JP4730585B2 - Encoding apparatus and method, decoding apparatus and method, information processing system, recording medium, and program - Google Patents

Description

The present invention relates to an encoding device and method, a decoding device and method, an information processing system, a recording medium, and a program, and in particular, encoding that can suppress unauthorized duplication of content data using an analog signal. The present invention relates to an apparatus and method, a decoding apparatus and method, an information processing system, a recording medium, and a program.

  Conventionally, in recording and transmission of image data, audio data, and the like, processing such as information encoding and decoding is usually performed.

  FIG. 1 shows a configuration example of a conventional image processing system. The image processing system 10 processes an encoded digital image signal Vcd, which is an encoded digital image signal, and outputs an analog image signal Van, and an analog image signal Van output from the playback device 11. A display device 12 for displaying an image and an encoding device 13 for encoding an analog image signal Van output from the playback device 11 and recording the encoded digital image signal Vcd on a recording medium are provided.

  The playback device 11 includes a decoding unit 21 and a D / A (Digital / Analog) conversion unit 22 (hereinafter referred to as D / A 22). The decoding unit 21 decodes an encoded digital image signal Vcd read from a recording medium such as an optical disk (not shown). The D / A 22 converts the decoded digital image signal Vdg into an analog image signal Van.

  The playback device 11 supplies the analog image signal Van to the display device 12 and the encoding device 13.

  The display device 12 has a display 23. The display 23 is configured by, for example, a CRT (Cathode-Ray Tube) display, an LCD (Liquid Crystal Display), or the like. The display device 12 displays the analog image signal Van supplied from the playback device 11 on the display 23.

  The encoding device 13 includes an A / D (Analog / Digital) conversion unit 24 (hereinafter referred to as A / D 24), an encoding unit 25, and a recording unit 26. The A / D 24 converts the analog image signal Van supplied from the playback device 11 into a digital signal, and generates a digital image signal Vdg. The encoding unit 25 encodes the digital image signal Vdg to generate an encoded digital image signal Vcd. The recording unit 26 includes, for example, a hard disk, a semiconductor memory, or a DVD (Digital Versatile Disc) drive, and records the encoded digital image signal Vcd generated by the encoding unit 25 on those recording media.

  That is, the image processing system 10 receives the encoded digital image signal Vcd, reproduces the analog image signal Van from the encoded digital image signal Vcd, displays an image, or regenerates the reproduced analog image signal Van. This is a system for encoding and recording an encoded digital image signal Vcd on a recording medium.

  As described above, since the image processing system 10 generates the analog image signal Van, there is a possibility that the image processing system 10 may be used for unauthorized duplication (illegal copy) using the analog image signal Van.

  That is, since the digital copyright protection function does not operate on the analog image signal Van, the encoding device 13 reproduces the original encoded digital image signal Vcd by digitizing and encoding the analog image signal Van. Can be recorded.

  Conventionally, in order to prevent unauthorized copying using such an analog image signal Van, when copyright protection is provided, the analog image signal Van is scrambled or the analog image signal Van is prohibited from being output. Has been proposed (see, for example, Patent Document 1).

  In addition, by providing a noise information generation unit in one or both of the playback device 11 and the encoding device 13 and embedding noise information in the digital video data that cannot be identified at the time of image playback by one processing, the copy itself is Although it is possible, a digital video apparatus has been proposed in which an image deteriorates remarkably when it is repeated a plurality of times, thereby substantially limiting the number of copies (see, for example, Patent Document 2).

  However, for example, as in Patent Document 1 described above, the reproduction apparatus 11 prevents unauthorized copying by scrambled and outputting the analog image signal Van or prohibiting the output of the analog image signal Van. In the case of this method, there is a problem that the display device 12 cannot display a normal image on the display 23.

  For example, when the playback device 11 scrambles and outputs the analog image signal Van, it is necessary to provide the display device 12 with a function for displaying a normal image corresponding to the scramble function.

  In addition, as in Patent Document 2 described above, in the case where noise information is embedded in a digital image signal by a decoding unit on the reproduction side or an encoding unit on the recording side, a noise information generation unit and a circuit for embedding the noise information are required. There is a problem that the circuit scale increases.

  Therefore, a method for preventing unauthorized copying using an analog image signal without causing inconvenience such as an image not being displayed or an increase in circuit scale has been proposed by the present applicant (for example, (See Patent Document 3).

JP 2001-245270 A Japanese Patent Laid-Open No. 10-289522 Japanese Patent Application Laid-Open No. 2004-289685

  In the method described in Patent Document 3 described above, attention is paid to analog noise such as phase shift of the digital image signal obtained by A / D conversion of the analog image signal, and the code focusing on the analog noise with respect to the digital image signal. By doing so, it is impossible to copy while maintaining good quality without degrading the quality of the image before copying, thereby preventing unauthorized copying using analog image signals, but distributing digital content In recent years, there has been a demand for a proposal of another method for preventing unauthorized copying as described above.

  The present invention has been made in view of such a situation, and makes it possible to suppress unauthorized duplication of content data using an analog signal.

The encoding apparatus according to the present invention includes a predetermined frame in a first block that is a processing target block in a block obtained by dividing a frame image into a plurality of regions of a first frame image that is a processing target frame image of image data . Difference absolute value sum calculating means for calculating a sum of absolute values of differences between specific pixels of a position pixel and specific pixels of a block of a second frame image different from the first frame image; and difference absolute value sum calculating means Detecting means for detecting, as the second block, a block of the second frame in which the sum of the absolute values of the differences calculated by the above is minimized, the first block, and the second block detected by the detecting means Between the difference calculation means for calculating the difference between the pixel values of the pixels other than the specific pixel, the first block, and the second block detected by the detection means. A difference setting means for setting the difference between the predetermined pixels, a difference between pixel values of pixels other than the specific pixel calculated by the difference calculation means, and a difference between pixel values of the specific pixels set by the difference setting means Differential encoding means for encoding each time.

The difference absolute value sum calculating means can set the pixels at the four corners of each block as specific pixels.

May further comprises a search range setting means for setting a search range for searching for a second block in the second frame.

A candidate holding means for holding the minimum value of the sum of absolute values of the differences calculated by the absolute difference value calculating means so far as a candidate for the minimum value, and a sum of absolute values of the differences calculated by the absolute difference value calculating means Comparing means for comparing the value with a candidate for the minimum value held by the candidate holding means, the candidate holding means, based on the comparison result by the comparing means, the absolute value of the difference with the smaller value The sum can be held as a candidate for the minimum value.

May further comprises a block position calculating means for calculating the relative position based on the position of the first block of the second block is detected by the detecting means.

The difference setting means may set the difference of the specific pixel to “0”.

