Patent Publication Number: US-8126055-B2

Title: Telop detecting method, telop detecting program, and telop detecting device

Description:
TECHNICAL FIELD 
     The present invention relates to a telop detecting method, a telop detecting program, and a telop detecting device for detecting telops. However, use of the present invention is not limited to the above telop detecting method, the telop detecting program, and the telop detecting device. 
     BACKGROUND ART 
     Conventionally, a method is provided in which moving image data in which a telop portion of the moving image is encoded is directly extracted without decoding. This method includes a step of judging whether the encoded moving image data is a frame that is encoded using a correlation between frames or a frame that is encoded without using correlation between frames; a step of determining, for the frame that is encoded using a correlation between frames, whether a pixel therein is encoded without applying motion compensation; a step of storing an encoded value in a two-dimensional counting matrix corresponding to the position of the pixel; a step of comparing the value stored in each counting matrix with a threshold value; and a step of identifying a pixel having a value determined to be larger than the threshold value as the telop portion. Such an operation is executed to each pixel in a predetermined area, and the telop of the moving image can be extracted by reviewing the operations (see, for example, Patent Document 1 below). 
     A telop region detecting apparatus has been proposed that can detect appearance of a telop at a high speed and with high precision and can extract the position of the telop in a frame from compressed-encoded data itself or from information formed by encoding only a portion thereof. In the telop region detecting apparatus, only necessary information is decoded partially from the encoded data by a variable length decoding unit and the decoded information is delivered to a time change judging unit, a telop position judging unit, and an appearing frame judging unit. The time change judging unit sets in I picture a region that is a candidate telop region. The telop position judging unit picks up a block having an encoding mode suitable for the telop from the I picture. The appearing frame judging unit executes a frame judging process that judges from which frame the telop appears (see, for example, Patent Document 2 below). 
     Patent Document 1: Japanese Patent Application Laid-Open Publication No. H9-322173 
     Patent Document 2: Japanese Patent Application Laid-Open Publication No. 2002-64748 
     DISCLOSURE OF INVENTION 
     Problem to be Solved by the Invention 
     However, according to the conventional technique of Patent Document 1, generally, even a region that is between-frame-estimated without applying motion compensation may include a stationary region, and therefore, the region is not always a telop and a problem that the detection precision is degraded can be listed as an example. 
     According to the conventional technique of Patent Document 2, because the timing to detect a telop is limited to the time when the telop appears, a problem can be listed as an example that it is difficult to cope with a telop such as the one that appears in a specific way such as fading in or sequential appearance of characters, a telop that appears simultaneously with the change of scenes, or a small telop. 
     As a region other than that for a telop, regions are present that each have brightness and color difference varying often in a space region may be present and a problem can be listed as an example that it is difficult to distinguish these regions from a telop. 
     Means for Solving Problem 
     A telop detecting method as described herein includes an acquiring step of acquiring an intraframe predictive coded picture from a series of frames concerning a compressed-encoded moving image using an orthogonal transformation from a space region to a frequency region; an extracting step of extracting an arbitrary block from the intraframe predictive coded picture acquired at the acquiring step; a calculating step of calculating an evaluation value that indicates a possibility of a presence of a telop in the block by weighting a frequency component of an arbitrary frequency band in the block extracted at the extracting step, using a weighting matrix in which a value weighting a frequency component of another frequency band having higher frequency than the frequency band is high; and a detecting step of detecting a telop region that includes the telop from the frame based on the evaluation value calculated at the calculating step. 
     A telop detecting method as described herein includes a first intraframe predictive coded picture acquiring step of acquiring a first intraframe predictive coded picture from a series of frames concerning a moving image that is compressed-encoded using an orthogonal transformation from the space region to the frequency region; a first extracting step of extracting an arbitrary first block from the first intraframe predictive coded picture acquired at the first intraframe predictive coded picture acquiring step; a first calculating step of calculating a first evaluation value that indicates the possibility of including a telop in a first block by weighting a frequency component in the first block using a weighting matrix for which, compared to a value that weights a frequency component of an arbitrary frequency band in the first block extracted at the first extracting step, a value that weights a frequency component of another frequency band that is higher than the arbitrary frequency band in the block is higher, for the frequency component of an arbitrary frequency band in the first block extracted at the extracting step; a first detecting step of detecting a telop region including the telop from the first block based on the first evaluation value calculated at the first calculating step; an interframe predictive coded picture acquiring step of acquiring an interframe predictive coded picture input after the first intraframe predictive coded picture from the series of frames; a second extracting step of extracting a second block corresponding to an appearing position of the first block from the interframe predictive coded picture acquired at the interframe predictive coded picture acquiring step; an updating step of updating a frequency component of the first block from which the telop region has been detected at the first detecting step using a frequency component of the second block extracted at the second extracting step; a second intraframe predictive coded picture acquiring step of acquiring a second intraframe predictive coded picture input immediately after the first intraframe predictive coded picture acquiring from the series of frames; a third extracting step of extracting a third block corresponding to the appearing positions of the first and the second blocks from the second intraframe predictive coded picture acquired at the second intraframe predictive coded picture acquiring step; a second calculating step of calculating a second evaluation value that indicates the possibility of including the telop in the third block extracted at the third extracting step by weighting a frequency component updated at the updating step using the weighting matrix; and a second detecting step of detecting a telop region same as the telop region from the third block based on the second evaluation value calculated at the second calculating step. 
     A telop detecting method as described herein includes an interframe predictive coded picture acquiring step of acquiring an interframe predictive coded picture from a series of frames concerning a moving image that is compressed-encoded using an orthogonal transformation from the space region to the frequency region and a between-frame correlation; a macro block extracting step of extracting an arbitrary macro block to be noted (hereinafter, “notable macro block”) and at least any one macro block of macro blocks present surrounding the notable macro block (hereinafter, “surrounding macro block”) from the interframe predictive coded picture acquired at the interframe predictive coded picture acquiring step; a first calculating step of calculating an evaluation value that indicates the possibility of including a telop in the notable macro block based on a motion vector of the notable macro block extracted at the macro block extracting step and a motion vector of the surrounding macro block extracted at the first macro block extracting step; an intraframe predictive coded picture acquiring step of acquiring an intraframe predictive coded picture input after the interframe predictive coded picture from the series of frames; a block extracting step of extracting a block in the macro block corresponding to an appearing position of the notable block from the intraframe predictive coded picture acquired at the intraframe predictive coded picture acquiring step; a second calculating step of calculating a second evaluation value that indicates the possibility of including the telop in the block by weighting a frequency component in the block using a weighting matrix for which, compared to a value that weights a frequency component of an arbitrary frequency band in the block extracted at the block extracting step, a value that weights a frequency component of another frequency band that is higher than the arbitrary frequency band in the block is higher, for the frequency component of an arbitrary frequency band in the block extracted at the block extracting step; and a detecting step of detecting a telop region including the telop based on the first and the second evaluation values calculated at the first and the second calculating steps. 
     A telop detecting program as described herein causes a computer to execute an acquiring step of acquiring an intraframe predictive coded picture from a series of frames concerning a compressed-encoded moving image using an orthogonal transformation from a space region to a frequency region; an extracting step of extracting an arbitrary block from the intraframe predictive coded picture acquired at the acquiring step; a calculating step of calculating an evaluation value that indicates a possibility of a presence of a telop in the block by weighting a frequency component of an arbitrary frequency band in the block extracted at the extracting step, using a weighting matrix in which a value weighting a frequency component of another frequency band having higher frequency than the frequency band is high; and a detecting step of detecting a telop region that includes the telop from the frame based on the evaluation value calculated at the calculating step. 
     A telop detecting program as described herein causes a computer to execute a first intraframe predictive coded picture acquiring step of acquiring a first intraframe predictive coded picture from a series of frames concerning a moving image that is compressed-encoded using an orthogonal transformation from the space region to the frequency region; a first extracting step of extracting an arbitrary first block from the first intraframe predictive coded picture acquired at the first intraframe predictive coded picture acquiring step; a first calculating step of calculating a first evaluation value that indicates the possibility of including a telop in a first block by weighting a frequency component in the first block using a weighting matrix for which, compared to a value that weights a frequency component of an arbitrary frequency band in the first block extracted at the first extracting step, a value that weights a frequency component of another frequency band that is higher than the arbitrary frequency band in the block is higher, for the frequency component of an arbitrary frequency band in the first block extracted at the extracting step; a first detecting step of detecting a telop region including the telop from the first block based on the first evaluation value calculated at the first calculating step; an interframe predictive coded picture acquiring step of acquiring an interframe predictive coded picture input after the first intraframe predictive coded picture from the series of frames; a second extracting step of extracting a second block corresponding to an appearing position of the first block from the interframe predictive coded picture acquired at the interframe predictive coded picture acquiring step; an updating step of updating a frequency component of the first block from which the telop region has been detected at the first detecting step using a frequency component of the second block extracted at the second extracting step; a second intraframe predictive coded picture acquiring step of acquiring a second intraframe predictive coded picture input immediately after the first intraframe predictive coded picture acquiring from the series of frames; a third extracting step of extracting a third block corresponding to the appearing positions of the first and the second blocks from the second intraframe predictive coded picture acquired at the second intraframe predictive coded picture acquiring step; a second calculating step of calculating a second evaluation value that indicates the possibility of including the telop in the third block extracted at the third extracting step by weighting a frequency component updated at the updating step using the weighting matrix; and a second detecting step of detecting a telop region same as the telop region from the third block based on the second evaluation value calculated at the second calculating step. 
     A telop detecting program as described herein causes a computer to execute an interframe predictive coded picture acquiring step of acquiring an interframe predictive coded picture from a series of frames concerning a moving image that is compressed-encoded using an orthogonal transformation from the space region to the frequency region and a between-frame correlation; a macro block extracting step of extracting an arbitrary macro block to be noted (hereinafter, “notable macro block”) and at least any one macro block of macro blocks present surrounding the notable macro block (hereinafter, “surrounding macro block”) from the interframe predictive coded picture acquired at the interframe predictive coded picture acquiring step; a first calculating step of calculating an evaluation value that indicates the possibility of including a telop in the notable macro block based on a motion vector of the notable macro block extracted at the macro block extracting step and a motion vector of the surrounding macro block extracted at the first macro block extracting step; an intraframe predictive coded picture acquiring step of acquiring an intraframe predictive coded picture input after the interframe predictive coded picture from the series of frames; a block extracting step of extracting a block in the macro block corresponding to an appearing position of the notable block from the intraframe predictive coded picture acquired at the intraframe predictive coded picture acquiring step; a second calculating step of calculating a second evaluation value that indicates the possibility of including the telop in the block by weighting a frequency component in the block using a weighting matrix for which, compared to a value that weights a frequency component of an arbitrary frequency band in the block extracted at the block extracting step, a value that weights a frequency component of another frequency band that is higher than the arbitrary frequency band in the block is higher, for the frequency component of an arbitrary frequency band in the block extracted at the block extracting step; and a detecting step of detecting a telop region including the telop based on the first and the second evaluation values calculated at the first and the second calculating steps. 
     A telop detecting device as described herein includes an acquiring unit that acquires an intraframe predictive coded picture from a series of frames concerning a compressed-encoded moving image using an orthogonal transformation from a space region to a frequency region; an extracting unit that extracts an arbitrary block from the intraframe predictive coded picture acquired by the acquiring unit; a calculating unit that calculates an evaluation value that indicates a possibility of a presence of a telop in the block by weighting a frequency component of an arbitrary frequency band in the block extracted by the extracting unit, using a weighting matrix in which a value weighting a frequency component of another frequency band having higher frequency than the frequency band is high; and a detecting unit that detects a telop region that includes the telop from the frame based on the evaluation value calculated by the calculating unit. 
     A telop detecting device as described herein includes a first intraframe predictive coded picture acquiring unit that acquires a first intraframe predictive coded picture from a series of frames concerning a moving image that is compressed-encoded using an orthogonal transformation from the space region to the frequency region; a first extracting unit that extracts an arbitrary first block from the first intraframe predictive coded picture acquired by the first intraframe predictive coded picture acquiring unit; a calculating unit that calculates a first evaluation value that indicates the possibility of including a telop in a first block by weighting a frequency component in the first block using a weighting matrix for which, compared to a value that weights a frequency component of an arbitrary frequency band in the first block extracted at the first extracting step, a value that weights a frequency component of another frequency band that is higher than the arbitrary frequency band in the block is higher, for the frequency component of an arbitrary frequency band in the first block extracted by the extracting unit; a detecting unit that detects a telop region including the telop from the first block based on the first evaluation value calculated by the calculating unit; an interframe predictive coded picture acquiring unit that acquires an interframe predictive coded picture input after the first intraframe predictive coded picture from the series of frames; a second extracting unit that extracts a second block corresponding to an appearing position of the first block from the interframe predictive coded picture acquired by the interframe predictive coded picture acquiring unit; and an updating unit that updates a frequency component of the first block from which the telop region has been detected by the detecting unit using a frequency component of the second block extracted by the second extracting unit. The intraframe predictive coded picture acquiring unit acquires a second intraframe predictive coded picture input next to the first intraframe predictive coded picture from the series of frames, the first extracting unit extracts a third block corresponding to the appearing positions of the first and the second blocks from the second intraframe predictive coded picture acquired by the intraframe predictive coded picture acquiring unit, the calculating unit calculates a second evaluation value that indicates the possibility of including the telop in the third block extracted by the first extracting unit by weighting a frequency component updated by the updating unit using the weighting matrix, and the detecting unit detects a telop region same as the telop region, from the third block based on the second evaluation value calculated by the calculating unit. 
     A telop detecting device as described herein includes an interframe predictive coded picture acquiring unit that acquires an interframe predictive coded picture from a series of frames concerning a moving image that is compressed-encoded using an orthogonal transformation from the space region to the frequency region and a interframe correlation; a macro block extracting unit that extracts an arbitrary macro block to be noted (hereinafter, “notable macro block”) and at least any one macro block of macro blocks present surrounding the notable block (hereinafter, “surrounding macro block”) from the interframe predictive coded picture acquired by the interframe predictive coded picture acquiring unit; a first calculating unit that calculates an evaluation value that indicates the possibility of including a telop in the notable macro block based on a motion vector of the notable macro block extracted by the macro block extracting unit and a motion vector of the surrounding macro block extracted by the first macro block extracting unit; an intraframe predictive coded picture acquiring unit that acquires an intraframe predictive coded picture input after the interframe predictive coded picture from the series of frames; a block extracting unit that extracts a block in the macro block corresponding to an appearing position of the notable macro block from the intraframe predictive coded picture acquired by the intraframe predictive coded picture acquiring unit; a second calculating unit that calculates a second evaluation value that indicates the possibility of including the telop in the block by weighting a frequency component in the block using a weighting matrix for which, compared to a value that weights a frequency component of an arbitrary frequency band in the block extracted by the block extracting unit, a value that weights a frequency component of another frequency band that is higher than the arbitrary frequency band in the block is higher, for the frequency component of an arbitrary frequency band in the block extracted by the block extracting unit; and a detecting unit that detects a telop region including the telop based on the first and the second evaluation values calculated by the first and the second calculating units. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram of the functional configuration of a telop detecting device according to a first embodiment; 
         FIG. 2  is a diagram for explaining an example of a macro block weighted by a weighting matrix; 
         FIG. 3  is diagram for explaining a differential image; 
         FIG. 4  is a flowchart of a telop detecting process according to the first embodiment; 
         FIG. 5  is a block diagram of a functional configuration of a telop detecting device according to a second embodiment; 
         FIG. 6  is a flowchart of a telop detecting process according to the second embodiment; 
         FIG. 7  is a block diagram of a hardware configuration of the telop detecting device according to a first example; 
         FIG. 8  is a block diagram of a functional configuration of the telop detecting device according to the first example; 
         FIG. 9  is a flowchart of a telop detecting process according to the first example; 
         FIG. 10  is a flowchart of a DCT coefficient evaluating process; 
         FIG. 11  is a schematic view of a telop detecting process; 
         FIG. 12  is a block diagram of a functional configuration of the telop detecting device according to a second example; 
         FIG. 13  is a flowchart of a telop detecting process according to the second example; 
         FIG. 14  is a flowchart of a candidate telop region judging process; 
         FIG. 15  is a flowchart of a differential image DCT coefficient process; 
         FIG. 16  is a flowchart of a telop region judging process; 
         FIG. 17  is a schematic view of a telop detecting process of the second example; 
         FIG. 18  is a diagram for explaining an example of the difference between motion vectors; 
         FIG. 19  is a diagram for explaining another example of the difference between motion vectors; 
         FIG. 20  is a block diagram of the functional configuration of a telop detecting device according to a third example; 
         FIG. 21  is a flowchart of a telop detecting process according to the third example; 
         FIG. 22  is a flowchart of a motion vector evaluating process; 
         FIG. 23  is a flowchart of another DCT coefficient evaluating process; 
         FIG. 24  is a schematic view of a telop detecting process of the third embodiment; 
         FIG. 25  is a diagram for explaining the difference between motion vectors; and 
         FIG. 26  is another flowchart of the motion vector evaluating process. 
     
