit unit  463 , amplifies, and further subjects to frequency conversion processing and analog/digital conversion processing. The cellular telephone  400  subjects the reception signal thereof to spectrum inverse spread processing at the modulation/demodulation circuit unit  458  to restore the original e-mail data. The cellular telephone  400  displays the restored e-mail data on the liquid crystal display  418  via the LCD control unit  455 . 
     Note that the cellular telephone  400  may record (store) the received e-mail data in the storage unit  423  via the recording/playing unit  462 . 
     This storage unit  423  is an optional rewritable recording medium. The storage unit  423  may be semiconductor memory such as RAM, built-in flash memory, or the like, may be a hard disk, or may be a removable medium such as a magnetic disk, a magneto-optical disk, an optical disc, USB memory, a memory card, or the like. It goes without saying that the storage unit  423  may be other than these. 
     Further, for example, in the event of transmitting image data in the data communication mode, the cellular telephone  400  generates image data by imaging at the CCD camera  416 . The CCD camera  416  includes a CCD serving as an optical device such as a lens, diaphragm, and so forth, and serving as a photoelectric conversion device, which images a subject, converts the intensity of received light into an electrical signal, and generates the image data of an image of the subject. The CCD camera  416  performs compression encoding of the image data at the image encoder  453  via the camera I/F unit  454 , and converts into encoded image data. 
     The cellular telephone  400  employs the above-mentioned image encoding device  101  as the image encoder  453  for performing such processing. Accordingly, in the same way as with the image encoding device  101 , the image encoder  453  can improve the image quality of decoded images, and further improve the image quality of an image to be referenced from now on with motion compensation. As a result thereof, encoding efficiency is improved. 
     Note that, at this time simultaneously, the cellular telephone  400  converts the audio collected at the microphone (mike)  421 , while shooting with the CCD camera  416 , from analog to digital at the audio codec  459 , and further encodes this. 
     The cellular telephone  400  multiplexes the encoded image data supplied from the image encoder  453 , and the digital audio data supplied from the audio codec  459  at the multiplexing/separating unit  457  using a predetermined method. The cellular telephone  400  subjects the multiplexed data obtained as a result thereof to spectrum spread processing at the modulation/demodulation circuit unit  458 , and subjects to digital/analog conversion processing and frequency conversion processing at the transmission/reception circuit unit  463 . The cellular telephone  400  transmits the signal for transmission obtained by the conversion processing thereof to an unshown base station via the antenna  414 . The signal for transmission (image data) transmitted to the base station is supplied to the other party via the network or the like. 
     Note that in the event that image data is not transmitted, the cellular telephone  400  may also display the image data generated at the CCD camera  416  on the liquid crystal display  418  via the LCD control unit  455  instead of the image encoder  453 . 
     Also, for example, in the event of receiving the data of a moving image file linked to a simple website or the like in the data communication mode, the cellular telephone  400  receives the signal transmitted from the base station at the transmission/reception circuit unit  463  via the antenna  414 , amplifies, and further subjects to frequency conversion processing and analog/digital conversion processing. The cellular telephone  400  subjects the received signal to spectrum inverse spread processing at the modulation/demodulation circuit unit  458  to restore the original multiplexed data. The cellular telephone  400  separates the multiplexed data thereof at the multiplexing/separating unit  457  into encoded image data and audio data. 
     The cellular telephone  400  decodes the encoded image data at the image decoder  456 , thereby generating playing moving image data, and displays this on the liquid crystal display  418  via the LCD control unit  455 . Thus, moving image data included in a moving image file linked to a simple website is displayed on the liquid crystal display  418 , for example. 
     The cellular telephone  400  employs the above-mentioned image decoding device  201  as the image decoder  456  for performing such processing. Accordingly, in the same way as with the image decoding device  201 , the image decoder  456  can improve the image quality of decoded images, and further improve the image quality of an image to be referenced from now on with motion compensation. As a result thereof, encoding efficiency is improved. 
     At this time, simultaneously, the cellular telephone  400  converts the digital audio data into an analog audio signal at the audio codec  459 , and outputs this from the speaker  417 . Thus, audio data included in a moving image file linked to a simple website is played, for example. 
     Note that, in the same way as with the case of e-mail, the cellular telephone  400  may record (store) the received data linked to a simple website or the like in the storage unit  423  via the recording/playing unit  462 . 