The difference encoding unit orthogonally transforms a difference between pixel values of pixels other than the specific pixel calculated by the difference calculation unit and a difference between pixel values of the specific pixel set by the difference setting unit. Transform means, quantization means for quantizing the coefficient data obtained by orthogonal transformation of the difference by the orthogonal transform means, and variable length code for the quantized coefficient data obtained by quantizing the coefficient data by the quantization means Variable length encoding means for converting to a variable length encoding means.

  The orthogonal transform means may perform discrete sine transform on the difference.

  The block position data, which is the relative position information of the second block with respect to the position of the first block, detected by the detection means, and the encoded data obtained by encoding the difference by the difference encoding means are encoded. It is possible to further include output means for outputting to the outside of the conversion apparatus.

The encoded data obtained by encoding the difference by the difference encoding means is decoded, a decoding means for obtaining a frame image based on the block position data, and a frame image obtained by decoding by the decoding means for the next time Frame image holding means for holding the second block image as a second frame image in detection of the second block, and the difference absolute value sum calculating means uses the frame image held by the frame image holding means as the second frame image. It can be used to calculate the sum of absolute values of differences .

A noise adding means for adding analog noise, which is a noise component for the analog component, to the analog signal image data, and A / D conversion of the analog signal image data to which the analog noise has been added by the noise adding means to obtain digital data A / D conversion means for obtaining the image data of the second difference absolute value sum total calculation means , wherein the difference absolute value summation calculation means converts the frame image of the image data of the digital data obtained by A / D conversion by the A / D conversion means to the second image data . It can be used as a frame image to calculate the sum of absolute values of differences .

The encoding method of the present invention provides a predetermined frame in a first block which is a processing target block in a block obtained by dividing the frame image into a plurality of regions of the first frame image which is a processing target frame image of image data . A difference absolute value sum calculation step for calculating a sum of absolute values of differences between specific pixels of a position pixel and a specific pixel of a block of a second frame image different from the first frame image; and difference absolute value sum calculation A detection step of detecting a second frame block having a minimum sum of absolute values of differences calculated by the processing of the step as a second block , the first block, and the detection of the block. The difference calculation step for calculating the difference between the pixel values of the pixels other than the specific pixel from the second block, the first block, and the detection step are detected. A difference setting step for setting the difference between the pixel values of the specific pixels to a predetermined value and the difference between the pixel values of the pixels other than the specific pixels calculated by the difference calculation step, And a difference encoding step for encoding a difference between pixel values of specific pixels set by the difference setting step for each block.

According to a first recording medium of the present invention, a computer that encodes image data is a processing target in a block of a first frame image that is a processing target frame image of the image data, in which the frame image is divided into a plurality of regions. An absolute difference that calculates the sum of absolute values of differences between specific pixels that are pixels at a predetermined position in the first block that is a block and specific pixels of a second frame image block that is different from the first frame image A value sum calculating means, a detecting means for detecting, as a second block, a block of a second frame in which the sum of the absolute values of the differences calculated by the difference absolute value sum calculating means is minimized, and a first block And a second block detected by the detection means, a difference calculation means for calculating a pixel value difference of pixels other than the specific pixel, a first block, and a detection means detected by the detection means A difference setting unit that sets a difference between pixel values of specific pixels to a predetermined value with the second block, a difference between pixel values of pixels other than the specific pixel calculated by the difference calculation unit, and A program is recorded that functions as a differential encoding unit that encodes a difference between pixel values of specific pixels set by the difference setting unit for each block.

A first program of the present invention is a processing target block in a block obtained by dividing a frame image into a plurality of regions of a first frame image that is a processing target frame image of image data by a computer that encodes image data. The difference absolute value for calculating the sum of the absolute values of the differences between the specific pixel that is a pixel at a predetermined position in the first block and the specific pixel of the block of the second frame image different from the first frame image A sum calculating means, a detecting means for detecting a block of the second frame in which the sum of absolute values of differences calculated by the difference absolute value sum calculating means is a minimum as a second block, and a first block; The difference calculation means for calculating the difference between the pixel values of the pixels other than the specific pixel from the second block detected by the detection means, the first block, and the detection means. A difference setting unit that sets a difference between pixel values of specific pixels to a predetermined value with the second block, a difference between pixel values of pixels other than the specific pixel calculated by the difference calculation unit, and It is made to function as a difference encoding means for encoding the difference between the pixel values of the specific pixels set by the difference setting means for each block.

The decoding device according to the present invention blocks a first frame image, which is a processing target frame image of image data, with a first block, which is a processing target block among blocks obtained by dividing the frame image into a plurality of regions. Of the second block, which is a block of the second frame image different from the first frame image, in which the sum of the absolute values of the pixel value differences in the specific pixel that is a pixel at a predetermined position is the smallest. Based on block position data that is relative position information with respect to one block, extraction means for extracting the second block from the second frame image , and each pixel of the first block and each pixel of the second block each pixel difference of the pixel value by decoding the coded data, the coded data obtained by decoding by differential decoding means and, differential decoding means for obtaining a difference between the pixel value of each pixel From the difference between the pixel values, determining means for determining the difference between the pixel values of a particular pixel, a difference setting means for setting a difference between the pixel values of a particular pixel is determined by the determining means to a predetermined value, the difference setting means difference in pixel values for a particular pixel the predetermined value is set by, and the difference of the pixel values of the pixels other than the specific pixel that has not been discriminated by the discriminating means, the pixel values of the second blocks extracted by the extraction means And pixel value adding means for obtaining the first block.

The specific pixels may be pixels at the four corners of the block .

The difference decoding means includes variable length decoding means for variable length decoding the coded data, the inverse quantization means for inversely quantizing the quantized coefficient data encoded data obtained by the variable length decoding by the variable length decoding unit And inverse orthogonal transform means for performing inverse orthogonal transform on the coefficient data obtained by inverse quantization of the quantized coefficient data by the inverse quantization means.

  The orthogonal transform means may perform inverse discrete sine transform on the coefficient data.

The difference setting means may be a difference between the specific pixel is set to "0".

The image processing apparatus may further include order alignment means for rearranging the pixel values of each pixel obtained as a result of addition by the pixel value addition means for each block in raster order.

  The image processing apparatus may further include an output unit that holds the first block obtained by the addition by the pixel value addition unit and outputs the first block to the outside of the decoding device in units of frame images.

  The image processing apparatus further includes frame image holding means for holding the frame image output by the output means as a second frame image in the next extraction of the second block, and the extraction means holds the frame held by the frame image holding means. The image can be used as the second frame image, and the second block can be extracted based on the block position data.

The digital image data obtained by the pixel value addition means is D / A converted and converted into an analog signal, and the digital image data is obtained by D / A conversion by the D / A conversion means. Noise adding means for adding analog noise, which is a noise component for the analog component, to the analog signal is further provided, and the decoding device may output an analog signal to which analog noise is added by the noise adding means. it can.

