Abstract:
An image processing device has an image composition component that combines a plurality of image signals to obtain a single composite image signal, and an image compression coding component that compresses and encodes the single composite image signal so as to obtain a compression coded image signal.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates generally to an image processing apparatus, an image recording apparatus and an image reproduction apparatus, and more particularly, to an improved image processing apparatus, image recording apparatus and image reproduction apparatus employing an image processing technique that compresses a plurality of image signals into a single composite image.  
           [0003]    2. Description of the Related Art  
           [0004]    A security camera recorder system that records video images from, for example, security and surveillance cameras, typically employs a method in which images from a plurality of cameras are stored in a given sequence in a memory bank, a single frame is formed from the respective images of each of the cameras, the image so formed is compressed using the so-called JPEG (Joint Photographic Experts Group) standard, and the compressed images are stored in a storage/recordation unit such as a VCR or hard disk.  
           [0005]    In order to further an understanding of the background art and hence the innovativeness of the claimed present invention, a more detailed description will now be given of a conventional security camera recording system and the conventional recording method employed therein.  
           [0006]    [0006]FIG. 1 is a block diagram of a conventional security camera recording system.  
           [0007]    As shown in the diagram, in this instance a security camera recorder  1  is connected to four different surveillance cameras  2   a,    2   b,    2   c  and  2   d  (hereinafter  2   a - 2   d ), the four surveillance cameras  2   a - 2   d  being positioned to photograph a target image from different points and angles.  
           [0008]    The images acquired by the cameras  2   a - 2   d  each form an independent single frame (one frame), with each such frame being stored, frame by frame, in the frame memory banks  3   a,    3   b,    3   c  and  3   d  (hereinafter frame memory banks  3   a - 3   d ).  
           [0009]    The images stored in the frame memory  3   a - 3   d  (that is, the image signals) are input to an A/D converter  5  while being switched by a frame switch  4 .  
           [0010]    In this instance, the input line, that is, the sequence, of the image signals read out from the frame memory banks  3   a - 3   d  is controlled by a control signal supplied from the frame switch  4  from a frame selection component  6 .  
           [0011]    Purely for purposes of illustration, assume, for example, a case in which the frame selection component  6  is set so as to record all the images from all the cameras  2   a - 2   d.  The frame switch  4  then switches the input to the A/D converter  5  (the so-called input line) so as to follow the sequence camera  2   a →camera  2   b →camera  2   c →camera  2   d,  so that image signals are read out in order from the frame memory banks  3   a   3   d.    
           [0012]    Or, in a case in which the frame selection component is set so as to record images from camera  2   a , camera  2   c  and camera  2   d , the frame switch  4  sets the input to the A/D converter (the input line) so as to follow the sequence camera  2   a →camera  2   c →camera  2   d →camera  2   a , so that image signals are read out in order from the memory  3   a - 3   d.    
           [0013]    It should be noted that by changing the settings of the controls component  7 , the control signals of the frame selection component using the control signals supplied from the controls  7  in turn controls the frame switch  4 , so the order in which the image signals are read out from the memory  3   a - 3   d  can be changed at will.  
           [0014]    The image signals input into the A/D converter  5  via the frame switch  4  are then supplied to an encoding component  8 , which compresses the images so supplied using the JPEG (Joint Photographic Experts Group) standard, after which the compressed images are stored in a storage unit  9 .  
           [0015]    When the stored images are to be read (that is played back, or, in other words, reproduced; hereinafter reproduced), the encoded image signals read out from the storage unit  9  are decoded by a decoding component  10  and stored in the frame memory unit  11 . At this point a desired frame can then be called up from the frame memory unit  11  so as to be viewed by the frame selection component  6  using the controls  7 , with the appropriate image signals being read out, converted by a D/A converter  12 A and displayed on the display monitor  13 .  
           [0016]    A disadvantage of the above-described conventional recording and reproduction method is as follows.  