    
    
     EXPLANATIONS OF LETTERS OR NUMERALS 
     
         
           100 ,  500  telop detecting device 
           101 ,  504  intraframe predictive coded picture acquiring unit, 
           102  first extracting unit 
           103  calculating unit 
           104 ,  507  detecting unit 
           105 ,  508  judging unit 
           106 ,  509  determining unit 
           107 ,  501  interframe predictive coded picture acquiring unit 
           108  second extracting unit 
           109  updating unit 
           502  macro block extracting unit 
           503  first calculating unit 
           505  block extracting unit 
           510  discriminating unit 
           511  output unit 
       
    
     BEST MODE(S) FOR CARRYING OUT THE INVENTION 
     With reference to the accompanying drawings, exemplary embodiments of a telop detecting method, a telop detecting program, and a telop detecting device according to the present invention is explained in detail. 
     First Embodiment 
     (Functional Configuration of Telop Detecting Device) 
     Description will be given for a functional configuration of a telop detecting device according to a first embodiment.  FIG. 1  is a block diagram of the functional configuration of the telop detecting device according to the first embodiment. As shown in  FIG. 1 , a telop detecting device  100  includes an intraframe predictive coded picture acquiring unit  101 , a first extracting unit  102 , a calculating unit  103 , and a detecting unit  104 . The intraframe predictive coded picture acquiring unit  101  acquires a frame that is intraframe prediction coded from a series of frames concerning a moving image that is compressed-encoded. 
     The series of frames concerning the moving image is, specifically, a set of moving images that are compressed-encoded using orthogonal transformation from a space region to a frequency region. The series of frames of the moving image is, for example, a series of frame images that is compressed-encoded in the MPEG format, and configured by frames that are intraframe predictive coded (intraframe predictive coded pictures) and frames that are interframe predictive coded (interframe predictive coded pictures). The intraframe predictive coded picture acquiring unit  101  acquires an intraframe predictive coded picture from the series of frames. 
     The first extracting unit  102  extracts an arbitrary block from the intraframe predictive coded picture acquired by the intraframe predictive coded picture acquiring unit  101 . A “block” used herein is one unit region of an orthogonally transformed version of the acquired frame. Especially for the MPEG, the block is a unit item to execute a DCT and is image data of eight by eight dots constituted by DCT coefficients. The block constitutes a macro block of an intraframe predictive coded picture. More specifically, the block may be at least any one of four Y signals representing brightness information of six blocks (four Y signals, Cr signal, and Cb signal) constituting the macro block. However, the brightness information and the color difference information (Cr signal and Cb signal) may be extracted being combined or only the color difference signal may be extracted. 
     The calculating unit  103  calculates an evaluation value (hereinafter, “first evaluation value”) that indicates the possibility that a telop is included in the block, by weighting the DCT coefficient in the block extracted by the first extracting unit  102  using a weighting matrix. 
     The weighting matrix is a matrix for which, compared to a value that weights a DCT coefficient of an arbitrary frequency band in a block, a value that weights a DCT coefficient of another frequency band that is higher than the arbitrary frequency band in the block is higher. Description will be given for an example of a block weighted by the weighting matrix.  FIG. 2  is a diagram for explaining an example of a block weighted by a weighting matrix. 
     As shown in  FIG. 2 , for a DCT coefficient in a block  200 , the frequency becomes lower as the coefficient moves to the upper left and becomes higher as the coefficient moves to lower right. That is, a region  201  in the leftmost and uppermost portion has a DCT coefficient of a DC component and is a region having the lowest frequency. Other regions  202  to  205  each have a DCT coefficient of an AC component. In the regions  202  to  205 , regions divided according to frequency bands are present and the frequency becomes higher in order of the regions  202 ,  203 ,  204 , and  205 . These regions  201  to  205  are respectively referred to as frequency bands  201  to  205 . 
     Therefore, in the weighting matrix, weighting of a DCT coefficient (DCT component) for the frequency band  201  is set to be “zero”. Compared to a value that weights a DCT coefficient of the frequency band  202 , a value that weights DCT coefficients of the other frequency bands  203  to  205  that have higher frequencies than that of the frequency band  202  is set to be larger. 
     In addition, compared to a value that weights DCT coefficient of the frequency band  203 , a value that weights DCT coefficients of the other frequency bands  204  to  205  that have higher frequencies than that of the frequency band  203  is set to be larger. Compared to a value that weights a DCT coefficient of the frequency band  204 , a value that weights a DCT coefficient of the other frequency bands  205  that has higher frequencies than that of the frequency band  204  is set to be larger. 
     In this manner, by calculating a first evaluation value using a weighting matrix, the possibility that a telop is included in an image in a block can be represented as a numeral. Although the frequency bands  202  to  205  are formed by dividing the AC component of the DCT coefficient into four in  FIG. 2 , the number into which the AC component is divided may be in a region that is two or more. 
     Description will be given in detail for a telop. A telop is a caption or a picture superimposed on a natural image that is a series of frames constituting video contents. When a telop is present in a block, an edge (abrupt variation of a brightness value and a color difference value) is present on a border portion of a telop in the space region. 
     Because this is related to the visibility of a telop that is an information transmitting means utilizing the visual sense, this property is common to many telops. It is known that an image including such a steep edge as this has a value having a large absolute value that appears in a frequency component in a frequency band. Utilizing this property, the calculating unit  103  calculates the first evaluation value that is a value representing the possibility of including a telop as a numeral by further increasing a DCT coefficient using a weighting matrix for a high frequency component of the DCT coefficient. 
     The detecting unit  104  shown in  FIG. 1  detects a telop region including a telop therein from a block based on the first evaluation value calculated by the calculating unit  103 . More specifically, the detecting unit  104  includes a judging unit  105  and a determining unit  106 . The judging unit  105  judges whether the first evaluation value calculated by the calculating unit  103  is equal to or larger than a predetermined first threshold value. 
     When the first evaluation value is judged to be equal to or larger than the predetermined first threshold value, the determining unit  106  determines a block extracted by the first extracting unit  102  as a telop region. When the first evaluation value is judged not to be equal to or larger than the predetermined first threshold value, the determining unit  106  determines the block extracted by the first extracting unit  102  as a non-telop region. 
     According to the above configurations, focusing on a high-frequency component of a DCT coefficient to detect a steep edge that is a feature of a telop, a block may be extracted as a candidate telop when the value is large. Thereby, distinction between a “noisy part present in a natural image, having mainly a relatively low frequency component therein and a high DCT coefficient appearing therein” and a “telop part inserted artificially, having a high DCT coefficient that tends to appear in a high-frequency component” can be executed with higher precision. 
     The telop detecting device  100  includes an interframe predictive coded picture acquiring unit  107 , a second extracting unit  108 , and an updating unit  109 . The interframe predictive coded picture acquiring unit  107  acquires an interframe predictive coded picture input following an intraframe predictive coded picture (hereinafter, “first intraframe predictive coded picture” in the first embodiment) acquired by the intraframe predictive coded picture acquiring unit  101  from the series of frames. The interframe predictive coded picture is a P picture or a B picture following the first intraframe predictive coded picture. 
     The second extracting unit  108  extracts a block (hereinafter, “second block” in the first embodiment) corresponding to the appearing position of the block (hereinafter, “first block” in the first embodiment) extracted by the first extracting unit  102  from the interframe predictive coded picture acquired by the interframe predictive coded picture acquiring unit  107 . Similarly to the case of the first extracting unit  102 , the “block” refers to a unit region of the orthogonal transformation in the frame acquired. Especially, in the case of MPEG, a block is a unit region for executing DCT and is image data of eight by eight dots constituted by DCT coefficients. More specifically, this block constitutes a compressed encoded macro block of an interframe predictive coded picture. More specifically, this block may be at least any one of the four Y signals representing brightness information of the six blocks (four Y signals, Cr signal, Cb signal) constituting a macro block. However, the brightness information and the color difference information (Cr signal and Cb signal) may be extracted being combined or only the color difference signal may be extracted. 
     The updating unit  109  updates the DCT coefficient of the first block for which the detecting unit  104  has detected the telop region, using the DCT coefficient of the second block that the second extracting unit  108  has extracted. More specifically, the updating unit  109  updates the DCT coefficient of the first block determined to be the telop region by the determining unit  106  and retains the DCT coefficient after being updated. 
     When the second block extracted by the second extracting unit  108  and the first block are in the same position, the updating unit  109  updates the retained DCT coefficient using the DCT coefficient of the second block extracted by the second extracting unit  108 . The updating unit  109  executes this updating every time the second extracting unit  108  newly extracts another second block until the next intraframe predictive coded picture (I picture) is acquired. The specific updating process will be described later. 
     The intraframe predictive coded picture acquiring unit  101  acquires an intraframe predictive coded picture (hereinafter, “second intraframe predictive coded picture” in the first embodiment) input next to the first intraframe predictive coded picture from the series of frames. In this case, the first extracting unit  102  extracts a block (hereinafter, “third block” in the first embodiment) corresponding to the appearing position of the first block and the second block from the second intraframe predictive coded picture acquired by the intraframe predictive coded picture acquiring unit  101 . 
     Using the above weighting matrix, the calculating unit  103  calculates an evaluation value (hereinafter, “second evaluation value” in the first embodiment) indicating the possibility that a telop is included in the third block extracted by the first extracting unit  102  by weighting the DCT coefficient updated by the updating unit  109 . The specific calculation of the second evaluation value will be described later. 
     Based on the second evaluation value calculated by the calculating unit  103 , the detecting unit  104  detects a telop region same as the telop region from the third block. More specifically, the judging unit  105  judges whether the second evaluation value calculated by the calculating unit  103  is equal to or larger than a predetermined second threshold value. 
     When the judging unit  105  judges that the second evaluation value is equal to or larger than a predetermined second threshold value, the determining unit  106  determines the third block extracted by the first extracting unit  102  as the telop region that is same as the telop region of the preceding determination. 
     When the judging unit  105  judges that the second evaluation value is not equal to or larger than a predetermined second threshold value, the determining unit  106  determines the third block extracted by the first extracting unit  102  as a region that is not the telop region that is same as the telop region of the preceding determination. 
     More specifically, when a telop is included in the third block, the telop is a telop that is different from the telop included in the telop region determined by the first extracting unit  102 . Therefore, switching of the telop in the third frame can be detected. When no telop is included in the third frame, it can be detected that the telop of the first intraframe predictive coded picture is deleted in the second intraframe predictive coded picture. 
     In addition to the first intraframe predictive coded picture, these configurations use the DCT coefficient of the interframe predictive coded picture, that is, the DCT coefficient of a differential image between the frames, for detecting telops. In the MPEG, except an intra macro block, an interframe predictive coded picture is presented as a differential image between this image and the image that is the origin of the estimation and the DCT coefficient of the differential image is encoded. In this case, the case where the difference is zero is included. 
     Description will be given for a differential image.  FIG. 3  is diagram for explaining a differential image. As shown in  FIG. 3 , an edge  302  is present in an arbitrary position in an estimation origin image  301 . When the edge  302  has disappeared in an image (estimated image)  311  after the estimation, in a differential image  321  between the estimation origin image  301  and the estimated image  311 , a new edge  322  has generated in the same position as the position of the edge  302  in the estimation origin image  301 . The DCT coefficient of the differential image  321  generates with the same absolute value and in the same position as that of the DCT coefficient of the estimation origin image  301 . 
     Generally, once displayed, a telop stays still. From this fact, for a region that is judged to be a telop in a first frame that is intraframe prediction coded, due to the above nature of a telop, the precision of the telop detection can be improved by capturing the behavior of the edge from the DCT coefficient of a second frame that is interframe prediction coded. Thereby, a discontinuing point between telops can be detected when another telop is present continuously in the same position. 
     (Procedure of Telop Detecting Process) 
     Description will be given for a procedure of a telop detecting process according to the first embodiment.  FIG. 4  is a flowchart of the telop detecting process according to the first embodiment. As shown in  FIG. 4 , the first intraframe predictive coded picture that is intraframe prediction coded is acquired from a series of frames (step S 401 ). An arbitrary first block is extracted from the first intraframe predictive coded picture acquired (step S 402 ). 
     Using a weighting matrix, the first evaluation value that indicates the possibility that a telop is included in the first block extracted is calculated (step S 403 ). When this first evaluation value calculated is equal to or larger than the predetermined first threshold value (step S 404 : YES), the first block is determined to be a telop region (step S 405 ). When the first evaluation value is not equal to or larger than the predetermined first threshold value (step S 404 : NO), the first block is determined to be a non-telop region (step S 406 ). 
     Thereby, a noisy region that is present in a natural image and a telop region inserted artificially can be distinguished from each other and the telop region can be detected with high precision. The interframe predictive coded picture input after the first intraframe predictive coded picture is acquired from the series of frames (step S 407 ). The second block is extracted from the interframe predictive coded picture acquired (step S 408 ). 
     Using the DCT coefficient of the second block extracted at step S 408 , the DCT coefficient of the first block determined to be the telop region is updated (step S 409 ). Thereafter, when the next frame is an interframe predictive coded picture (step S 410 : YES), the procedure goes to step S 407 . 
     When the next frame is not an interframe predictive coded picture (step S 410 : NO), the second intraframe predictive coded picture is acquired (step S 411 ). The third block is extracted from the second intraframe predictive coded picture acquired (step S 412 ). 
     By weighting the DCT coefficient updated by the updating unit  109  using a weighting matrix, the second evaluation value that indicates the possibility that a telop is included in the third block extracted at step S 412  is calculated (step S 413 ). When the second evaluation value calculated is equal to or larger than a predetermined second threshold value (step S 414 : YES), the third block is determined to be the telop region same as the telop region determined at step S 405  (step S 415 ). 