According to the decoding method of the present invention, a block between a first frame image that is a processing target frame image of image data and a first block that is a processing target block among blocks obtained by dividing the frame image into a plurality of regions. Of the second block, which is a block of the second frame image different from the first frame image, in which the sum of the absolute values of the pixel value differences in the specific pixel that is a pixel at a predetermined position is the smallest. An extraction step of extracting the second block from the second frame image based on block position data which is relative position information with respect to one block, and each pixel of the first block and each pixel of the second block decodes the encoded data which the difference is encoded pixel values, a difference decoding step of obtaining a difference between the pixel values of the pixels, the encoded data is decoded by the processing of the differential decoding step Setting from the difference between the pixel value of each pixel obtained, a determination step of determining the difference between the pixel values of a particular pixel, the difference between the pixel values of a particular pixel is determined by the processing determination step to a predetermined value Te a difference setting step of, in the pixel value of the particular pixel the predetermined value is set by the processing of the difference setting step difference, and the difference of the pixel values of the pixels other than the specific pixel that has not been determined by the processing determination step, A pixel value adding step of adding the pixel value of the second block extracted by the process of the extracting step for each pixel to obtain the first block.

According to a second recording medium of the present invention, a processing target block in a block obtained by dividing a frame image into a plurality of areas of a first frame image that is a processing target frame image of the image data by a computer that decodes the image data. A second frame image different from the first frame image, in which the sum of absolute values of differences in pixel values at a specific pixel that is a pixel at a predetermined position in the block is minimized. the second block is a block based on the block position data is relative position information for the first block, and extracting means for extracting a second block from the second frame image, each of the first block decodes the encoded data which the difference is coded in pixel values between each pixel of pixel and the second block, the differential decoding means for obtaining a difference between the pixel value of each pixel, the difference decoding means Ri from the difference of the pixel values of pixels coded data obtained by decoding, and determining means for determining the difference between the pixel values of a particular pixel, the difference between the pixel values of a particular pixel is determined by the determining means a difference setting means for setting a predetermined value, the pixel value of the particular pixel the predetermined value is set by the difference setting unit difference, and the difference of the pixel values of the pixels other than the specific pixel that has not been judged by the judgment means A program is recorded that adds the pixel value of the second block extracted by the extraction means for each pixel to function as pixel value addition means for obtaining the first block.

According to a second program of the present invention, a computer that decodes image data is a processing target block in a block obtained by dividing a frame image into a plurality of regions of a first frame image that is a processing target frame image of the image data. A second frame image different from the first frame image that minimizes the sum of absolute values of differences in pixel values at a specific pixel that is a pixel at a predetermined position in the block with a certain first block. Extraction means for extracting the second block from the second frame image based on block position data, which is relative position information of the second block, which is a block, with respect to the first block, and each pixel of the first block When the difference in pixel values between each pixel of the second block decodes the encoded data, a difference decoding means for obtaining a difference between the pixel value of each pixel, differential decoding means From the difference between the pixel value of each pixel obtained are more coded data decoding, and determining means for determining the difference between the pixel values of a particular pixel, the difference between the pixel values of a particular pixel is determined by the determining means a difference setting means for setting a predetermined value, the pixel value of the particular pixel the predetermined value is set by the difference setting unit difference, and the difference of the pixel values of the pixels other than the specific pixel that has not been judged by the judgment means The pixel value is added to the pixel value of the second block extracted by the extraction unit for each pixel to function as a pixel value addition unit for obtaining the first block.

The first information processing system of the present invention is an information processing system that includes an encoding unit and a decoding unit, and image data deteriorates when encoding processing and decoding processing are repeated on the image data. The encoding unit includes a pixel at a predetermined position in the first block that is the processing target block in the block obtained by dividing the frame image into a plurality of regions of the first frame image that is the processing target frame image of the image data. a specific pixel is a sum of absolute differences calculation means for calculating the sum of absolute values of differences between a particular pixel in the block of the second frame image different from the first frame image, calculated by the difference absolute value sum calculating means and a detection unit value of the sum of absolute values to detect a block of the second frame as a minimum as a second block of the difference, the first block, a second detected by the detection means The pixel value of the specific pixel between the difference calculation means for calculating the difference between the pixel values of the pixels other than the specific pixel with the lock, the first block, and the second block detected by the detection means A difference setting means for setting the difference between the predetermined pixels, a difference between pixel values of pixels other than the specific pixel calculated by the difference calculation means, and a difference between pixel values of the specific pixels set by the difference setting means And differential encoding means for encoding each time.

A second information processing system of the present invention is an information processing system that includes an encoding unit and a decoding unit, and the image data deteriorates when the encoding process and the decoding process are repeated on the image data. The decoding unit is configured to determine a predetermined number in the block between the first frame image that is the processing target frame image of the image data and the first block that is the processing target block among the blocks obtained by dividing the frame image into a plurality of regions. The first block of the second block, which is a block of the second frame image different from the first frame image, in which the sum of the absolute values of the pixel value differences in the specific pixel that is the pixel at the position is minimized. based on the block position data is relative position information with respect to an extraction means for extracting a second block from the second frame image, for each pixel and the second blocks of the first block Decodes the encoded data in which the difference of the pixel values are encoded in the pixel, a difference decoding means for obtaining a difference between the pixel value of each pixel, each pixel encoded data obtained by decoding by differential decoding means from the difference between the pixel values, determining means for determining the difference between the pixel values of a particular pixel, a difference setting means for setting a difference between the pixel values of a particular pixel is determined by the determining means to a predetermined value, the difference setting means difference in pixel values for a particular pixel the predetermined value is set by, and the difference of the pixel values of the pixels other than the specific pixel that has not been discriminated by the discriminating means, the pixel values of the second blocks extracted by the extraction means And a pixel value adding means for obtaining the first block by adding for each pixel.

In the encoding apparatus and method, the first recording medium, and the first program of the present invention, the block of the first frame image that is the frame image to be processed of the image data is divided into a plurality of regions. Calculates the sum of absolute values of the difference between the specific pixel that is a pixel at a predetermined position in the first block that is the processing target block and the specific pixel of the block of the second frame image that is different from the first frame image Then, the block of the second frame that minimizes the sum of the absolute values of the calculated differences is detected as the second block, and between the first block and the detected second block The difference between the pixel values of the pixels other than the specific pixel is calculated, and the difference between the pixel values of the specific pixel is set to a predetermined value between the first block and the detected second block. Special Difference in pixel values of pixels other than the pixels, and the difference between the pixel value of a specific pixel set by the difference setting means is encoded for each block.

In the decoding apparatus and method, the second recording medium, and the second program according to the present invention, the first frame image that is the processing target frame image of the image data is a block obtained by dividing the frame image into a plurality of regions. Different from the first frame image, in which the sum of the absolute values of the pixel value differences in the specific pixel that is a pixel at a predetermined position in the block is the smallest among the first block that is the processing target block A second block is extracted from the second frame image based on block position data that is relative position information of the second block, which is a block of the second frame image, to the first block ; difference in pixel values between each pixel of each pixel and the second block of the block is the difference between the coded data is decoded pixel value of each pixel is obtained, the encoded data From the difference between the pixel values of pixels obtained by decoding the difference between the pixel value of a particular pixel is determined, and the difference of the determined pixel value of a specific pixel is set to a predetermined value, a predetermined value difference of the set pixel value of a particular pixel, and the difference of the pixel values of the pixels other than the specific pixel that has not been discriminated, are added for each pixel on the pixel values of those of the second block, the first block can get.