     Also, the cellular telephone  400  analyzes the imaged two-dimensional code obtained by the CCD camera  416  at the main control unit  450 , whereby information recorded in the two-dimensional code can be obtained. 
     Further, the cellular telephone  400  can communicate with an external device at the infrared communication unit  481  using infrared rays. 
     The cellular telephone  400  employs the image encoding device  101  as the image encoder  453 , whereby encoding efficiency can be improved. As a result, the cellular telephone  400  can provide encoded data (image data) with good encoding efficiency to another device. 
     Also, the cellular telephone  400  employs the image decoding device  201  as the image decoder  456 , whereby encoding efficiency can be improved. As a result thereof, the cellular telephone  400  can obtain and display higher definition decoded images from a moving image file linked to at a simple website or the like, for example. 
     Note that description has been made so far wherein the cellular telephone  400  employs the CCD camera  416 , but the cellular telephone  400  may employ an image sensor (CMOS image sensor) using CMOS (Complementary Metal Oxide Semiconductor) instead of this CCD camera  416 . In this case as well, the cellular telephone  400  can image a subject and generate the image data of an image of the subject in the same way as with the case of employing the CCD camera  416 . 
     Also, description has been made so far regarding the cellular telephone  400 , but the image encoding device  101  and the image decoding device  201  may be applied to any kind of device in the same way as with the case of the cellular telephone  400  as long as it is a device having the same imaging function and communication function as those of the cellular telephone  400 , for example, such as a PDA (Personal Digital Assistants), smart phone, UMPC (Ultra Mobile Personal Computer), net book, notebook-sized personal computer, or the like. 
     [Configuration Example of Hard Disk Recorder] 
       FIG. 28  is a block diagram illustrating a principal configuration example of a hard disk recorder which employs the image encoding device and image decoding device to which the present invention has been applied. 
     A hard disk recorder (HDD recorder)  500  shown in  FIG. 28  is a device which stores, in a built-in hard disk, audio data and video data of a broadcast program included in broadcast wave signals (television signals) received by a tuner and transmitted from a satellite or a terrestrial antenna or the like, and provides the stored data to the user at timing according to the user&#39;s instructions. 
     The hard disk recorder  500  can extract audio data and video data from broadcast wave signals, decode these as appropriate, and store in the built-in hard disk, for example. Also, the hard disk recorder  500  can also obtain audio data and video data from another device via the network, decode these as appropriate, and store in the built-in hard disk, for example. 
     Further, the hard disk recorder  500  can decode audio data and video data recorded in the built-in hard disk, supply this to a monitor  560 , display an image thereof on the screen of the monitor  560 , and output audio thereof from the speaker of the monitor  560 , for example. 
     The hard disk recorder  500  can decode audio data and video data extracted from broadcast signals obtained via a tuner, or audio data and video data obtained from another device via a network, supply this to the monitor  560 , display an image thereof on the screen of the monitor  560 , and output audio thereof from the speaker of the monitor  560 , for example. 
     Of course, operations other than these may be performed. As shown in  FIG. 28 , the hard disk recorder  500  includes a reception unit  521 , a demodulation unit  522 , a demultiplexer  523 , an audio decoder  524 , a video decoder  525 , and a recorder control unit  526 . The hard disk recorder  500  further includes EPG data memory  527 , program memory  528 , work memory  529 , a display converter  530 , an OSD (On Screen Display) control unit  531 , a display control unit  532 , a recording/playing unit  533 , a D/A converter  534 , and a communication unit  535 . 
     Also, the display converter  530  includes a video encoder  541 . The recording/playing unit  533  includes an encoder  551  and a decoder  552 . 
     The reception unit  521  receives the infrared signal from the remote controller (not shown), converts into an electrical signal, and outputs to the recorder control unit  526 . The recorder control unit  526  is configured of, for example, a microprocessor and so forth, and executes various types of processing in accordance with the program stored in the program memory  528 . At this time, the recorder control unit  526  uses the work memory  529  according to need. 
     The communication unit  535 , which is connected to the network, performs communication processing with another device via the network. For example, the communication unit  535  is controlled by the recorder control unit  526  to communicate with a tuner (not shown), and to principally output a channel selection control signal to the tuner. 