     When the second evaluation value is not equal to or larger than the predetermined second threshold value (step S 414 : NO), the block is determined not to be a telop region same as the telop region determined at step S 405  (step S 416 ). Thereby, a discontinuing point between telops can be detected when another telop is present continuously in the same position. 
     Second Embodiment 
     (Functional Configuration of Telop Detecting Device) 
     Description will be given for a second embodiment. In the second embodiment, in addition to the evaluation of the DCT coefficients shown in the first embodiment, telop detection is executed using motion vectors. More specifically, in a region that displays a telop in an image, the shape of the telop does not vary over time and the telop is kept displayed spatially integrated. Therefore, in a macro block in the telop region, motion compensation is executed by uniform motion vectors including the case where the length of each of the motion vectors is “zero”. 
     For example, when the telop stays still, the motion compensation of the macro block including the telop is not executed (the motion vector is “zero”) while, when the telop is moving, the motion vectors of the macro block in the display region thereof are also uniformly reflect the direction and the velocity of the motion of the telop. Utilizing this, in the second embodiment, the evaluation of the possibility of including a telop is executed from the motion vectors concerning the surroundings of the macro block in the image. 
     Description will be given for a functional configuration of a telop detecting device according to the second embodiment.  FIG. 5  is a block diagram of a functional configuration of the telop detecting device according to the second embodiment. As shown in  FIG. 5 , a telop detecting device  500  includes an interframe predictive coded picture acquiring unit  501 , a macro block extracting unit  502 , a first calculating unit  503 , an intraframe predictive coded picture acquiring unit  504 , a block extracting unit  505 , a second calculating unit  506 , a detecting unit  507 , a discriminating unit  510 , and an output unit  511 . 
     The interframe predictive coded picture acquiring unit  501  acquires an interframe predictive coded picture from a series of frames of a moving image compressed-encoded using orthogonal transformation from a space region to a frequency region, and the between-frame correlation. The series of frames concerning the moving image is, for example, a series of frame images compressed-encoded in the MPEG format, and includes intraframe predictive coded frames (intraframe predictive coded pictures) and interframe predictive coded frames (interframe predictive coded pictures). 
     The macro block extracting unit  502  extracts an arbitrary macro block to be focused (hereinafter, “notable macro block”) and at least any one macro block of macro blocks present surrounding the notable macro block (hereinafter, “surrounding macro block”), from the interframe predictive coded picture acquired by the interframe predictive coded picture acquiring unit  501 . The “macro block” is a unit region for executing interframe prediction using the above interframe correlation and includes parameters indicating the encoding method of the macro block thereof and motion vectors used for the motion compensation. More specifically, a macro block includes six blocks of four Y signals, a Cr signal, and a Cb signal. A surrounding blocks may be eight macro blocks surrounding the notable macro block or may be four macro blocks adjacent to and on and beneath and to the left and right of each other. At least one of the surrounding blocks may be extracted. 
     The first calculating unit  503  calculates a evaluation value (hereinafter, “first evaluation value” in the second embodiment) indicating the possibility that a telop is included in the notable macro block based on a motion vector of the notable macro block extracted by the macro block extracting unit  502  and a motion vector of the surrounding macro block extracted by the macro block extracting unit  502 . The first evaluation value can be calculated based on the difference between the motion vector of the notable macro block and the motion vector of the surrounding macro block. 
     For example, the first evaluation value may be the number of times the difference between the motion vectors being “zero” or may be the total value of the differences. The calculation of the difference between the motion vectors will be described later. In addition to the difference between the motion vectors and the total value of the differences, the degree of motion compensation may be calculated from the motion vector length and the motion vector code length. 
     The intraframe predictive coded picture acquiring unit  504  shown in  FIG. 5  acquires an intraframe predictive coded picture input after an interframe predictive coded picture from the series of frames. The block extracting unit  505  extracts a block in a macro block corresponding to an appearing position of the notable macro block from the in-frame estimated encoded image. As to the description for the block extracted is same as that of the above first embodiment, and therefore, is omitted. 
     The second calculating unit  506  calculates an evaluation value (hereinafter, “second evaluation value” in the second embodiment) that indicates the possibility that a telop is included in the block, by weighting the DCT coefficient in the block extracted by the block extracting unit  305  using a weighting matrix. The calculation of the weighting matrix and the calculation of the second evaluation value are same as those in the first embodiment, and therefore, are omitted. 
     The detecting unit  507  detects a telop region that includes a telop based on the first evaluation value and the second evaluation value calculated respectively by the first calculating unit  503  and the second calculating unit  505 . That is, a telop region is detected that is present in each frame from the interframe predictive coded picture to the intraframe predictive coded picture. 
     More specifically, the detecting unit  507  includes a judging unit  508  and a determining unit  509 . The judging unit  508  judges whether the first evaluation value is equal to or larger than a predetermined first threshold value, and based on this judgment result of the first evaluation value, also judges whether the second evaluation value is equal to or larger than a predetermined second threshold value. 
     The determining unit  509  determines the notable block to be a telop region based on the judgment results of the first evaluation value and the second evaluation value judged by the judging unit  508 . Candidate telop regions can be narrowed from the notable macro blocks by the judging unit  508 . A telop region can be detected from the notable macro blocks that are listed as the candidate telop regions. Thereby, the telop region of telops that appear continuously between frames can be detected. 
     The discriminating unit  510  discriminates whether the telop in the telop region detected by the detecting unit  507  is a stationary telop or a roll telop based on the motion vector of the notable macro block extracted by the macro block extracting unit  502  and the motion vector of the surrounding macro blocks extracted by the macro block extracting unit  502 . More specifically, the discrimination is executed using the direction and the vector length of the motion vectors in the telop region. A specific exemplary discrimination will be described later. The output unit  511  outputs the discrimination result discriminated by the discriminating unit  510 . 
     (Procedure of Telop Detecting Process) 
     Description will be given for a procedure of a telop detecting process according to the second embodiment.  FIG. 6  is a flowchart of a telop detecting process according to the second embodiment. As shown in  FIG. 6 , an interframe predictive coded picture is acquired from a series of frames (step S 601 ). From the interframe predictive coded picture, an arbitrary notable macro block and macro blocks surround the arbitrary notable macro block are extracted (step S 602 ). 
     Based on the motion vector of the notable macro block and the motion vectors of the surrounding macro blocks, a first evaluation value indicating the possibility that a telop is included in the notable macro block is calculated (step S 603 ). Thereafter, an intraframe predictive coded picture input after the interframe predictive coded picture is acquired (step S 604 ). A block is extracted from the interframe predictive coded picture acquired (step S 605 ). 
     Using a weighting matrix, the second evaluation value that indicates the possibility that a telop is included in the block is calculated by weighting the DCT coefficient in the block extracted at step S 605  (step S 606 ). A telop region including a telop is detected based on the first evaluation value calculated at step S 603  and the second evaluation value calculated at step S 606  (step S 607 ). 
     Whether the telop in the telop region detected by the detecting unit  507  is a stationary telop or a roll telop is discriminated based on the motion vector of the notable macro block extracted by the macro block extracting unit  502  and the motion vector of the surrounding macro blocks extracted by the macro block extracting unit  502  (step S 608 ). The discrimination result is output (step S 609 ). 
     According to the second embodiment, a stationary telop and a roll telop can be detected without discriminating those telops from each other because the motion vector difference is used. The discriminating unit  510  can also discriminate whether a stationary telop or a roll telop for a telop in a telop region detected without discriminating the type of the telop. 
     First Example 
     Description will be given for a first example of a telop detecting device. The telop detecting device according to the first example is an example of the telop detecting device according to the above first embodiment. 
     (Hardware Configuration of Telop Detecting Device) 
     Description will be given for the hardware configuration of the telop detecting device according to the first example.  FIG. 7  is a block diagram of a hardware configuration of the telop detecting device according to the first example. As shown in  FIG. 7 , the telop detecting device includes a CPU  701 , a ROM  702 , a RAM  703 , an HDD (Hard Disk Drive)  704 , an HD (Hard Disk)  705 , a CD/DVD drive  706 , a CD/DVD  707  as an example of a detachable recording medium, a video/audio I/F (interface)  708 , a display  709 , a speaker  710 , an input I/F (interface)  711 , a remote control unit  712 , input keys (including a keyboard or a mouse)  713 , and a communication I/F (interface)  714 . The above components  701  to  714  are respectively connected by a bus  700  to each other. 
     The CPU  701  administers the control of the entire telop detecting device. The ROM  702  stores programs such as a boot program. The RAM  703  is used by the CPU  701  as a work area. The HDD  704  controls reading/writing of data from/to the HD  705  according to the control of the CPU  701 . The HD  705  stores data written according to the control of the HDD  704 . 
     The CD/DVD drive  706  controls reading/writing of data from/to the CD/DVD  707  according to the control of the CPU  701 . The CD/DVD  707  is a detachable recording medium from which data recorded according to the control of the CD/DVD drive  706  is read. A writable recording medium can be used as the CD/DVD  707 . As a detachable recording medium, in addition to the CD/DVD  707 , a CD-ROM (CD-R, CD-RW), an MO, or a memory card may be used. 
     The video/audio I/F  708  is connected to the display  709  for video display and the speaker  710  for audio output. In addition to a cursor, icons, menus, windows, or tool boxes, the display  709  displays various types of data such as characters, videos, etc. A CRT, a TFT liquid crystal display, or a plasma display, for example, may be employed as the display  709 . Sound is output from the speaker  710 . 
     The input I/F  711  inputs data transmitted from the remote control unit  712  or the input keys  713  that include a plurality of keys to input characters, numerals, various instructions, etc. The input keys  713  include keys to input characters, numerals, various instructions, etc., and input data according to operations of a user. 
     The communication I/F  714  is connected to a network  720  by wireless or through a communication line and is connected to other apparatuses through the network  720 . In addition to the Internet, the network  720  may be a LAN, a WAN, a public line network, a portable telephone network, or a television broadcasting network such as television broadcasting stations. The communication I/F  714  administers the interface between the network  720  and the CPU  701  and controls transmission and reception of data to/from external apparatuses. The communication I/F  714  includes a tuner, and can select television stations and receive video contents. 
     (Functional Configuration of Telop Detecting Device) 
     Description will be given for a functional configuration of the telop detecting device according to the first example.  FIG. 8  is a block diagram of the functional configuration of the telop detecting device according to the first example. As shown in  FIG. 8 , a telop detecting device  800  includes an MPEC input source  801 , a parameter acquiring unit  802 , a switch  803 , a DCT coefficient evaluating unit  804 , and a result output unit  805 . 
     The MPEC input source  801  is a medium to acquire an MPEG stream. An MPEG stream includes a series of frames concerning a moving image compressed in the MPEG compressing encoding format such as, for example, video contents. 
     The series of frames includes a frame that is intraframe prediction coded (hereinafter, “intraframe predictive coded picture”) and a frame that is interframe prediction coded (hereinafter, “interframe predictive coded picture”). Each frame consists of a plurality of macro blocks and each of the macro blocks is compressed-encoded. 
     The MPEG input source  801  may be any medium that can acquire an MPEG stream such as the HD  705 , an optical disk such as the CD/DVD  707 , a storage device  811  that stores data in advance such as a flash memory, the network such as the IP or the IEEE 1394, and a receiver apparatus  812 , etc., for broadcasting, shown in  FIG. 7 . 
     The parameter acquiring unit  802  interprets an MPEG stream input from the MPEG input source  801 , extracts an intraframe predictive coded picture from the MPEG stream, and acquires parameters necessary for detecting a telop. 
     Parameters are information on the image type of the frame extracted and the DCT coefficient of each block. The information on the image type of the frame is information indicating whether the frame extracted is an intraframe predictive coded picture or an interframe predictive coded picture, and is attached to the header of each frame. 
     The parameter acquiring unit  802  corresponds to the intraframe predictive coded picture acquiring unit  101  shown in  FIG. 1 , and more specifically, realizes the function thereof, for example, by the CPU  701  executing a program stored in a recording medium such as the ROM  702 , the RAM  703 , the HD  705 , and the CD/DVD  707  shown in  FIG. 7 , or by the communication I/F  714 . 
     The switch  803  turns on and outputs to the DCT coefficient evaluating unit  804  the DCT coefficient retained by a block in the intraframe predictive coded picture when the frame acquired by the parameter acquiring unit  802  is intraframe prediction coded. When the frame acquired is interframe prediction coded, the switch  803  turns off and cancels the connection with the DCT coefficient evaluating unit  804 . More specifically, the switch  803  turns on or off by referring to the information of the image type attached to the header of each frame. 
     The switch  803  corresponds to the intraframe predictive coded picture acquiring unit  101  and the first extracting unit  102  shown in  FIG. 1 , and more specifically, realizes the function thereof by, for example, the CPU  701  executing a program stored in a recording medium such as the ROM  702 , the RAM  703 , the HD  705 , and the CD/DVD  707  shown in  FIG. 7 . 
     The DCT coefficient evaluating unit  804  evaluates the possibility that a telop is included from the DCT coefficient of each block in the frame acquired through the switch  803 , and judges and outputs a telop region. More specifically, the DCT coefficient evaluating unit  804  weights the DCT coefficient of each block using a weighting matrix W and calculates evaluation values. 
     That is, M×N DCT coefficients constituting each block are represented as a matrix C and each element thereof is represented as Cij (1≦i, j≦8). Cij is the DCT coefficient in i-th line and in j-th column of the matrix C. The weighting matrix W is also an eight by eight matrix corresponding to a block and each element thereof is represented as Wij (1≦i, j≦8). Wij is a weighting parameter in i-th line and in j-th column of the weighting matrix W. 
     As expressed in the following Equation (1), after weighting the absolute value |Cij| of the DCT coefficient Cij by multiplying the absolute value |Cij| by the weighting parameter Wij of the weighting matrix W, the total value is calculated. This total value is an evaluation value v. The evaluation value v corresponds to the first evaluation value in the above first embodiment. 
     