In the first information processing system of the present invention, the encoding unit uses a processing target block in a block obtained by dividing the frame image into a plurality of regions of the first frame image that is the processing target frame image of the image data. The sum of absolute values of differences between specific pixels that are pixels at a predetermined position in a certain first block and specific pixels in a block of a second frame image different from the first frame image is calculated, and the calculated A block of the second frame in which the sum of absolute values of the differences is minimized is detected as the second block, and pixels other than the specific pixel are detected between the first block and the detected second block. The pixel value difference between the first block and the second block is set to a predetermined value between the first block and the second block, and the calculated pixel values of the pixels other than the specific pixel Difference Beauty, the difference between the pixel value of a specific pixel is set is encoded for each block.

In the second information processing system of the present invention, the decoding unit is a processing target block in a block obtained by dividing the frame image into a plurality of regions of the first frame image that is the processing target frame image of the image data. A block of a second frame image different from the first frame image, in which the sum of absolute values of differences in pixel values at a specific pixel that is a pixel at a predetermined position in the block with the first block is minimized. A second block is extracted from the second frame image based on block position data that is relative position information of the second block to the first block, and each pixel of the first block each difference in pixel values between each pixel of the second block is a difference is obtained in the coded data is decoded pixel value of each pixel, encoded data obtained by decoding From the difference between the pixel value of, the determination is the difference between the pixel value of a particular pixel, the difference of the determined pixel value of a specific pixel is set to a predetermined value, the pixel of the particular pixel the predetermined value is set The difference between the values and the difference between the pixel values of the pixels other than the specific pixels that have not been determined are added to the pixel value of the second block for each pixel to obtain the first block.

  According to the present invention, unauthorized duplication of content data using an analog signal can be suppressed. In particular, without causing inconveniences such as no image being displayed or an increase in circuit scale, the second and subsequent encoding and decoding processes significantly degrade image data and suppress unauthorized copying using analog signals. can do.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 2 is a diagram illustrating a configuration example of an image processing system to which the present invention is applied.

  An image processing system 30 shown in FIG. 2 includes a playback device 31, a display device 32, and an encoding device 33, processes an encoded digital image signal to generate an analog image signal, and generates the image. Or the analog image signal is encoded again and the encoded digital image signal is recorded on a recording medium.

  The playback device 31 includes a decoding unit 41 and a D / A (Digital / Analog) conversion unit 42 (hereinafter referred to as D / A 42). The decoding unit 41 decodes the encoded digital image signal Vcd0 reproduced from a recording medium such as an optical disk (not shown) to generate a digital image signal Vdg0. Details of the decoding unit 41 will be described later. The D / A 42 converts the digital image signal Vdg0 into an analog signal, and generates an analog image signal Van1. The playback device 31 supplies the analog image signal Van1 to the display device 32 and the encoding device 33.

  This analog image signal Van1 is accompanied by analog distortion. The analog distortion includes, for example, distortion caused by removing a high frequency component when converted to an analog signal by the D / A 42, and distortion caused by a phase shift of the signal when converted to an analog signal by the D / A 42. Etc. are included. As a method for evaluating the image degradation due to the analog distortion, for example, there are S / N (Signal-to-Noise) evaluation, visual evaluation (evaluation of visual deterioration), and the like. This analog distortion may be naturally occurring that usually occurs in an actual apparatus, or may be intentionally generated as described later.

  The display device 32 includes a display 43 such as a CRT (Cathode Ray Tube) display, LCD (Liquid Crystal Display), or the like. When the analog image signal Van1 output from the playback device 31 is acquired, the image is displayed on the display 43. To display.

  The encoding device 33 includes an A / D (Analog / Digital) conversion unit 44 (hereinafter referred to as A / D 44), an encoding unit 45, a recording unit 46, a decoding unit 41, a D / A 42, and a display 43. ing. The encoding device 33 converts the analog image signal Van1 supplied from the playback device 31 in the A / D 44 into a digital image signal Vdg1, then encodes it in the encoding unit 45, and encodes the encoded digital image in the recording unit 46. The signal Vcd1 is recorded on the recording medium. Further, when the encoding device 33 re-decodes the encoded digital image signal Vcd1 in the decoding unit 41 and D / A converts the decoded digital image signal Vdg2 in the D / A 42 to generate the analog image signal Van2, the image Is displayed on the display 43.

  The A / D 44 converts the analog image signal Van1 output from the playback device 31 into a digital signal, and generates a digital image signal Vdg1. The encoding unit 45 encodes the digital image signal Vdg1 to generate an encoded digital image signal Vcd1. Details of the encoding unit 45 will be described later. The recording unit 46 includes, for example, a hard disk, a semiconductor memory, or a DVD (Digital Versatile Disc) drive, and records the encoded digital image signal Vcd1 generated by the encoding unit 45 on those recording media.

  The decoding unit 41 of the encoding device 33 decodes the encoded digital image signal Vcd1 generated by the encoding unit 45, and generates a digital image signal Vdg2. The D / A 42 of the encoding device 33 converts the digital image signal Vdg2 decoded by the decoding unit 41 of the encoding device 33 into an analog image signal Van2. The display 43 of the encoding device 33 displays the image of the analog image signal Van2.

  Although details will be described later, the encoding unit 45 of the encoding device 33 uses the analog distortion included in the analog image signal Van1 to significantly improve the quality (image quality) of the image signal content. Degrade and encode. In addition, the decoding unit 41 of the reproduction device 31 and the encoding device 33 also decodes the encoded digital image signal input by the decoding method corresponding to the encoding unit 45.

  That is, in FIG. 2, identification numbers are assigned to the analog image signal Van, the digital image signal Vdg, and the encoded digital image signal Vcd depending on the position of each signal. This indicates that the signal is different from other similar signals. For example, in the case of the analog image signal Van, the analog image signal Van2 output from the D / A 42 of the encoding device 33 is encoded using the analog distortion while degrading the image quality, and the encoding unit 45. Is a signal of image information that is generated by using a signal after passing through the decoding unit 46 corresponding to the above and deteriorated from the analog image signal Van1 output from the D / A 42 of the reproducing device 31. Similarly, the image of the digital image signal Vdg2 is also deteriorated from the image of the digital image signal Vdg1, and the image of the digital image signal Vdg1 is also deteriorated from the image of the digital image signal Vdg0. The same applies to the encoded digital image signal Vcd, and the image of the encoded digital image signal Vcd1 is more deteriorated than the encoded digital image signal Vcd0.