     The demodulation unit  522  demodulates the signal supplied from the tuner, and outputs to the demultiplexer  523 . The demultiplexer  523  separates the data supplied from the demodulation unit  522  into audio data, video data, and EPG data, and outputs to the audio decoder  524 , video decoder  525 , and recorder control unit  526 , respectively. 
     The audio decoder  524  decodes the input audio data, for example, with the MPEG format, and outputs to the recording/playing unit  533 . The video decoder  525  decodes the input video data, for example, with the MPEG format, and outputs to the display converter  530 . The recorder control unit  526  supplies the input EPG data to the EPG data memory  527  for storing. 
     The display converter  530  encodes the video data supplied from the video decoder  525  or recorder control unit  526  into, for example, the video data conforming to the NTSC (National Television Standards Committee) format using the video encoder  541 , and outputs to the recording/playing unit  533 . Also, the display converter  530  converts the size of the screen of the video data supplied from the video decoder  525  or recorder control unit  526  into the size corresponding to the size of the monitor  560 , converts the video data of which the screen size has been converted into the video data conforming to the NTSC format using the video encoder  541 , converts into an analog signal, and outputs to the display control unit  532 . 
     The display control unit  532  superimposes, under the control of the recorder control unit  526 , the OSD signal output from the OSD (On Screen Display) control unit  531  on the video signal input from the display converter  530 , and outputs to the display of the monitor  560  for displaying. 
     Also, the audio data output from the audio decoder  524  has been converted into an analog signal using the D/A converter  534 , and supplied to the monitor  560 . The monitor  560  outputs this audio signal from the built-in speaker. 
     The recording/playing unit  533  includes a hard disk as a recording medium in which video data, audio data, and so forth are recorded. 
     The recording/playing unit  533  encodes the audio data supplied from the audio decoder  524  with the MPEG format by the encoder  551 . Also, the recording/playing unit  533  encodes the video data supplied from the video encoder  541  of the display converter  530  with the MPEG format by the encoder  551 . The recording/playing unit  533  synthesizes the encoded data of the audio data thereof, and the encoded data of the video data thereof using the multiplexer. The recording/playing unit  533  amplifies the synthesized data thereof by channel coding, and writes the data thereof in the hard disk via a recording head. 
     The recording/playing unit  533  plays the data recorded in the hard disk via a playing head, amplifies, and separates into audio data and video data using the demultiplexer. The recording/playing unit  533  decodes the audio data and video data by the decoder  552  using the MPEG format. The recording/playing unit  533  converts the decoded audio data from digital to analog, and outputs to the speaker of the monitor  560 . Also, the recording/playing unit  533  converts the decoded video data from digital to analog, and outputs to the display of the monitor  560 . 
     The recorder control unit  526  reads out the latest EPG data from the EPG data memory  527  based on the user&#39;s instructions indicated by the infrared signal from the remote controller which is received via the reception unit  521 , and supplies to the OSD control unit  531 . The OSD control unit  531  generates image data corresponding to the input EPG data, and outputs to the display control unit  532 . The display control unit  532  outputs the video data input from the OSD control unit  531  to the display of the monitor  560  for displaying. Thus, EPG (Electronic Program Guide) is displayed on the display of the monitor  560 . 
     Also, the hard disk recorder  500  can obtain various types of data such as video data, audio data, EPG data, and so forth supplied from another device via the network such as the Internet or the like. 
     The communication unit  535  is controlled by the recorder control unit  526  to obtain encoded data such as video data, audio data, EPG data, and so forth transmitted from another device via the network, and to supply this to the recorder control unit  526 . The recorder control unit  526  supplies the encoded data of the obtained video data and audio data to the recording/playing unit  533 , and stores in the hard disk, for example. At this time, the recorder control unit  526  and recording/playing unit  533  may perform processing such as re-encoding or the like according to need. 
     Also, the recorder control unit  526  decodes the encoded data of the obtained video data and audio data, and supplies the obtained video data to the display converter  530 . The display converter  530  processes, in the same way as the video data supplied from the video decoder  525 , the video data supplied from the recorder control unit  526 , supplies to the monitor  560  via the display control unit  532  for displaying an image thereof. 
     Alternatively, an arrangement may be made wherein in accordance with this image display, the recorder control unit  526  supplies the decoded audio data to the monitor  560  via the D/A converter  534 , and outputs audio thereof from the speaker. 
     Further, the recorder control unit  526  decodes the encoded data of the obtained EPG data, and supplies the decoded EPG data to the EPG data memory  527 . 