       
         
           
             
               
                 
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     Description will be given in detail for the weighting matrix W. As above, the weighting matrix W is a matrix for which, compared to a value that weights a DCT coefficient of an arbitrary frequency band in a block, a value is higher that weights a DCT coefficient of another frequency band including frequencies that are higher than those of the arbitrary frequency band. That is, the weighting matrix W is a matrix with which the weighting parameter becomes larger for the DCT coefficient of a higher frequency component in the DCT coefficients of an AC component in a block. An example of the weighting matrix W will be listed. 
     
       
         
           
             
               
                 
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     Each weighting parameter Wij of the weighting matrix W of the Equation (2) corresponds to the DCT coefficient of a block. That is, the weighting parameter W 11  that corresponds to the DCT coefficient C 11  is “zero”. The weighting parameters Wij (i, j≠1) corresponding to the DCT coefficients Cij (i, j≠1) of the AC component are “1”, “2”, “4”, and “8” in order of increasing frequency of the AC component. 
     The weighting matrix W of Equation (2) is an example and does not limit the matrix to be used for weighting. However, to evaluate by causing large values to appear in the high-frequency component, the matrix is configured to have a larger weighting parameter Wij for the DCT coefficient Cij (i, j≠1) of a DCT higher-frequency component. Another weighting matrix W may be considered to be, for example, a matrix of the following Equation (3). 
     