  As described above, in the image processing system 30, the playback device 31 outputs the analog image signal Van1, and the display device 32 displays the image. The encoding device 33 uses the analog image signal Van1 to copy the image data. In this case, since the image is deteriorated, duplication using the analog image signal Van can be suppressed.

  Next, the detail of each part is demonstrated. First, the encoding unit 45 of the encoding device 33 will be described. FIG. 3 is a block diagram illustrating a detailed configuration example of the encoding unit 45 of FIG. The encoding unit 45 includes a blocking unit 61, a four-corner matching block detection unit 62, a residual calculation unit 63, a residual encoding unit 64, an output unit 65, a local decoding unit 66, and a frame memory 67. .

  The blocking unit 61 divides the frame image data included in the input digital image signal Vdg1 into blocks of a predetermined size. The blocking unit 61 divides the frame image data (the image signal of the effective screen) into blocks (BL) having a size of 8 pixels × 8 pixels, for example, as shown in FIG. In FIG. 4, white circles indicate pixel data constituting the blocks, and the horizontal and vertical straight lines indicate that part of the frame image data is 3 blocks in the horizontal direction and 2 blocks in the vertical direction (BL71 to BL76). (Total 6 blocks). FIG. 4 is a schematic diagram showing how the frame image data is blocked, and does not show the actual contents of the frame image data. The blocking unit 61 in FIG. 3 supplies the image data thus blocked to the four-corner matching block detection unit 62 and the residual calculation unit 64 for each block.

  The four-corner coincidence block detection unit 62 stores the previous frame (one frame before the processing target frame) stored in the frame memory 67 with respect to the block (BL) divided in the current frame (processing target frame). Blocks having the same pixel values at the four corners are detected from the image data. That is, as will be described later, the four-corner matching block detection unit 62 sets a predetermined search range in the previous frame for the reference block (processing target block) of the current frame, and within the search range, the reference block A block (four-corner matching block) in which the sum of the absolute differences from the four corner pixels is the smallest is detected.

  For example, assuming that the reference block is BL71 in FIG. 4, the four-corner coincidence block detecting unit 62 pays attention to the pixels 71A to 71D at the four corners of BL71 as shown in FIG. When the search range is set, the same 8 pixel × 8 pixel block (target block) as BL 71 is arbitrarily set within the search range. Then, the four corner coincidence block detection unit 62 includes the four corner pixels of the target block set in the previous frame and the four corner pixels (pixels 71A to 71D) of the reference block (BL71) of the current frame described above. Then, the difference value of the pixel value is taken for each corresponding pixel, and the block of the previous frame that minimizes the sum of the difference values is searched.

  FIG. 5 is a schematic diagram showing the pixels at the four corners of the reference block, and does not show the actual contents of the image data. In the above description, the previous frame is described as being the frame immediately before the current frame. However, the present invention is not limited to this, and any frame may be used as long as it is different from the current frame. It may be two or more frames before the current frame. The relationship between the current frame and the previous frame is the same in the following.

  FIG. 6 is a block diagram illustrating a detailed configuration example of the four-corner block detection unit 62. In FIG. 6, a four-corner block detection unit 62 includes a pixel value acquisition unit 81, a search range setting unit 82, a target block setting unit 83, a difference absolute value sum calculation unit 84, a comparison unit 85, a minimum value candidate holding unit 86, and four corners. It has a matching block candidate holding unit 87, a search control unit 88, and a block position data calculation unit 89.

  The pixel value acquisition unit 81 determines the pixel values at the four corners of the processing target block (reference block) from the pixel value supplied for each block from the blocking unit 61 (FIG. 3) and information on the pixel (in the case of FIG. 5, Pixel 71A to pixel 71D) are acquired. Such information is supplied to the search range setting unit 82. The search range setting unit 82 acquires in advance information (pixel value, etc.) regarding the previous frame (the frame immediately before the current frame to be processed) from the frame memory 67 (FIG. 3). Thus, a search range for searching for blocks having pixel values at four corners that match (or approximate) the pixel values at the four corners of the reference block (pixel values at the four corners supplied from the pixel value acquisition unit 81) is set.

  FIG. 7 is a schematic diagram showing how the search range is set. For example, as shown in FIG. 7A, in the current frame 91 that is the current processing target frame, when the pixel value acquisition unit 81 supplies information including the pixel values of the four corners of the reference block BL92, As shown in FIG. 7B, the search range setting unit 82 sets a search range for the previous frame 93 that is the frame immediately before the current frame. At this time, the search range setting unit 82 sets the search range 95 in the previous frame 93 with reference to the BL 94 that is a block at the same position as the position of the BL 92 in the current frame 91. For example, the search range setting unit 82 sets an area (area surrounded by a dotted line in FIG. 7B) that is expanded by 8 pixels in the horizontal direction and 8 pixels in the vertical direction centering on BL94.

  When the search range 95 is set, the search range setting unit 82 supplies information regarding the search range 95 and information regarding the reference block to the target block setting unit 83. The target block setting unit 83 sets a target block for comparing the pixel values at the four corners with the reference block within the search range 95 of the previous frame 93. At this time, the block-of-interest setting unit 83 sets all the blocks established within the search range 95 as processing targets, and sets the blocks of interest one by one from among them. The target block selection method (selection order) is arbitrary, but as will be described later, the target block setting unit 83 finally sets the pixel values at the four corners of all the blocks to the pixel values at the four corners of the reference block. This setting process is repeated so as to make a comparison.

  When one target block is set, the target block setting unit 83 supplies information regarding the target block and information regarding the reference block to the difference absolute value sum calculating unit 84. The difference value absolute value sum calculating unit 84 corresponds to the pixel values at the four corners of the target block of the previous frame 93 set by the target block setting unit 83 and the pixel values at the four corners of the reference block of the current frame 91, respectively. A difference value is obtained for each pixel to be calculated, and a sum of absolute values of the difference values is calculated.

  That is, for example, the pixel value at the upper left corner of the reference block is A, the pixel value at the upper right corner is B, the pixel value at the lower left corner is C, and the pixel value at the lower right corner is D. The pixel value at the upper left corner of the block of interest is A ′, the pixel value at the upper right corner is B ′, the pixel value at the lower left corner is C ′, and the pixel value at the lower right corner is D ′. At this time, the sum Z of the absolute values of the difference values calculated by the difference value absolute value sum calculation unit 84 is calculated as in the following equation (1).

  Z = | A−A ′ | + | B−B ′ | + | C−C ′ | + | D−D ′ | (1)

  The difference absolute value sum calculation unit 84 supplies the calculation result (sum of absolute values of difference values Z) and information regarding the reference block and the target block to the comparison unit 85. The comparison unit 85 stores the value (current calculation result) supplied from the difference value absolute value total calculation unit 84 in the minimum value candidate holding unit 86 of the sum Z of the absolute values of the difference values at the current stage. Compare with the minimum value. Then, the comparison unit 85 causes the minimum value candidate holding unit 86 to hold the smaller one of them as the current minimum value, and the attention block corresponding to the minimum value of the four corner matching block (search target block). Information regarding the block of interest is supplied to the four-corner matching block candidate holding unit 87 to be held.