           [0017]    Specifically, the above-described JPEG standard encoding component  8  employed by the security camera recorder  1  can efficiently reduce the amount of information required for still-image processing and even for moving-image processing using frame-internal predictive coding, because it converts secondary image information into the frequency band and is given an energy bias and carries out quantification and entropy encoding according to that bias.  
           [0018]    However, such a set-up is inadequate for efficiently recording moving pictures, which require the processing of relatively large amounts of information.  
           [0019]    Accordingly, a different method of compressing moving pictures known as the MPEG (Moving Pictures Expert Group) standard has been put forward, and has gradually begun to be adopted for use with security camera recorders as well.  
           [0020]    In the MPEG standard, an inter-image (that is, an inter-frame) moving vector is detected and the image compressed while being interpolated using that moving vector. As a result of such interpolation, however, the degree of correlation between frames becomes vitally important.  
           [0021]    However, because the conventional security camera recorder employs a recording method that switches among a plurality of camera images, there is little correlation between frames of differing image signals.  
           [0022]    As a result, even under the MPEG standard of compression coding for image data, it is impossible to obtain an inter-frame moving vector. Accordingly, each image signal is compressed as is, with a consequent deterioration in compression efficiency.  
         SUMMARY OF THE INVENTION  
         [0023]    Accordingly, it is an object of the present invention to provide an improved and useful improved image processing apparatus, image recording apparatus and image reproduction apparatus in which the above-described disadvantage is eliminated.  
           [0024]    The above-described objects of the present invention are achieved by an image processing apparatus having an image composition component that combines a plurality of image signals to obtain a single composite image signal and an image compression coding component that compresses and encodes the single composite image signal to obtain a compression coded image signal.  
           [0025]    According to this first aspect of the invention, the plurality of image signals are given a high degree of correlation between successive frames of the composite image signal, which is preferable for compression coding, and in particular, is more preferable for use with the MPEG standard for compression coding of image data.  
           [0026]    It is preferable that the above-described image processing apparatus also include an editing component that supplies editing control signal to the image composition component in order to edit the plurality of image signals.  
           [0027]    Additionally, it is preferable that the image composition component comprise a plurality of memory components for storing each of the plurality of image signals, an image signal switching component for selectively switching the image signals to be input into the plurality of memory components, a read control component that supplies a read control signal to the plurality of memory components so as to read out image signals stored therein, and an image processing component for processing the image signals read out from the plurality of memory components using the editing control signal from the editing component. Additionally, it is preferable that the read control component supplies a read clock signal to the plurality of memory components using the editing control signal from the editing component, the read clock signal corresponding to a multiple of the plurality of image signals needed to obtain the composite image signal.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]    These and other objects, features, aspects and advantages of the present invention will become better understood and more apparent from the following description, appended claims and accompanying drawings, in which:  
         [0029]    [0029]FIG. 1 is a block diagram of a conventional security camera;  
         [0030]    [0030]FIG. 2 is a block diagram of a security camera recorder according to one embodiment of the present invention;  
         [0031]    [0031]FIGS. 3A and 3B are diagrams illustrating a first sample composite image edited using one embodiment of the present invention, in which FIG. 3A shows the composite image formed by image signals of individual cameras and FIG. 3B shows a timing chart of same;  
         [0032]    [0032]FIGS. 4A and 4B are diagrams illustrating a second sample composite image edited by one embodiment of the present invention, in which FIG. 4A shows the composite image formed by image signals of individual cameras and FIG. 4B shows a timing chart of same;  
         [0033]    [0033]FIGS. 5A and 5B are diagrams illustrating a third sample composite image edited by one embodiment of the present invention, in which FIG. 5A shows the composite image formed by image signals of individual cameras and FIG. 5B shows a timing chart of same; and  
         [0034]    [0034]FIGS. 6A and 6B are diagrams illustrating a fourth sample composite image edited by one embodiment of the present invention, in which FIG. 6A shows the composite image formed by image signals of individual cameras and FIG. 6B shows a timing chart of same.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0035]    A detailed description will now be given of an improved optical disk recording apparatus according to the present invention, with reference to the accompanying drawings and taking a security camera recorder as an example of an application thereof for purposes of illustration only. It should be noted that identical or corresponding elements are given identical or corresponding reference numbers in all drawings, with detailed descriptions thereof given once and thereafter omitted.  