       
         
           
             
               
                 
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     The DCT coefficient evaluating unit  804  judges whether the evaluation value v calculated is equal to or larger than a threshold value Vth. Based on the judgment result, whether the block is a telop region including a telop is determined. Thereby, the telop region can be detected. This telop region detection result is output for input to another apparatus or a program that uses the telop region detection result, storage in a memory or a storage device, transmission through a network, and a user interface such as a screen. 
     The DCT coefficient evaluating unit  804  corresponds to the calculating unit  103  and the detecting unit  104  shown in  FIG. 1 , and more specifically, realizes the function thereof by, for example, executing by the CPU  701  of the program stored in a recording medium such as the ROM  702 , the RAM  703 , the HD  705 , and the CD/DVD  707  shown in  FIG. 7 . 
     The result output unit  805  outputs the telop detection evaluation result in the form of a binary matrix for each block for one frame every time an intraframe predictive coded picture is processed. For example, when the image resolution is 720×480 pixels, a matrix of the size 90×60 is output because a block has a size of eight dots×eight dots. The value of each of the matrixes is “one” when, for example, a telop region is judged in the DCT coefficient evaluation and is “zero” when a non-telop region is judged. When color difference information is used, each color difference signal block of 16 dots×16 dots may be output. 
     The result output unit  805  corresponds to the detecting unit  104  shown in  FIG. 1 , and more specifically, realizes the function thereof by, for example, executing by the CPU  701  of the program stored in a recording medium such as the ROM  702 , the RAM  703 , the HD  705 , and the CD/DVD  707  or by the communication I/F  714  shown in  FIG. 7 . 
     (Procedure of Telop Detecting Process) 
     Description will be given for a procedure of a telop detecting process according to the first example.  FIG. 9  is a flowchart of the telop detecting process according to the first example. As shown in  FIG. 9 , when an MPEG stream is input (step S 901 : YES), a frame at the head is acquired from the MPEG stream (step S 902 ). 
     The image type of the frame acquired is identified from information on the image type of the frame acquired (step S 903 ). In this case, when the image type of the frame acquired is between-frame estimation encoding (step S 903 : NO), the switch  803  is turned off and the procedure moves to step S 906 . 
     When the image type of the frame acquired is in-frame estimation encoded (step S 903 : YES), the switch  803  is turned on and a DCT coefficient evaluating process is executed (step S 904 ). Thereafter, the evaluation result of the DCT coefficient evaluating process is output (step S 905 ). 
     When all of the frames are not yet acquired (step S 906 : NO), the procedure goes to step S 902  and the next frame is acquired. When all of the frames are acquired (step S 906 : YES), the series of process steps are finished. 
     Description will be given in detail for the DCT coefficient evaluating process procedure at step S 904 .  FIG. 10  is a flowchart of the DCT coefficient evaluating process. In  FIG. 10 , the frames acquired are scanned and the number of blocks is N and the block number k is k=1 (step S 1001 ). The evaluation value v is initialized (v=0) (step S 1002 ) and a block Bk is extracted (step S 1003 ). 
     Using Equation (1), the evaluation value v is calculated by multiplying the absolute value |Cij| of each DCT coefficient Cij of the extracted block Bk by the weighting parameter Wij in the same position as that of the DCT coefficient Cij (step S 1004 ). Whether the evaluation value v is equal to or larger than the threshold value Vth is judged (step S 1005 ). 
     When the evaluation value v is equal to or larger than the threshold value Vth (step S 1005 : YES), the block Bk is determined as a telop region including a telop (step S 1006 ). When the evaluation value v is not equal to or larger than the threshold value Vth (step S 1005 : NO), the block Bk is determined as a non-telop region that does not include a telop (step S 1007 ). 
     Thereafter, when k is not k=N (step S 1008 : NO), k is incremented (step S 1009 ) and the procedure moves to step S 1002 . When k is k=N (step S 1008 : YES), the DCT coefficient evaluating process is finished. 
     Description will be given schematically for the above telop detecting process.  FIG. 11  is a schematic view of a telop detecting process. In  FIG. 11 , steps corresponding to those in  FIG. 9  are given the corresponding step numbers shown in  FIG. 9 . 
     In  FIG. 11 , an MPEG stream  1100  is a series of frames of a moving image compressed according to the MPEG compressing-encoding format, and is constituted of intraframe predictive coded pictures  1101  and  1103 , and an interframe predictive coded picture  1102 . The MPEG steam  1100  is input from the MPEG input source  801 . 
     Assuming that a restored image  1111  of the intraframe predictive coded picture  1101  includes a telop  1121  (“a, i, u, e, o”), the evaluation value v of the block Bk (shaded block in  FIG. 11 ) corresponding to the appearing position of a telop  1121  of the block Bk of the frame  1101  acquired from the MPEG steam  1100  is equal to or larger than the threshold value Vth and a telop region  1131  can be detected from the frame  1101 . 
     Assuming that the restored image  1111  of the frame  1103  includes no telop, all the evaluation value v of the block Bk of the intraframe predictive coded picture  1103  acquired from the MPEG steam  1100  are not equal to or larger than the threshold value Vth and no telop region is detected from the intraframe predictive coded picture  1103 . 
     In this manner, according to the above first example, at the time when an intraframe predictive coded picture appears, a telop region can be detected using only the DCT coefficient of a block of the frame. In other words, without using an interframe predictive coded picture, the fact that an edge that is a feature of a telop appears (in a high-frequency component in the DCT coefficient of the AC component) as a feature of a frequency band is used. 
     Therefore, a telop region and a non-telop region can be separated from each other with higher precision and improvement of the telop detection precision can be facilitated. Therefore, it is possible to prevented erroneous detection of a stationary region of an object other than a telop as a telop region. 
     According to the first example, because not the appearance of a telop but the fact that the telop is being displayed is detected, the telop can be traced as far as the telop is displayed and improvement of the detection precision can be facilitated. Therefore, the timing for detecting the telop is not limited to the time when the telop appears, and such a telop can be detected easily as the one that appears in a specific way such as fading in or sequential appearance of characters, a telop that appears simultaneously with the change of scenes, or a small telop. 
     According to the first example, because a steep edge is detected by weighting a high-frequency component of the DCT coefficient of the AC component of a block, a telop region can be detected with higher precision. Therefore, a non-telop region including no telop and with considerably varying brightness and color difference, and a telop region including a telop can be easily distinguished from each other and the telop region can be easily detected. 
     In the above first example, the DCT coefficient evaluating process is not limited to the above method. For example, the evaluation value v may be calculated by extracting the maximal value MAX{|Cij|Wij} of values |Cij|Wij obtained by weighting the absolute values |Cij| of the DCT coefficients Cij by the weighting parameter Wij for each frequency band of the block Bk and summing the representative value MAX{|Cij|Wij} extracted of each frequency band. 
     More specifically, for example, a weighting matrix W as expressed by the following Equation (4) is prepared, and such that in the weighting matrix W, a weighting parameter Wij in the same position as the value of the weighting parameter Wij is regarded as one frequency band individually, the DCT coefficients of the block Bk are divided such that the coefficients correspond to the frequency bands. 
     
       
         
           
             
               
                 
                   [ 
                   
                     Equation 
                     ⁢ 
                     
                         
                     
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                     4 
                   
                   ] 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   W 
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                     ) 
                   
                 
               
               
                 
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     In each frequency band in the block Bk, the value MAX{|Cij|Wij} obtained by multiplying the maximal value of the absolute value MAX{|Cij|} of the DCT coefficient Cij by the weighting parameter Wij of the same frequency band of the weighting matrix W of the above Equation (4) is the representative value of the frequency band. A value obtained by totaling the representative values of all the frequency bands is the evaluation value that represents the possibility of including a telop of the block Bk. According to this evaluating approach, the same effect as above effect can also be obtained. 
     Second Example 
     Description will be given for a telop detecting device according to a second example next. The telop detecting device according to the second example is an example of the telop detecting device  100  according to the above first embodiment. The telop detecting device according to the second example is a telop detecting device that can detect discontinuity between telops that are in the same position between sequential frames. Because the hardware configuration of the telop detecting device according to the second example is same as the hardware configuration of the telop detecting device  800  according to the first embodiment shown in  FIG. 7 , the description thereof is omitted. 
     (Functional Configuration of Telop Detecting Device) 
     Description will be given for a functional configuration of the telop detecting device according to the second example.  FIG. 12  is a block diagram of the functional configuration of the telop detecting device according to the second example. The components same as the components of the first example shown in  FIG. 8  are given the same reference numerals and the description thereof is omitted. 
     A shown in  FIG. 12 , a telop detecting device  1200  includes the MPEG input source  801 , the result output unit  805 , a parameter acquiring unit  1201 , a switch  1202 , a candidate telop region judging unit  1203 , a differential image DCT coefficient processing unit  1204 , a memory  1205 , and a telop region judging unit  1206 . 
     The parameter acquiring unit  1201  interprets an MPEG stream input from the MPEG input source  801 , extracts an intraframe predictive coded picture and an interframe predictive coded picture from the MPEG stream, and acquires parameters necessary for detecting a telop. Similarly to the first example, parameters are information on the image type of the frames extracted and the DCT coefficient of each block. The information on the image type of the frame is information indicating whether the frame extracted is an intraframe predictive coded picture or interframe predictive coded picture, and is attached to the header of each frame. 
     The parameter acquiring unit  1201  corresponds to the intraframe predictive coded picture acquiring unit  101  and the interframe predictive coded picture acquiring unit  107  shown in  FIG. 1 , and more specifically, realizes the function thereof, for example, by the CPU  701  executing a program stored in a recording medium such as the ROM  702 , the RAM  703 , the HD  705 , and the CD/DVD  707  shown in  FIG. 7 , or by the communication I/F  714 . 
     The switch  1202  connects to the candidate telop region judging unit  1203  and outputs a DCT coefficient of the intraframe predictive coded picture when the image type of the frame acquired by the parameter acquiring unit  1201  is the intraframe prediction coded type. When the image type of the frame acquired by the parameter acquiring unit  1201  is the interframe prediction coded type, the switch  1202  connects to the differential image DCT coefficient processing unit  1204  and outputs a DCT coefficient of the interframe predictive coded picture, that is, a differential image. 
     The switch  1202  corresponds to the intraframe predictive coded picture acquiring unit  101 , the first extracting unit  102 , the interframe predictive coded picture acquiring unit  107 , and the second extracting unit  108  shown in  FIG. 1 , and more specifically, realizes the function thereof, for example, by executing by the CPU  701  of a program stored in a recording medium such as the ROM  702 , the RAM  703 , the HD  705 , and the CD/DVD  707  shown in  FIG. 7 . 
     The candidate telop region judging unit  1203  judges from the DCT coefficient of a block in the intraframe predictive coded picture whether the block is a candidate telop region. More specifically, an evaluation value v 1  is calculated using the above weighting matrix W. That is, the evaluation value V 1  is calculated by multiplying the DCT coefficient Cij by the weighting parameter Wij of the weighting matrix W using the following Equation (5). 
     