  The minimum value candidate holding unit 86 includes a storage medium such as a semiconductor memory, and holds the minimum value of the sum Z of absolute values of the difference values supplied from the comparison unit 85. Then, the minimum value candidate holding unit 86 supplies the held minimum value to the comparison unit 85 based on a request from the comparison unit 85.

  The four-corner matching block candidate holding unit 87 includes a storage medium such as a semiconductor memory, for example, and information regarding the block corresponding to the minimum value held in the minimum value candidate holding unit 86 is a candidate for a four-corner matching block. Held as. The four-corner matching block is a search target block, and the sum of the difference values between the pixel values at the four corners and the pixel values at the four corners of the reference block is minimized (the pixel values at the four corners match) Is the most approximate)) block. Finally, the four-corner matching block candidates held in the four-corner matching block candidate holding unit 87 are set as the four-corner matching blocks.

  When the comparison process ends, the comparison unit 85 supplies the fact to the search control unit 88. The search control unit 88 determines whether or not the processing has been completed for all the blocks in the search range 95, and if the search control unit 88 determines that there is an unprocessed block, A new attention block is set.

  When it is determined that all the blocks have been processed within the search range 95, the search control unit 88 supplies the fact to the block position data calculation unit 89.

  That is, the block-of-interest setting unit 83 sets one block of interest one by one within the search range 95 of the previous frame 93, and the difference absolute value sum calculation unit 84 sets the pixels at the four corners in the set block of interest and the reference block. The sum Z of absolute values of the difference values of the values is calculated, and the comparison unit 85 compares the sum Z of the absolute values of the calculated difference values with the minimum value. If the current calculation result is smaller, the minimum value is calculated. Update. Under the control of the search control unit 88, the above processing is repeated for all the blocks that can be the target block in the search range 95, and the four corner matching block that is the final minimum value block is determined.

  When the block position data calculation unit 89 obtains information about the four corner matching block candidates at that time as the four corner matching block information from the four corner matching block candidate holding unit 87, the four corner matching block is based on the information. Block position data, which is vector information (that is, a motion vector) indicating a positional deviation between the reference block and the reference block, is calculated.

  FIG. 8 is a schematic diagram showing how block position data is calculated. When BL92 is set as a reference block for the current frame 91 as shown in FIG. 8A, as shown in FIG. 8B, the search range centered on BL94 at the same position as BL92 as shown in FIG. 8B. 95 is set, and within the search range 95, a four-corner coincidence block (a block where the pixel values at the four corners are closest to the reference block) 96 is searched. The block position data calculation unit 89 is a block which is a motion vector indicating how much the four-corner matching block 96 searched in this way has moved from the reference block BL92 (BL94 at the same position as the BL92). The position data 97 (Vcdp) is calculated.

  The block position data calculation unit 89 (four corner matching block detection unit 62) supplies the calculated block position data Vcdp to the output unit 65 and the residual calculation unit 63.

  Returning to FIG. 3, the residual calculation unit 63 extracts the four-corner matching block 96 from the image data of the previous frame 93 and the block position data Vcdp stored in the frame memory 67, and the target block (BL 92) of the current frame 91. And the difference value (residual) between each pixel is calculated. At this time, the residual calculation unit 63 forcibly outputs the residuals at the four corners of the block as “0” in order to improve the efficiency of the encoding process in the residual encoding unit 64.

  FIG. 9 is a block diagram illustrating a detailed configuration example of the residual calculation unit 63. In FIG. 9, the residual calculation unit 63 includes a block extraction unit 101, a pixel determination unit 102, a difference value calculation unit 103, a difference value setting unit 104, and a residual output unit 105.

  When the block extraction unit 101 acquires the image data of the previous frame from the frame memory 67, the block extraction unit 101 extracts the four corner matching block 96 based on the block position data Vcdp supplied from the four corner matching block detection unit 62, and The image data of the matching block 96 (four corner matching block image data) is supplied to the pixel determination unit 102. That is, the block extraction unit 101 identifies the position of the four corner coincidence block from the position of the reference block based on the block position data Vcdp, extracts the image data at that position from the image data of the previous frame, and performs pixel determination To the unit 102.

  When the pixel determination unit 102 acquires the four-corner matching block image data and the block image data of the current frame (reference block image data), the pixels for which the residual is calculated based on them are the pixels at the four corners of the block. It is determined whether or not. If it is determined that the pixel is at the four corners, the pixel determination unit 102 supplies the fact to the difference value setting unit 104. If it is determined that the pixel is a pixel other than the pixels at the four corners, the pixel determination unit 102 supplies the pixel value of the four corner matching block image data and the pixel value of the image data of the reference block to the difference value calculation unit 103.

  The difference value calculation unit 103 calculates the difference between the pixel value of the four-corner matching block image data supplied from the pixel determination unit 102 and the pixel value of the image data of the reference block, and supplies the difference value to the residual output unit 105. To do.

  The difference value setting unit 104 sets the difference value to “0” for the four corner pixels of the four-corner matching block image data and the reference block image data, and supplies the difference value to the residual output unit 105.

  The residual output unit 105 supplies the difference value supplied from the difference value calculation unit 103 and the difference value setting unit 104 to the residual encoding unit 64 (FIG. 3) as a residual in block units.

  Returning to FIG. 3, the residual encoding unit 64 encodes the residual calculated by the residual calculation unit 63 and supplies the encoded result to the output unit 65 as encoded data Vcdq.

  FIG. 10 is a block diagram illustrating a detailed configuration example of the residual encoding unit 64. In FIG. 10, the residual encoding unit 64 includes a DST (Discrete Sine Transform) converting unit 121, a quantizing unit 122, and a Huffman encoding 123.

  The DST conversion unit 121 encodes the residual supplied from the residual calculation unit 114 for each block. The DST transform expresses a waveform by superimposing orthogonal sine waves, and is a kind of orthogonal transform. For example, the DST conversion unit 121 performs DST conversion on a certain pixel column or row as shown in FIG. 11A, thereby converting the pixel value function into a waveform in which sine waves as shown in FIG. 11B are superimposed. Express.

  That is, if the pixel position shown in FIG. 11A is i, the base number shown in FIG. 11B is j, and the number of orthogonal transformation target pixels shown in FIG. Is expressed as a superposition of sine waves represented by the following formula (2).

  FIG. 11 shows an example of DST conversion in a one-dimensional case for explanation, but the DST conversion unit 121 actually performs two-dimensional DST conversion on each block of the residual.