         [0036]    [0036]FIG. 2 is a block diagram of a security camera recording system according to one embodiment of the present invention.  
         [0037]    As shown in FIG. 2, a security camera recording system  10  according to one embodiment of the present invention comprises a recording component (image recording apparatus) and a reproduction component (image reproduction apparatus). Generally, the recording component comprises one or more camera units  12 , an image composition apparatus  14 , an encoding component (image compression coding component)  16 , and a storage component (image recording component)  18  as a recording apparatus.  
         [0038]    In the present embodiment, the camera unit  12  is composed of four surveillance cameras  12   a - 12   d.    
         [0039]    The analog image signal of each of the cameras  12   a - 12   d  is digitized by A/D converters  20   a - 20   d  provided one for each camera  12   a - 12   d  and supplied to the image composition apparatus  14 .  
         [0040]    The image composition apparatus  14  comprises frame memory components  22   a - 22   d , provided one for each of the cameras  12   a - 12   d  for the purpose of storing the image signals from the respective cameras  12   a - 12   d  one frame at a time; a frame switch  24  for switching the order in which the image signals are input to an image processing component  28  to be described later; a frame memory read-out component  26  for controlling the read-out from the frame memory components  22   a - 22   d ; and an image processing component  28  for adjusting the resolution of the composite image obtained from the individual image signals read out from the frame memory components  22   a - 22   d.    
         [0041]    Additionally, the security camera recording system  10  is further equipped with an editing component  30 . The editing component  30  supplies a read clock signal and a read enable signal to the frame memory components  22   a - 22   d  so as to control the frame memory output gate, thus controlling the frame memory read-out component  26 . Additionally, the editing component  30  also supplies control signals to the image processing component  28  using image editing information such as the size of the composite image and the sizes of the individual images that form the composite image.  
         [0042]    The composite image signal formed by the image composition apparatus  14  described above is supplied to what is in this case an MPEG standard encoding component  16 . After the image signal so supplied is converted into a compression coded image signal it is recorded on a recording medium (not shown in the drawing) of the storage unit  18 .  
         [0043]    The reproduction component comprises a read-out component  32  (that is, a reproduction component) that reads the compression coded image signal from the recording medium of the storage unit  18 , a decoding component  34  that decodes the compression coded image signal, a frame selection component  36  (that is, an image selection component) that writes an arbitrarily selected image signal to the frame memory component, a frame memory unit  38  (that is, a selected image signal storage component), a D/A converter  40 , and a display monitor  42  (that is, an output component).  
         [0044]    A description will now be given of the operation of the security camera recording system  10 , and specifically, of first the recording operation and then the reproduction operation.  
         [0045]    As an initial matter, it should be noted that the individual cameras  12   a - 12   d  are positioned at different locations and photograph an image from different angles.  
         [0046]    The analog image signals from each of the cameras  12   a - 12   d  are digitized by the corresponding A/D converters  20   a - 20   d  and written to the corresponding frame memory components  22   a - 22   d , where they are stored.  
         [0047]    The editing component  30  sets editing parameters for the composite image to be recorded in the storage unit  18 . That is, the editing component selects the image signals from each of the cameras  12   a - 12   d  and supplies control signals to the frame memory read-out component  26  that control the order in which the image signals so selected are input. Then, based on the control signals from the editing component  30 , the frame memory read-out component  26  opens predetermined frame memory components  22   a - 22   d  output gates and generates a read clock (read clock signal). In so doing, selected image signals are supplied to the image processing component  28  via the frame switch  24 . The read clock rate can be changed as necessary by changing the composite image editing parameters, a point which will be described later.  