       
         
           
             
               
                 
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     Whether the evaluation value v 1  is equal to or larger than a predetermined threshold value V 1   th  is judged. When the evaluation value v 1  is equal to or larger than the threshold value V 1   th , the block is determined to be a candidate telop region, and when the evaluation value v 1  is not equal to or larger than the threshold value V 1   th , the block is determined to be a non-telop region. The DCT coefficient Cij of the block that is a candidate telop region is output to a memory and is retained as a retained DCT coefficient Dij. 
     The candidate telop region judging unit  1203  corresponds to the calculating unit  103  and the detecting unit  104 , and more specifically, realizes the function thereof, for example, by the CPU  701  executing a program stored in a recording medium such as the ROM  702 , the RAM  703 , the HD  705 , and the CD/DVD  707  shown in  FIG. 7 . 
     The differential image DCT coefficient processing unit  1204  extracts the DCT coefficient Cij of a block in an interframe predictive coded picture (differential image) and updates the retained DCT coefficient Cij of the block in the previous intraframe predictive coded picture stored in the memory  1205 . 
     More specifically, when the position of the block in the previous intraframe predictive coded picture stored in the memory  1205  and the position of the block in the interframe predictive coded picture (differential image) are the same, the absolute value |Cij| of the DCT coefficient Cij of the block in the interframe predictive coded picture (the differential image) is subtracted from the retained DCT coefficient Dij and the subtraction result is retained again in the memory as a new retained DCT coefficient Dij. 
     The differential image DCT coefficient processing unit  1204  corresponds to the updating unit  109  shown in  FIG. 1 , and more specifically, realizes the function thereof, for example, by the CPU  701  executing of a program stored in a recording medium such as the ROM  702 , the RAM  703 , the HD  705 , and the CD/DVD  707  shown in  FIG. 7 . 
     The memory  1205  stores the retained DCT coefficient Dij. The memory  1205  corresponds to the updating unit  109  shown in  FIG. 1 , and more specifically, realizes the function thereof, for example, by a recording medium such as the ROM  702 , the RAM  703 , the HD  705 , and the CD/DVD  707  shown in  FIG. 7 . 
     The telop region judging unit  1206  judges and outputs a telop region from the retained DCT coefficient Dij accumulated in the memory by a process for the intraframe predictive coded picture input immediately before and the interframe predictive coded picture input thereafter. 
     More specifically, the unit  1206  calculates the weighting parameter Wij of the weighting matrix W by multiplying the retained DCT coefficient Dij by the weighting parameter Wij of the weighting matrix W, and calculates an evaluation value v 2  by totaling respective Dij·Wij. However, depending on the quantity of the DCT coefficients Cij generated in the differential image, the updated retained DCT coefficient Dij may be a negative number, and in that case, the value of Dij·Wij is regarded as “zero”. 
     
       
         
           
             
               
                 