When performing DST conversion in two dimensions, the DST conversion unit 121 performs one-dimensional DST conversion in each of the horizontal direction and the vertical direction, as shown in FIG. That is, the horizontal pixel position (FIG. 12) is i, the horizontal base number is j, the vertical pixel position (FIG. 12) is k, the vertical base number is l (el), and the number of pixels in the horizontal direction It was a N _h, when the number of pixels in the vertical direction and N _v, DST conversion unit 121 are expressed as a superposition of sine waves shown the function of the pixel values in equation (3) below.

  Since the values of the residuals at the four corners are “0” (because the residual calculation unit 63 sets so), the values concentrated in the low frequency in the data converted by DST. Accordingly, the DST conversion unit 121 can perform orthogonal transformation more efficiently than orthogonal transformation by DCT (Discrete Cosine Transform), for example.

  Returning to FIG. 10, the DST conversion unit 121 supplies the converted data to the quantization unit 122. The quantization unit 122 quantizes the coefficient data DST-transformed by the DST transform unit 121 using a quantization table as in the case of encoding using general orthogonal transform such as DCT. The quantization unit 122 supplies the quantized coefficient data obtained by the quantization to the Huffman coding unit 123. The Huffman encoder 123 encodes the quantized coefficient data of each block supplied from the quantizer 122 by Huffman encoding, and outputs the Huffman encoded data as encoded data Vcdq to the output unit 65 (FIG. 3). To supply.

  Returning to FIG. 3, the output unit 65 encodes the block position data Vcdp supplied from the four-corner matching block detection unit 62 and the encoded data Vcdq supplied from the residual encoding unit 64 into the encoded digital image signal Vcd. Are supplied to the recording unit 46 and the decoding unit 41 (both in FIG. 2).

  The output unit 65 also supplies the encoded digital image signal Vcd to the local decoding unit 66.

  The local decoding unit 66 generates a frame to be a reference destination of the block position data Vcdp (motion vector) when the processing of the encoding unit 45 moves to the next frame of the current processing target frame (next next). The encoded digital image signal Vcd output from the output unit 65 is decoded in order to generate image data used as a previous frame in the processing for the frame.

  FIG. 13 is a block diagram illustrating a detailed configuration example of the local decoding unit 66. In FIG. 13, the local decoding unit 66 includes a data decomposing unit 141, a four corner matching block extracting unit 142, a residual decoding unit 143, a pixel value adding unit 144, and a block decomposing unit 145.

  When the data decomposing unit 141 obtains the encoded digital image signal Vcd input to the local decoding unit 66, the data decomposing unit 141 separates the encoded digital image signal Vcdp into the block position data Vcdp and the encoded data Vcdq. 142, and the encoded data Vcdq is supplied to the residual decoding unit 143.

  When the four-corner matching block extraction unit 142 acquires the image data of the previous frame (the previous frame image data) and acquires the block position data Vcdp, the encoding unit 45 converts the previous frame image data into the encoding unit 45 based on the block position data Vcdp. Image data of the searched four corner coincidence block is extracted. The four corner matching block extraction unit 142 supplies the extracted image data of the four corner matching block to the pixel value addition unit 144.

  The residual decoding unit 143 decodes the encoded data Vcdq supplied from the data decomposing unit 141, and obtains a residual of the reference block (difference between pixel values of the reference block and the four corner matching blocks).

  FIG. 14 is a block diagram illustrating a detailed configuration example of the residual decoding unit 143 of FIG.

  14, the residual decoding unit 143 includes a Huffman decoding unit 161, an inverse quantization unit 162, and an IDST (Inverse Discrete Sine Transform) conversion unit 163.

  When the Huffman decoding unit 161 acquires the encoded data Vcdq supplied from the data decomposing unit 141 (FIG. 13), the Huffman decoding unit 161 converts the encoded data Vcdq to the Huffman encoding unit 123 (FIG. 10) of the residual encoding unit 64. When decoding is performed by a decoding method corresponding to the Huffman encoding method and quantized coefficient data is obtained, the quantized coefficient data is supplied to the inverse quantization unit 162.

  The inverse quantization unit 162 has a quantization table (none of which is shown) similar to the quantization table of the quantization unit 122 (FIG. 10) of the residual encoding unit 64, and is supplied from the Huffman decoding unit 161. The quantized coefficient data is inversely quantized using the quantization table, and coefficient data of each block, which is DST-converted pixel value data, is obtained. The inverse quantization unit 162 supplies the coefficient data to the IDST conversion unit 163.

  When the IDST conversion unit 163 acquires the coefficient data supplied from the inverse quantization unit 162, the DST conversion process by the DST conversion unit 121 (FIG. 10) of the residual encoding unit 64 is performed on the coefficient data for each block. Inverse DST conversion processing is performed by a method corresponding to the above to obtain pixel data of each block. The IDST conversion unit 163 supplies the pixel data (residual) to the pixel value addition unit 155 (FIG. 13).

  Returning to FIG. 12, the residual decoding unit 154 calculates the residual from the encoded data Vcddiff in this way, and supplies the obtained residual to the pixel value adding unit 155.

  The pixel value adding unit 144 adds the image data of the four corner matching block supplied from the four corner matching block extracting unit 142 to the residual supplied from the residual decoding unit 143. That is, the pixel value adding unit 144 obtains the pixel value of each pixel of the reference block of the current frame by this addition process.

  FIG. 15 is a block diagram illustrating a detailed configuration example of the pixel value addition unit 144 of FIG.

  In FIG. 15, the pixel value addition unit 144 includes a pixel determination unit 181, a residual setting unit 182, an addition value calculation unit 183, and an order alignment unit 184.

  Based on the residual supplied from the residual decoding unit 143, the pixel determination unit 181 determines whether the pixel to be processed (the pixel to which the pixel value is added from now on) is the pixel at the four corners of the block (specific pixel). Determine whether. When the pixel determination unit 181 determines that the pixel to be processed is the four corner pixels (specific pixels) of the block, the pixel determination unit 181 supplies the determination result to the residual setting unit 182, and the pixel to be processed is the four corners of the block. When it is determined that the pixel is not a specific pixel (specific pixel), the residual is supplied to the added value calculation unit 183.

  When the residual setting unit 182 obtains a determination result that the pixel to be processed is a pixel at the four corners of the block (specific pixel) from the pixel determination unit 181, in order to avoid deterioration due to digital multi-encoding / decoding, The residual of the pixel is set to a predetermined value (for example, “0”), and the residual is supplied to the addition value calculation unit 183.

  The addition value calculation unit 183 adds the pixel values of the four corner matching blocks to the residual supplied from the pixel determination unit 181 or the residual setting unit 182, and supplies the addition result to the order alignment unit 184.

  The order arrangement unit 184 rearranges the order of the pixel values supplied from the addition value calculation unit 183 in the order of raster scanning. Then, each pixel value (image data) in which the order is rearranged is supplied to the block decomposing unit 145 (FIG. 13).