     The hard disk recorder  500  thus configured employs the image decoding device  201  as the video decoder  525 , decoder  552 , and decoder housed in the recorder control unit  526 . Accordingly, in the same way as with the image decoding device  201 , the video decoder  525 , decoder  552 , and decoder housed in the recorder control unit  526  can improve the image quality of decoded images, and further improve the image quality of an image to be referenced from now on with motion compensation. As a result thereof, encoding efficiency is improved. 
     Accordingly, the hard disk recorder  500  can realize increase in processing speed, and also generate higher definition prediction images. As a result thereof, the hard disk recorder  500  can obtain higher definition decoded images from encoded data of video data received via the tuner, from encoded data of video data read out from the hard disk of the recording/playing unit  533 , and encoded data of video data obtained via the network, and display on the monitor  560 , for example. 
     Also, the hard disk recorder  500  employs the image encoding device  101  as the encoder  551 . Accordingly, in the same way as with the case of the image encoding device  101 , the encoder  551  can improve the image quality of decoded images, and further improve the image quality of an image to be referenced from now on with motion compensation. As a result thereof, encoding efficiency is improved. 
     Accordingly, the hard disk recorder  500  can realize increase in processing speed, and also improve encoding efficiency of encoded data to be recorded in the hard disk, for example. As a result thereof, the hard disk recorder  500  can more effectively use the storage region of the hard disk. 
     Note that description has been made so far regarding the hard disk recorder  500  for recording video data and audio data in the hard disk, but it goes without saying that any kind of recording medium may be employed. For example, even with a recorder to which a recording medium other than a hard disk, such as flash memory, optical disc, video tape, or the like, is applied, the image encoding device  101  and image decoding device  201  can be applied thereto in the same way as with the case of the above hard disk recorder  500 . [Configuration Example of Camera] 
       FIG. 29  is a block diagram illustrating a principal configuration example of a camera employing the image encoding device and image decoding device to which the present invention has been applied. 
     A camera  600  shown in  FIG. 29  images a subject, displays an image of the subject on an LCD  616 , and records this in a recording medium  633  as image data. 
     A lens block  611  inputs light (i.e., picture of a subject) to a CCD/CMOS  612 . The CCD/CMOS  612  is an image sensor employing a CCD or CMOS, which converts the intensity of received light into an electrical signal, and supplies to a camera signal processing unit  613 . 
     The camera signal processing unit  613  converts the electrical signal supplied from the CCD/CMOS  612  into color difference signals of Y, Cr, and Cb, and supplies to an image signal processing unit  614 . The image signal processing unit  614  subjects, under the control of a controller  621 , the image signal supplied from the camera signal processing unit  613  to predetermined image processing, or encodes the image signal thereof by an encoder  641  using the MPEG format for example. The image signal processing unit  614  supplies encoded data generated by encoding an image signal, to a decoder  615 . Further, the image signal processing unit  614  obtains data for display generated at an on-screen display (OSD)  620 , and supplies this to the decoder  615 . 
     With the above-mentioned processing, the camera signal processing unit  613  appropriately takes advantage of DRAM (Dynamic Random Access Memory)  618  connected via a bus  617  to hold image data, encoded data encoded from the image data thereof, and so forth in the DRAM  618  thereof according to need. 
     The decoder  615  decodes the encoded data supplied from the image signal processing unit  614 , and supplies obtained image data (decoded image data) to the LCD  616 . Also, the decoder  615  supplies the data for display supplied from the image signal processing unit  614  to the LCD  616 . The LCD  616  synthesizes the image of the decoded image data, and the image of the data for display, supplied from the decoder  615  as appropriate, and displays a synthesizing image thereof. 
     The on-screen display  620  outputs, under the control of the controller  621 , data for display such as a menu screen or icon or the like made up of a symbol, characters, or a figure to the image signal processing unit  614  via the bus  617 . 
     Based on a signal indicating the content commanded by the user using an operating unit  622 , the controller  621  executes various types of processing, and also controls the image signal processing unit  614 , DRAM  618 , external interface  619 , on-screen display  620 , media drive  623 , and so forth via the bus  617 . Programs, data, and so forth necessary for the controller  621  executing various types of processing are stored in FLASH ROM  624 . 