         [0048]    The image processing component  28  is supplied i with control signals based on image editing information such as the size of the composite image from the editing component and the size of the individual images that form the composite image so as to obtain a predetermined composite image signal.  
         [0049]    The composite image signal is then supplied to the encoding component  16  and converted into a compression coded image signal, after which it is recorded in the storage unit  18 .  
         [0050]    A description will now be given of four sample edited composite images, with reference to FIGS. 3A and 3B,  4 A and  4 B,  5 A and  5 B, and  6 A and  6 B.  
         [0051]    [0051]FIGS. 3A and 3B are diagrams illustrating a first sample composite image edited using one embodiment of the present invention, in which FIG. 3A shows the composite image formed by image signals of individual cameras and FIG. 3B shows a timing chart of same. In this case, it is only the second camera, that is, camera  12   b , that is being recorded.  
         [0052]    In this case, the input comes from the second camera only, that is, from camera  12   b  only, so the control signals from the editing component  30  determine that the frame switch  24  is fixed on the input line from camera  12   b  only. It should be noted that a normal image size, that is, a full size, is selected as the camera image size unless the camera image size is specifically delineated.  
         [0053]    [0053]FIGS. 4A and 4B are diagrams illustrating a second sample composite image edited by one embodiment of the present invention, in which FIG. 4A shows the composite image formed by image signals of individual cameras and FIG. 4B shows a timing chart of same. The drawing illustrates a case in which the image (frame) of the composite image (that is, the composite image signal) is divided into four regions, with the images (image signals) of the cameras  12   a - 12   d  positioned in each respective region.  
         [0054]    Thus, for example, when under normal conditions the image size of the image signals of each of the individual cameras  12   a - 12   d  is composed of 480×640 pixels, in FIG. 4A the image size of the composite image signal becomes 960×1280 pixels, amounting to four times the normal amount of information. Therefore in order to read the image signals from all four cameras  12   a - 12   d  within a predetermined time period used to process a single frame composite image signal, the read clock rate is in this case increased to four times the normal rate.  
         [0055]    The image signals of each individual frame memory components  22   a - 22   d  are read out in units of one line at a time in a horizontal line direction, with the composite image composed by controlling the timing of this read-out.  
         [0056]    That is, in the timing chart, when the first horizontal line of the image signal of the first camera  12   a  is read out, the frame switch  24  switches and the first horizontal line of the image signal of the second camera  12   b  is read out. Next, the frame switch  24  once again switches so as to read the second horizontal line of the image signal from the first camera  12   a , and the frame switch  24  switches yet again to read the second horizontal line from the second camera  12   b.    
         [0057]    In such manner, after the last horizontal line of the image signal of the second camera  12   b  is read out, the frame switch  24  switches so as to read the first horizontal line of the image signal of the third camera  12   c . Thereafter, in the same manner as with each of the image signals of the first camera  12   a  and the second camera  12   b , each of the horizontal lines of the image signals of the third camera  12   c  and the fourth camera  12   d  are read alternately. Then, the image signals of all the cameras  12   a - 12   d  are read out within the predetermined time period for processing a single frame image and a composite image is formed.  
         [0058]    [0058]FIGS. 5A and 5B are diagrams illustrating a third sample composite image edited by one embodiment of the present invention, in which FIG. 5A shows the composite image formed by image signals of individual cameras and FIG. 5B shows a timing chart of same.  
         [0059]    In this case, too, as with the case depicted in FIGS. 4A and 4B, the amount of composite image signal information is four times the normal amount, so the read clock rate is set to four times the normal rate.  