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     Whether the evaluation value v 2  is equal to or larger than a predetermined threshold value V 2   th  is judged. When the evaluation value v 2  is equal to or larger than the threshold value V 2   th , this block is determined as a telop region. When the evaluation value v 2  is not equal to or larger than the threshold value V 2   th , the block is determined as a non-telop region. 
     The telop region judging unit  1206  corresponds to the calculating unit  103  and the detecting unit  104  shown in  FIG. 1 , and more specifically, realizes the function thereof, for example, by a recording medium such as the ROM  702 , the RAM  703 , the HD  705 , and the CD/DVD  707  shown in  FIG. 7 . 
     (Procedure of Telop Detecting Process) 
     Description will be given to a procedure of a telop detecting process according to the second example.  FIG. 13  is a flowchart of the telop detecting process according to the second example. When an MPEG stream is input (step S 1301 : YES), a frame at the head is acquired from the MPEG stream (step S 1302 ). 
     The image type of the frame acquired is identified from information on the image type of the frame acquired (step S 1303 ). In this case, when the image type of the frame acquired is between-frame estimation encoding (step S 1303 : NO), if all the frames have been acquired (step S 1304 : YES), the series of process steps are finished. If not all the frames have been acquired (step S 1304 : NO), the procedure moves to step S 1302 . 
     When the image type of the frame acquired at step S 1302  is intraframe prediction coding at step  1303  (step S 1303 : YES), a candidate telop region judging process is executed (step S 1305 ). When all the frames have been acquired (step S 1306 : YES), the series of process steps are finished. 
     When not all of the frames are acquired (step S 1306 : NO), the next frame is acquired (step S 1307 ). When the image type of the frame acquired at step S 1307  is the interframe prediction coding (step S 1308 : YES), a differential image DCT coefficient process is executed (step S 1309 ). After executing the differential image DCT coefficient process, the procedure moves to step S 1306 . 
     When the image type of the frame acquired at step S 1307  is the in-frame estimation encoding (step S 1308 : NO), the telop region judging process is executed (step S 1310 ). The telop detection result for the frame acquired at step S 1307  is output (step S 1311 ) and the procedure goes to step S 1306 . 
     Description will be given in detail for a procedure of the candidate telop region judging process at step S 1305  shown in  FIG. 13 .  FIG. 14  is a flowchart of the candidate telop region judging process. In  FIG. 14 , the acquired frame is scanned and the number of blocks is represented as N and the block number k is k=1 (step S 1401 ). The evaluation value v 1  is initialized (v 1 =0) (step S 1402 ) and a block Bk is extracted (step S 1403 ). 
     Using Equation (5), the evaluation value v 1  is calculated by multiplying the absolute value |Cij| of each DCT coefficient Cij of the extracted block Bk by the weighting parameter Wij in the same position as that of the DCT coefficient Cij (step S 1404 ). Whether the evaluation value v 1  is equal to or larger than the threshold value V 1   th  is judged (step S 1405 ). 
     When the evaluation value v 1  is equal to or larger than the threshold value V 1   th  (step S 1405 : YES), the block Bk is determined as a candidate telop region (step S 10406 ). The DCT coefficient Cij of the block is retained in the memory  1205  as the retained DCT coefficient Dij (step S 1407 ). Thereafter, the procedure moves to step S 1409 . 
     When the evaluation value v 1  is not equal to or larger than the threshold value V 1   th  at step S 1405  (step. S 1405 : NO), the block Bk is determined as a candidate non-telop region (step S 1408 ). When k is not k=N (step S 1409 : NO), k is incremented (step S 1410 ) and the procedure moves to step S 1402 . When k is k=N (step S 1409 : YES), the candidate telop region judging process is finished. 
     Description will be given for the differential image DCT coefficient process procedure at step S 1309  shown in  FIG. 13 .  FIG. 15  is a flowchart of the differential image DCT coefficient process procedure. In  FIG. 15 , the acquired frame is scanned and the number of blocks is represented as N and the block number k is k=1 (step S 1501 ). The block Bk is extracted (step S 1502 ). 
     Whether the position on the frame of the block Bk is same as the position on the frame of a block Bm (block number: m=1, 2, . . . ) determined as the candidate telop region is judged (step S 1503 ). This judgment can be judged by, for example, checking whether the block number k of the block Bk and the block number m of the block Bm coincide with each other. 
     When the block numbers do not coincide (step S 1503 : NO), the procedure moves to step S 1505 . When the block numbers coincide (step S 1503 : YES), the absolute value |Cij| of the DCT coefficient Cij of the block Bk is used to be subtracted from the retained DCT coefficient Dij stored in the memory, and the retained DCT coefficient Dij is updated (step S 1504 ). 
     When k is not k=N (step S 1505 : NO), k is incremented (step S 1506 ) and the procedure moves to step S 1502 . When k is k=N (step S 1505 : YES), the differential image DCT coefficient process is finished. 
     Description will be given for a procedure of the telop region judging process at step S 1310  shown in  FIG. 13 .  FIG. 16  is a flowchart of the telop region judging process. In  FIG. 16 , the acquired frame is scanned and the number of blocks is represented as N and the block number k is k=1 (step S 1601 ). The evaluation value v 2  is initialized (v 2 =0) (step S 1602 ) and the block Bk is extracted (step S 1603 ). 
     Whether the position on the frame of the block Bk is same as the position on the frame of a block Bm (block number: m=1, 2, . . . ) determined as the candidate telop region is judged (step S 1604 ). This judgment can be judged by, for example, checking whether the block number k of the block Bk and the block number m of the block Bm coincide with each other. 
     When the block numbers do not coincide (step S 1604 : NO), the procedure moves to step S 1609 . When the block numbers coincide (step S 1604 : YES), the evaluation value v 2  is calculated using the retained DCT coefficient Dij and (the weighting parameter Dij of) the weighting matrix W and according to the above Equation (6) (step S 1605 ). 
     Whether the evaluation value v 2  calculated is equal to or larger than the threshold value V 2   th  is judged (step S 1606 ). When the evaluation value v 2  is equal to or larger than the threshold value V 2   th  (step S 1606 : YES), the telop region of the current intraframe predictive coded picture is determined as the telop region same as that of the intraframe predictive coded picture immediately before (step S 1607 ). That is, the fact that the same telop appears in the same position can be detected in the frames from the one at the time when the intraframe predictive coded picture immediately before has appeared to the one of the current intraframe predictive coded picture. 
     When the evaluation value v 2  is not equal to or larger than the threshold value V 2   th  (step S 1606 : NO), the telop region of the current intraframe predictive coded picture is determined to be in a region different from the telop region of the intraframe predictive coded picture immediately before (step S 1608 ). That is, the fact that the telop is switched in the same position in the series of interframe predictive coded picture input since the intraframe predictive coded picture immediately before has appeared can be detected. 
     When k is not k=N (step S 1609 : NO), k is incremented (step S 1610 ) and the procedure moves to step S 1602 . When k is k=N (step S 1609 : YES), the telop region judging process is finished. 
     Description will be given schematically for the telop detecting process of the above second example.  FIG. 17  is a schematic view of a telop detecting process of the second example. In  FIG. 17 , the processes corresponding to those of  FIGS. 13 to 16  are given the step numbers shown in  FIGS. 13 to 16 . 
     In  FIG. 17 , an MPEG stream  1700  is a series of frames concerning a moving image compressed according to the MPEG compressing encoding format, and includes intraframe predictive coded pictures  1701  and  1704  and a series of interframe predictive coded pictures  1702 . The MPEG stream  1700  is input from the MPEG input source  801  shown in  FIG. 12 . 
     Assuming that a restored image  1711  of the intraframe predictive coded picture  1701  includes a telop  1721  (“a, i, u, e, o”), the evaluation value v 1  of the block Bk (shaded block in  FIG. 17 ) corresponding to the appearing position of a telop  1721  of the block Bk of the intraframe predictive coded picture  1701  acquired from the MPEG steam  1700  is equal to or larger than the threshold value V 1   th  and a candidate telop region  1731  can be detected from the intraframe predictive coded picture  1701 . 
     Assuming that, in the interframe predictive coded picture  1703  in the series of interframe predictive coded pictures  1702 , a restored image  1713  of the interframe predictive coded picture  1703  includes a telop  1723  (“ka, ki, ku, ke, ko”), the retained DCT coefficient Dij obtained from the intraframe predictive coded picture  1701  is updated by being subtracted by the DCT coefficient Cij of a block Bk (shaded block in  FIG. 17 ) corresponding to the appearing position of the telop  1723  of the block Bk of the interframe predictive coded picture  1703  (step S 1504 ). 
     Therefore, this means that, in the series of interframe predictive coded pictures  1702  from the appearance of the intraframe predictive coded picture  1701  immediately before to the new input of the intraframe predictive coded picture  1704 , the edge that is the judgment factor of the candidate telop region  1731  of the intraframe predictive coded picture  1701  immediately before has been canceled. 
     Thereby, in the intraframe predictive coded picture  1704  that has newly appeared, the candidate telop region  1731  of the intraframe predictive coded picture  1701  immediately before is not detected and the discontinuing point between telops can be detected. 
     Assuming that a telop  1721  (“a, i, u, e, o”) same as that of the intraframe predictive coded picture  1701  is present in the same position in the restored image  1713  of the interframe predictive coded picture  1703 , the value of the DCT coefficient Cij of the block Bk (shaded block in  FIG. 17 ) corresponding to the appearing position of the telop  1723  of the block Bk of the interframe predictive coded picture  1703  is “zero” or a very small value. 
     Therefore, the retained DCT coefficient Cij obtained from the intraframe predictive coded picture  1701  is almost not reduced and a (candidate) telop region  1731  same as that of the intraframe predictive coded picture  1701  can be detected in the new intraframe predictive coded picture  1704 . 
     In this manner, according to the above second example, whether an edge keeps appearing without any change in the same position in the space region can be judged by detecting whether a DCT coefficient having a large value in an interframe predictive coded picture has appeared in the same position as that of the DCT coefficient (of mainly a high frequency) that is the factor of the evaluation judgment of the DCT coefficient by an intraframe predictive coded picture. 
     Therefore, improvement of the telop detection precision can be facilitated. Especially, when telops are displayed sequentially in the same position, the position of the edge varied by the change of characters can be detected. 
     It is not limit the method to the above method. For example, in the telop region judgment, the method of totaling only the coefficient of the maximal value for each frequency band as described in the first example may be used to the method of evaluating the retained DCT coefficient Dij. Instead of subtracting sequentially by the DCT coefficient Cij that appears in the interframe predictive coded picture, it may be judged whether a DCT coefficient Cij that sufficiently large compared to the retained DCT coefficient Dij has appeared at least once. 
     Third Example 
     Description will be given for a telop detecting device according to a third example. The telop detecting device according to the third example is an example of the telop detecting device  500  according to the above second embodiment. A hardware configuration of the telop detecting device according to the third example is same as the hardware configuration of the telop detecting device  800  according to the first example, and therefore, the description thereof is omitted. 
     In addition to the evaluation of the DCT coefficients, the telop detecting device according to the third example executes the telop detection utilizing the differential value between motion vectors. Description will be given in detail for the difference between the motion vectors. 
       FIG. 18  is a diagram for explaining an example of the difference between motion vectors.  FIG. 18  is a diagram for estimation of a frame on the right (an estimated frame  1810 ) from a frame on the left (a reference frame  1800 ). The reference frame  1800  and the estimated frame  1810  each display a stationary telop “a, i, u, e, o”. Two macro blocks of the estimated frame  1810  should be noted. 
     The two macro blocks  1811  and  1812  are adjacent to each other and it is assumed that the one macro block  1811  is a notable macro block and the other macro block  1812  is a surrounding macro block. The two macro blocks  1811  and  1812  are estimated from the same positions as those of macro blocks  1801  and  1802  in the reference frame  1800 . 
     The shape of a portion of the stationary telop “a, i, u, e, o” included in both of the macro blocks  1811  and  1812  in the estimated frame  1810  is identical with the shape of a portion of the stationary telop “a, i, u, e, o” in the same position in the macro blocks  1801  and  1802  of the reference frame. Therefore, no variation is present between the reference frame  1800  and the estimated frame  1810 . 
     Therefore, the vector lengths of the motion vectors  1821  and  1822  of the two macro blocks  1811  and  1812  in the estimated frame  1810  are same (in this case, both “zero”). Therefore, the difference between the motion vectors  1821  and  1822  of the two macro blocks  1811  and  1812  is also “zero”. Therefore, it can be seen that the notable macro block  1811  is likely to be a telop. 
       FIG. 19  is a diagram for explaining another example of the difference between motion vectors.  FIG. 19  is also a diagram for estimation of a frame on the right (an estimated frame  1910 ) from a frame on the left (a reference frame  1900 ). In  FIG. 19 , the reference frame  1900  and the estimated frame  1910  both display objects P 1  to P 4 , and by varying the positions thereof between the frames, the objects P 1  to P 4  are represented as the objects P 1  to P 4  that move irregularly. Macro blocks in the estimated frame  1910  are focused. 
     The two macro blocks  1911  and  1912  are adjacent to each other and it is assumed that the one macro block  1911  is a notable macro block and the other macro block  1912  is a surrounding macro block. The two macro blocks  1911  and  1912  are estimated from positions different from those of macro blocks  1901  and  1902  in the reference frame  1900 . 
     That is, the image in the notable macro block  1911  of the estimated frame  1910  is an image obtained by a move of the macro block  1901  in the reference frame  1900  following the object P 3  of the reference frame  1900 , and the amount of the move is provided as a motion vector  1921 . Similarly, the image in the surrounding macro block  1912  of the estimated frame  1910  is an image obtained by a move of the macro block  1902  in the reference frame  1900  following the object P 4  of the reference frame  1900 , and the amount of the move is provided as a motion vector  1922  that is different from the motion vector  1921 . 
     Therefore, because the two macro blocks  1911  and  1912  adjacent to each other of the estimated frame  1910  are estimated from the two macro blocks  1901  and  1902  that are not adjacent to each other of the reference frame  1900 , the motion vectors  1921  and  1922  of the two macro blocks  1911  and  1912  adjacent to each other of the estimated frame  1910  are different from each other. Therefore, the difference between the two motion vectors  1921  and  1922  is not “zero” and it can be seen that the notable macro block  1911  is not likely to be a telop. 
     (Functional Configuration of Telop Detecting Device) 
     Description will be given for a functional configuration of the telop detecting device according to the third example.  FIG. 20  is a block diagram of the functional configuration of the telop detecting device according to the third example. The components same as the components of the first example shown in  FIG. 8  are given the same reference numerals and the description thereof is omitted. 
     As shown in  FIG. 20 , a telop detecting device  2000  includes the MPEG input source  801 , the result output unit  805 , a parameter acquiring unit  2001 , a switch  2002 , a motion vector evaluation processing unit  2003 , a memory  2004 , a DCT coefficient evaluating unit  2005 , and a telop discriminating unit  2006 . 
     The parameter acquiring unit  2001  interprets an MPEG stream input from the MPEG input source  801 , and acquires parameters necessary for detecting a telop by extracting an intraframe predictive coded picture and an interframe predictive coded picture from the MPEG stream. Similarly to the first example, the parameters in this case also include motion vectors in addition to the information on the image type of the frame extracted and the DCT coefficient of each block. The information on the image type of a frame is information indicating whether the frame extracted is an intraframe predictive coded picture or an interframe predictive coded picture, and is attached to the header of each frame. 
     The parameter acquiring unit  2001  corresponds to the interframe predictive coded picture acquiring unit  501  and the intraframe predictive coded picture acquiring unit  504  shown in  FIG. 5 , and more specifically, realizes the function thereof, for example, by the CPU  701  executing of a program stored in a recording medium such as the ROM  702 , the RAM  703 , the HD  705 , and the CD/DVD  707  shown in  FIG. 7 , or by the communication I/F  714 . 
     The switch  2002  connects to the DCT coefficient judging unit  2005  and outputs a DCT coefficient Cij of the intraframe predictive coded picture when the image type of the frame acquired by the parameter acquiring unit  2001  is the intraframe prediction coded type. When the image type of the frame acquired by the parameter acquiring unit  2001  is the interframe prediction coded type, the switch  2002  connects to the motion vector evaluation processing unit  2003  and outputs a motion vector of the interframe predictive coded picture. 