     For example, the controller  621  can encode image data stored in the DRAM  618 , or decode encoded data stored in the DRAM  618  instead of the image signal processing unit  614  and decoder  615 . At this time, the controller  621  may perform encoding/decoding processing using the same format as the encoding/decoding format of the image signal processing unit  614  and decoder  615 , or may perform encoding/decoding processing using a format that neither the image signal processing unit  614  nor the decoder  615  can handle. 
     Also, for example, in the event that start of image printing has been instructed from the operating unit  622 , the controller  621  reads out image data from the DRAM  618 , and supplies this to a printer  634  connected to the external interface  619  via the bus  617  for printing. 
     Further, for example, in the event that image recording has been instructed from the operating unit  622 , the controller  621  reads out encoded data from the DRAM  618 , and supplies this to a recording medium  633  mounted on the media drive  623  via the bus  617  for storing. 
     The recording medium  633  is an optional readable/writable removable medium, for example, such as a magnetic disk, a magneto-optical disk, an optical disc, semiconductor memory, or the like. It goes without saying that the recording medium  633  is also optional regarding the type of a removable medium, and accordingly may be a tape device, or may be a disc, or may be a memory card. It goes without saying that the recoding medium  633  may be a non-contact IC card or the like. 
     Alternatively, the media drive  623  and the recording medium  633  may be configured so as to be integrated into a non-transportable recording medium, for example, such as a built-in hard disk drive, SSD (Solid State Drive), or the like. 
     The external interface  619  is configured of, for example, a USB input/output terminal and so forth, and is connected to the printer  634  in the event of performing printing of an image. Also, a drive  631  is connected to the external interface  619  according to need, on which the removable medium  632  such as a magnetic disk, optical disc, or magneto-optical disk is mounted as appropriate, and a computer program read out therefrom is installed in the FLASH ROM  624  according to need. 
     Further, the external interface  619  includes a network interface to be connected to a predetermined network such as a LAN, the Internet, or the like. For example, in accordance with the instructions from the operating unit  622 , the controller  621  can read out encoded data from the DRAM  618 , and supply this from the external interface  619  to another device connected via the network. Also, the controller  621  can obtain, via the external interface  619 , encoded data or image data supplied from another device via the network, and hold this in the DRAM  618 , or supply this to the image signal processing unit  614 . 
     The camera  600  thus configured employs the image decoding device  201  as the decoder  615 . Accordingly, in the same way as with the image decoding device  201 , the decoder  615  can improve the image quality of decoded images, and further improve the image quality of an image to be referenced from now on with motion compensation. As a result thereof, encoding efficiency is improved. 
     Accordingly, the camera  600  can generate a prediction image with high precision. As a result thereof, the camera  600  can obtain higher definition decoded images at higher speed from, for example, image data generated at the CCD/CMOS  612 , encoded data of video data read out from the DRAM  618  or recording medium  633 , and encoded data of video data obtained via a network, and display on the LCD  616 . 
     Also, the camera  600  employs the image encoding device  101  as the encoder  641 . Accordingly, in the same way as with the case of the image encoding device  101 , the encoder  641  can improve the image quality of decoded images, and further improve the image quality of an image to be referenced from now on with motion compensation. As a result thereof, encoding efficiency is improved. 
     Accordingly, the camera  600  can improve encoding efficiency of encoded data to be recorded in the hard disk, for example. As a result thereof, the camera  600  can more effectively use the storage region of the DRAM  618  or recording medium  633  at higher speed. 
     Note that the decoding method of the image decoding device  201  may be applied to the decoding processing which the controller  621  performs. In the same way, the encoding method of the image encoding device  101  may be applied to the encoding processing which the controller  621  performs. 
     Also, the image data which the camera  600  takes may be moving images or may be still images. 
     As a matter of course, the image encoding device  101  and image decoding device  201  may be applied to devices or systems other than the above-described devices. 
     REFERENCE SIGNS LIST 
       101  image encoding device,  111  orthogonal transform unit,  112  quantization unit,  113  lossless encoding unit,  114  mosquito noise filter,  151  threshold determining unit,  152  Complexity calculating unit,  153  filter control unit,  154  filter processing unit,  161  threshold determining unit,  162  non-zero coefficient number buffer,  163  filter control unit,  164  filter processing unit,  201  image decoding device,  211  lossless decoding unit,  212  inverse quantization unit,  213  inverse orthogonal transform unit,  214  mosquito noise filter