         [0060]    In the timing chart, after the first horizontal lines of the image signals have been read in sequence from the first horizontal line of the image signal of the first camera  12   a  to the first horizontal line of the image signal of the fourth camera  12   d , the second horizontal lines are read in sequence from the second horizontal line of the image signal of the first camera  12   a  to the second horizontal line of the image signal of the fourth camera  12   d . The read continues in like manner until the last horizontal line from each of the image signals of each of the cameras is read out to form a composite image signal.  
         [0061]    [0061]FIGS. 6A and 6B are diagrams illustrating a fourth sample composite image edited by one embodiment of the present invention, in which FIG. 6A shows the composite image formed by image signals of individual cameras and FIG. 6B shows a timing chart of same.  
         [0062]    In this case, too, in order to form an image from the four cameras  12   a  through  12   d , the read clock rate is set to four times the normal rate. The number of pixels in the images of each of the cameras  12   a - 12   d  is the same, so the speed with which image signals of each of the cameras  12   a - 12   d  is read is the same as well.  
         [0063]    The timing control sequence of the frame switch  24  is the same as that for the other examples described above, so a detailed description thereof will be omitted.  
         [0064]    The size of each image signal, in other words, the image signal resolution adjustment, is carried out by the image processing component  28 . Based on the image size information and image placement information as determined by the editing component  30 , the image processing component  28  processes the images signals of the cameras  12   a - 12   d  supplied via the frame switch  24  and adjusts the resolution so that the image signal corresponds to the selected image size.  
         [0065]    In the case depicted in FIGS. 6A and 6B, the process shown is that of reducing the resolution of the image signals of the cameras  12   a - 12   d .  
         [0066]    The above description pertains to the process of recording. The following description pertains to the process of reproducing the images of the four cameras  12   a    12   d  from the compression coded image signal recorded in the storage unit  18 .  
         [0067]    The compression coded image signal as a composite image signal is read from the recording medium of the storage unit  18  by the read-out component  32 .  
         [0068]    The read compression coded image signal is then decoded by the decoding component  34 .  
         [0069]    Then, the frame selection component  36  acquires only that image signal which is arbitrarily selected from among the decoded composite image signals and writes same to the frame memory unit  38 . Thereafter the image signals are displayed on the display monitor  42  via the D/A converter  40 . It should be noted that the image displayed at this time is a moving image, so anything happening in range of the camera can be observed.  
         [0070]    As can be appreciated by those skilled in the art, by providing only a single frame memory unit the composite image can be written directly as is without division to such frame memory unit, with the result that images from all the cameras can be displayed on a single display monitor at once. Additionally, by providing four frame memory units (as with the embodiments described above) the image signal is divided into an image signal for each of the cameras by the frame selection component, z written into each of the frame memory units provided for each respective image signal and displayed either selectively at a single display monitor or in an arbitrary sequence involving each of the cameras. Alternatively, a plurality of monitors may be provided and images of each camera displayed thereon.  
         [0071]    According to the above-described embodiments of the present invention, a plurality of image signals from a plurality of cameras can be optimally compression coded because there is a high degree of correlation between successive individual frames of the composite image signal so generated. In this case, each of the plurality of cameras acquires a different image from any of the others, so the conventional JPEG standard of encoding is unable to record a moving picture efficiently under such conditions.  
         [0072]    Additionally, the above-described embodiments of the present invention employ an editing component, so a desired image signal can be selected from among a plurality of image signals and a composite image signal can be edited using adjusted image size and resolution.  
         [0073]    The above description is provided in order to enable any person skilled in the art to make and use the invention and sets forth the best mode contemplated by the inventors of carrying out the invention.  
         [0074]    The present invention is not limited to the specifically disclosed embodiments, and variations and modifications may be made without departing from the scope and spirit of the present invention.  
         [0075]    The present application is based on Japanese Priority Application No. 2000-202255, filed on Jul. 4, 2000, the entire contents of which are hereby incorporated by reference.