     The switch  2002  corresponds to the interframe predictive coded picture acquiring unit  501 , the macro block extracting unit  502 , the intraframe predictive coded picture acquiring unit  504 , and the block extracting unit  505  shown in  FIG. 5 , and more specifically, realizes the function thereof, for example, by the CPU  701  executing of a program stored in a recording medium such as the ROM  702 , the RAM  703 , the HD  705 , and the CD/DVD  707  shown in  FIG. 7 . 
     The motion vector evaluation processing unit  2003  calculates a total value T of motion vectors based on the differences of the above motion vectors and stores temporarily the calculation result in the memory  2004 . For the total value T of the motion vectors, the total value T may be calculated from not only the differences between the motion vectors but also motion vector lengths and motion vector code lengths. 
     The motion vector evaluation processing unit  2003  corresponds to the first calculating unit  503  shown in  FIG. 5 , and more specifically, realizes the function thereof, for example, by the CPU  701  executing of a program stored in a recording medium such as the ROM  702 , the RAM  703 , the HD  705 , and the CD/DVD  707  shown in  FIG. 7 . 
     The memory  2004  stores the total value T of the motion vectors calculated by the motion vector evaluation processing unit  2003 . The total value T of the motion vectors is extracted by the DCT coefficient evaluating unit  2005  and is used in the DCT coefficient evaluating process. The memory  2004  corresponds to the first calculating unit  503  and the second calculating unit  506  shown in  FIG. 1 , and more specifically, realizes the function thereof, for example, by a recording medium such as the ROM  702 , the RAM  703 , the HD  705 , and the CD/DVD  707  shown in  FIG. 7 . 
     The DCT coefficient evaluating unit  2005  evaluates the DCT coefficient of an intraframe predictive coded picture in the same approach as that of the first example. More specifically, the DCT coefficient evaluating unit  2005  calculates the evaluation value v by weighting the DCT coefficient Cij of each block in the intraframe predictive coded picture acquired through the switch  2002  using the weighting matrix W, and evaluates the DCT coefficient Cij using the evaluation value v calculated and the total value T stored in the memory  2004 . Thereby, a telop region can be detected. 
     The DCT coefficient evaluating unit  2005  corresponds to the first calculating unit  503  and the detecting unit  507  shown in  FIG. 5 , and more specifically, realizes the function thereof, for example, by the CPU  701  executing of a program stored in a recording medium such as the ROM  702 , the RAM  703 , the HD  705 , and the CD/DVD  707  shown in  FIG. 7 . 
     The telop discriminating unit  2006  discriminates whether the telop in the telop region detected by the DCT coefficient evaluating unit  2005  is a stationary telop or a roll telop based on the motion vector of the notable macro block and the motion vector of the surrounding macro blocks thereof. More specifically, the discrimination is executed using the direction and the vector length of the motion vectors in the telop region. 
     The telop discriminating unit  2006  corresponds to the judging unit  510  shown in  FIG. 5 , and more specifically, realizes the function thereof, for example, by the CPU  701  executing of a program stored in a recording medium such as the ROM  702 , the RAM  703 , the HD  705 , and the CD/DVD  707  shown in  FIG. 7 . 
     (Procedure of Telop Detecting Process) 
     Description will be given for a procedure of telop detecting process according to the third example.  FIG. 21  is a flowchart of the telop detecting process procedure according to the third example. When an MPEG stream is input (step S 2101 : YES), a frame at the head is acquired from the MPEG stream (step S 2102 ). 
     The image type of the frame acquired is identified from information on the image type of the frame acquired (step S 2103 ). In this case, when the image type of the frame acquired is between-frame estimation encoding (step S 2103 : YES), a motion vector evaluating process is executed (step S 2104 ). 
     When not all of the frames are acquired (step S 2105 : NO), the procedure goes to step S 2102  and the next frame is acquired. When all of the frames are acquired (step S 2105 : YES), the series of process steps are finished. 
     When the image type of the frame acquired is in-frame estimation encoding (step S 2103 : NO), the DCT coefficient evaluating process is executed (step S 2106 ). The result of the telop detection is output (step S 2107 ). Thereafter, the telop is discriminated (step S 2108 ) and the procedure moves to step S 2105 . This discrimination process of the telop will be described later. 
     Description will be given for a procedure of the motion vector evaluating process at step S 2104  shown in  FIG. 21 .  FIG. 22  is a flowchart of the motion vector evaluating process procedure. As shown in  FIG. 22 , for the frame acquired at step S 2102  (the interframe predictive coded picture), the number of macro blocks is N, the macro block number k is k=1, and the total value T is T=0 (step S 2201 ). 
     The notable macro block Bk and the surrounding macro block Bc thereof are extracted (step S 2202 ). The difference Sk between the motion vector of the notable macro block Bk and the motion vector of the surrounding macro block Bc thereof are calculated (step S 2203 ). 
     When the difference Sk between the motion vectors is zero (step S 2204 : YES), the total value T is incremented (step S 2205 ) and the procedure moves to step S 2206 . When the difference Sk between the motion vectors is not zero (step S 2204 : NO), the procedure moves to step S 2206  without incrementing the total value T. 
     When k is not k=N (step S 2206 : NO), k is incremented (step S 2207 ) and the procedure moves to step S 2202 . When k is k=N (step S 2206 : YES), the motion vector evaluating process is finished. 
     Description will be given for the DCT coefficient evaluating process procedure at step S 2106  shown in  FIG. 21 .  FIG. 23  is a flowchart of the DCT coefficient evaluating process procedure. In  FIG. 23 , the acquired frame is scanned, and the number of blocks is N and the block number k is k=1 (step S 2301 ). The evaluation value v is initialized (v=0) (step S 2302 ) and the block Bk is extracted (step S 2303 ). 
     Using Equation (1), the evaluation value v is calculated by multiplying the absolute value |Cij| of each DCT coefficient Cij of the extracted block by the weighting parameter Wij in the same position as that of the DCT coefficient Cij (step S 2304 ). Whether the evaluation value v is equal to or larger than the threshold value Vth is judged (step S 2305 ). 
     When the evaluation value v is equal to or larger than the threshold value Vth (step S 2305 : YES), whether the total value T calculated at step S 2205  is equal to or larger than the threshold value Tth thereof is judged (step S 2306 ). The total value T calculated at step S 2205  is the total value of the macro block including the block. When the total value T is equal to or larger than the threshold value Tth thereof (step S 2306 : YES), the block Bk is determined as the telop region (step S 2307 ). 
     When the evaluation value v is not equal to or larger than the threshold value Vth at step S 2305  (step S 2305 : NO), or when the total value T is not equal to or larger than the threshold value Tth thereof (step S 2306 : NO), the block Bk is determined as the non-telop region (step S 2308 ). 
     When k is not k=N (step S 2309 : NO), k is incremented (step S 2310 ) and the procedure moves to step S 2302 . When k is k=N (step S 2309 : YES), the DCT coefficient evaluating process is finished. 
     Description will be given schematically for the telop detecting process of the above third example.  FIG. 24  is a schematic view of a telop detecting process of the third embodiment. In  FIG. 24 , process steps corresponding to those in  FIG. 21  are given the same step numbers as those shown in  FIG. 21 . 
     In  FIG. 24 , an MPEG stream  2400  is a series of frames concerning a moving image compressed according to the MPEG compressing encoding format, and includes intraframe predictive coded pictures  2401  and  2402 , and a series of interframe predictive coded pictures  2403 . The MPEG steam  2400  is input from the MPEG input source  801 . 
     Noting an arbitrary interframe predictive coded picture  2404  of the series of interframe predictive coded picture  2403 , a restored image  2414  thereof includes an object  2424  and a telop  2434  (“a, i, u, e, o”). 
     When the motion vector evaluating process (S 2104 ) is executed to the interframe predictive coded picture  2404  acquired at steps S 2102  and S 2103 , a set  2444  of the notable macro blocks Bk that have made the same move as that of the surrounding macro block Bc is detected. The set  2444  of the notable macro blocks Bk is a set of the notable macro blocks Bk for which the difference between the blocks Bk and the surrounding macro block Bc is “zero” and the number of the notable macro blocks Bk with the difference of “zero” is counted as the total value T. It is assumed that the object  2424  mostly is stationary or uniformly moves spatially. 
     Noting an interframe predictive coded picture  2405  immediately after the interframe predictive coded picture  2404 , a restored image  2415  thereof includes an object  2425  and the telop  2434  (“a, i, u, e, o”). 
     When the motion vector evaluating process (S 2104 ) is executed to the interframe predictive coded picture  2405  acquired at steps S 2102  and S 2103 , a set  2445  of the notable macro blocks Bk that have made the same move as that of the surrounding macro blocks Bc is detected. The set  2445  of the notable macro blocks Bk is a set of the notable macro blocks Bk for which the difference between the blocks Bk and the surrounding macro block Bc is “zero” and the number of the notable macro blocks Bk with the difference of “zero” is further counted as the total value T. It is assumed that the object  2425  mostly is stationary or uniformly moves spatially. 
     The motion vector evaluating process (S 2104 ) is continued until the intraframe predictive coded picture  2402  newly appears. When the intraframe predictive coded picture  2402  is acquired, the telop region of the intraframe predictive coded picture  2402  is detected using the total value T of the whole series of interframe predictive coded picture  2403 . 
     More specifically, it is assumed that a restored image  2412  of the intraframe predictive coded picture  2402  includes an object  2422  and a telop  2434  (“a, i, u, e, o”). When the evaluation value v of the macro block Bk (shaded block in  FIG. 24 ) corresponding to the appearing position of the telop  2434  of the block Bk of the intraframe predictive coded picture  2402  acquired in the DCT counting evaluating process (S 2106 ) is equal to or larger than the threshold value Vth and the total value T of whole the series of interframe predictive coded pictures  2403  is equal to or larger than the threshold value Tth for the macro block to which the block Bk belongs, a telop region  2442  including the telop  2434  can be detected in the intraframe predictive coded picture  2402 . 
     Therefore, in the third example, whether the motion vector has a nature of including a telop is judged for each position of a macro block while the interframe predictive coded pictures sequentially continue, and the number of times of appearance of the nature of including a telop is counted. When an intraframe predictive coded picture appears, for this intraframe predictive coded picture, a telop region is judged in the same method as that of the first example and whether the total value T of the counts between the previous intraframe predictive coded picture and the current one in the macro block to which each block of the telop belongs is equal to or larger than the threshold value Tth, that is, whether the number of times of appearance of the frames having a motion vector suggesting the possibility of a telop is large is judged. A region that satisfies both of the above is detected as a telop region. 
     Description will be given in detail for the difference between the motion vectors together with the discrimination of a detected telop.  FIG. 25  is a diagram for explaining the difference between the motion vectors. In  FIG. 25 , two restored images  2501  and  2502  are images having the identical backgrounds and objects. A stationary telop  2511  is present in the restored image  2501  and a roll telop  2512  that runs from the right to the left on the screen is present in the restored image  2502 . 
     In an image  2521  obtained by compensating the motion of the interframe predictive coded picture of the restored image  2501 , no motion compensation in a telop region  2531  corresponding to the position of the stationary telop  2511  is executed, that is, the motion vector value is zero. For the image  2541  formed by taking the difference between the motion vectors of the notable macro block and the surrounding macro block in the motion-compensated image  2521 , the difference between the motion vectors in the telop region  2531  corresponding to the position of the stationary telop  2511  is also “zero”. 
     Because the roll telop  2512  runs from the right to the left on the screen, in the image  2522  obtained by executing the motion compensation to the interframe predictive coded picture of the restored image  2502 , the motion vectors in the telop region  2532  corresponding to the position of the roll telop  2512  are uniform. In this case, the motion vectors all are “oriented to the right” and have the length of “two”. 
     However, for the image  2542  formed by taking the difference between the motion vectors of the notable macro block and the surrounding macro block in the motion-compensated image  2522 , the difference between the motion vectors in the telop region  2532  corresponding to the position of the roll telop  2512  is also “zero”. 
     Therefore, in the third example, by using the difference between the motion vectors, regardless of whether a stationary telop or a roll telop, a telop can be detected. Because the difference between the motion vectors is “zero” for both of a stationary telop and a roll telop, the telop type can not be discriminated. However, noting the motion-compensated images  2521  and  2522 , the motion vector length is zero in the image  2521  because no motion compensation has been executed, however, non-zero-motion vectors uniformly appear in the image  2522 . 
     Therefore, even in the case where the difference between the motion vectors for the detected telop is “zero”, a telop in a telop region detected can be discriminated as a roll telop when the motion vectors are non-zero in the motion compensation. 
     In the above motion vector evaluating process, the difference between the motion vector of the notable macro block Bk and the motion vector of the surrounding macro block Bc is calculated and the number of times at which the difference is “zero” is used as the coefficient of the total value T. However, the values of the difference between the motion vector of the notable macro block Bk and the motion vector of the surrounding macro block Bc may be counted without processing the values and the differences may be accumulated. 
     Description will be give for the motion vector evaluating process in this case.  FIG. 26  is another flowchart of the motion vector evaluating process procedure. In  FIG. 26 , the steps same as those in  FIG. 22  are given the same step numbers and the description thereof is omitted. After step S 2203 , the total value T is updated by adding the difference Sk between the motion vectors to the total value T (step S 2601 ). Thereafter, the procedure moves to step S 2206 . 
     Because the total value T is an accumulated value of the differences Sk in this motion vector evaluating process procedure, the branching after step S 2306  shown in  FIG. 23  is inversed. That is, when the evaluation value v is equal to or larger than the threshold value Vth (step S 2305 : YES) and the total value T is not equal to or larger than the threshold value Tth (step S 2306 : NO), the macro block Bk is determined as a telop region. When the evaluation value v is not equal to or larger than the threshold value Vth (step S 2305 : NO) or the total value T is equal to or larger than the threshold value Tth (step S 2306 : YES), the macro block Bk is determined as a non-telop region. 
     That is, though this motion vector evaluating process procedure uses the motion vectors of the interframe predictive coded picture, the values for judging whether the motion vectors suggest the possibility of a telop for the positions of the macro blocks are accumulated while the interframe predictive coded pictures continue. For example, the differences Sk between the motion vectors of the notable macro blocks Bk and the motion vectors of the surrounding macro blocks Bc are accumulated. 
     When the intraframe predictive coded picture appears, for this intraframe predictive coded picture, the telop region is judged in the same method as that of the first example, and whether the total value T accumulated between the previous intraframe predictive coded picture and the intraframe predictive coded picture currently appearing is equal to or larger than the threshold value Tth is judged. The block is determined as a telop region based on both of the judgment results. 
     In this manner, according to the third example, by utilizing the difference between the motion vectors, regions gathering together in one in an image can be extracted relatively easily. Thereby, regions that continue irregularly can be distinguished from a telop region and improvement of the precision of the telop region detection can be facilitated. 
     By using the motion compensation, simultaneously with a stationary telop, a telop moving regularly (for example, a running telop such as a staff roll) can also be detected. Depending on the manner of encoding, in most macro blocks, motion vectors are encoded by the difference value between the motion vector and that of the adjacent macro block. Therefore, this process can be realized with very small load and in a simple method. 
     The telop detecting method described in the embodiment can be realized by executing a program prepared in advance on a computer such as a personal computer or a work station. This program is recorded in a computer-readable recording medium such as a hard disk, a flexible disk, a CD-ROM, an MO, a DVD, and is executed by being read from the recording medium by the computer. This program may be a transmission medium distributable through a network such as the Internet. 
     As above, the telop detecting method, the telop detecting program, and the telop detecting device according to the embodiments are useful for a digital video recorder (a DVD recorder, an HDD recorder, an HDD/DVD recorder), a home server, a car navigating apparatus, a computer (a personal computer), a computer peripheral device, a portable terminal, an information terminal, a portable telephone, a consumer gaming machine, and all other products that handle digital video. The compressing encoding scheme is not limited to the MPEG.