  As described above, the pixel value addition unit 144 sets the residual value to “0” for the pixels at the four corners (specific pixels) of the block, and directly uses the pixel values of the four corner matching block image data as the addition result. By doing so, the pixel value adding unit 144 can suppress encoding distortion and suppress deterioration due to digital multi-encoding / decoding.

  Returning to FIG. 12, the block decomposing unit 145 accumulates the image data for each block supplied from the pixel value adding unit 144, generates frame image data, and uses it as image data (digital image signal Vdg) of the previous frame. The data is output to the frame memory 67 (FIG. 3).

  In FIG. 3, the frame memory 67 holds the image data (digital image signal) decoded by the local decoding unit 66. At this time, the frame memory 67 discards the image data held so far and holds the image data newly supplied from the local decoding unit 66. Then, the frame memory 67 supplies the held image data as the image data of the previous frame to the four-corner matching block detection unit 62, the residual calculation unit 63, and the local decoding unit 66 as necessary.

  That is, the frame memory 67 is rewritten when the frame of interest which is the current processing target by the encoding unit 45 moves from the current frame to the next frame. That is, the frame memory 67 always holds the image data of the previous frame as the process proceeds.

  In the above description, it has been described that the frame memory 67 holds the image data obtained by decoding the encoded digital image signal. However, the present invention is not limited to this. For example, the image data supplied from the blocking unit 61 May be held in the frame memory 67 after being subjected to predetermined processing.

  In the processing of the first frame, the frame memory 67 does not hold image data or holds frame image data that has nothing to do with it. In such a case, the encoding unit 45 may store the frame image data in the frame memory 67 as it is without performing the encoding process.

  As described above, the encoding unit 45 of the encoding device 33 in FIG. 2 encodes the digital image signal Vdg1 supplied from the A / D 44 and outputs the encoded digital image signal Vcd1. The encoded digital image signal Vcd1 is supplied to the recording unit 46 and recorded on a recording medium, or supplied to the decoding unit 41 and decoded again, and then the image is displayed on the display 43.

  Next, details of the decoding unit 41 of the playback device 31 or the encoding device 33 of FIG. 2 will be described. FIG. 16 is a block diagram illustrating a detailed configuration example of the decoding unit 41 in FIG.

  In FIG. 16, the decoding unit 41 includes a data decomposition unit 201, a four-corner matching block extraction unit 202, a residual decoding unit 203, a pixel value addition unit 204, a block decomposition unit 205, and a frame memory 206. As shown in FIG. 16, each processing unit surrounded by a dotted line 210, that is, the data decomposing unit 201 to the block decomposing unit 205 has the same configuration as the local decoding unit 66 described with reference to FIG. Since the same processing as that of the decoding unit 66 is performed, the description thereof is omitted.

  Further, the frame memory 206 holds the digital image signal Vdg (image data) that is the output of the block decomposing unit 205, that is, the output of the decoding unit 41, and uses the image data as the previous frame image data as a 4-corner matching block extracting unit. 202. That is, the frame memory 206 corresponds to the frame memory 67 of FIG. 3 and performs the same processing as the frame memory 67.

  That is, the decoding unit 41 decodes the residual encoded by the encoding unit 45, specifies the position of the four corner matching block from the block position data Vcdp, and adds the pixel value to the residual, thereby obtaining the reference Get block image data. Then, the decoding unit 41 rearranges the image data of each block and outputs it as frame image data (digital image signal Vdg).

  Next, processing executed by each device of the image processing system 30 as described above will be described.

  First, encoding processing executed by the encoding unit 45 of the encoding device 33 will be described with reference to the flowchart of FIG.

  When the encoding process is started, the blocking unit 61 acquires the digital image signal Vdg in step S1, and divides each frame image data into blocks of a predetermined size. In step S2, the four-corner matching block detection unit 62 performs a four-corner matching block detection process on the previous frame, and selects a block in which the pixel values at the four corners of the block match or approximate to the pixel values of the reference block of the current frame. To detect. Details of the four corner coincidence block detection process will be described later.

  In step S3, the residual calculation unit 63 performs a residual calculation process, and the difference value of the pixel value of each pixel between the reference block of the current frame and the four corner matching block of the previous frame, that is, between corresponding blocks The difference value (residual) of the pixel values is calculated. Details of the residual calculation process will be described later.

  In step S4, the residual encoding unit 64 performs a residual encoding process, and encodes the residual (difference value) calculated by the process of step S3. Details of the residual encoding process will be described later.

  In step S5, the output unit 65 encodes the block position data Vcdp obtained in the four-corner matching block detection process in step S2 and the encoded data Vcdq obtained in the difference value encoding process in step S4 into an encoded digital image signal. Output as Vcd. In step S6, the output unit 65 determines whether or not to end the encoding process. When it is determined that there is unprocessed image data and the encoding process is not ended, the process proceeds to step S7.

  In step S7, the local decoding unit 66 executes local decoding processing and decodes (decodes) the encoded digital image signal Vcd. In step S8, the frame memory 67 holds the decoded image data as a previous frame image, returns the processing to step S1, and repeats the subsequent processing.

  That is, the encoding unit 45 repeats the processing from step S1 to step S8 to perform encoding processing for all image data. If it is determined in step S6 that the encoding process is to be ended, the output unit 65 ends the encoding process.

  Next, the four corner coincidence block detection process executed in step S2 of FIG. 17 will be described with reference to the flowchart of FIG.

  When the four-corner matching block detection process is started, the pixel value acquisition unit 81 starts from the processing target frame of the image data supplied from the blocking unit 61 at the four corners of the processing target block (reference block) in step S21. Get the pixel value of the pixel. In step S22, the search range setting unit 82 sets a search range in the image data of the previous frame.

  In step S23, the block-of-interest setting unit 83 sets a block of interest within the search range. In step S24, the difference absolute value sum calculation unit 84 calculates the sum of the difference values of the pixel values between the blocks (between the reference block and the four corner matching blocks) for the pixels at the four corners of the block.

  In step S25, the comparison unit 85 compares the calculation result obtained by the process in step S24 with the minimum value candidate held by the minimum value candidate holding unit 86. In step S26, the comparison unit 85 determines whether the calculation result is smaller than the minimum value candidate. If it is determined that the calculation result is smaller, the comparison unit 85 advances the process to step S 27, and the minimum value candidate information held by the minimum value candidate holding unit 86 and the four corner matching block candidate holding unit 87. The information on the four-corner matching block candidates held is updated, and the calculation result obtained this time is held. When the process of step S27 ends, the comparison unit 85 advances the process to step S28.

  If it is determined in step S26 that the calculation result is not smaller than the minimum value candidate, the comparison unit 26 advances the process to step S28 without updating the information.

  In step S28, the search control unit 88 determines whether or not the entire search range set in step S22 has been searched. If it is determined that the search has not been performed, the process returns to step S23, and the subsequent processing Repeat. That is, the four corner coincidence block detection unit 62 repeats the processing from step S23 to step S28 and searches for all the blocks that can be taken within the inspection range as to whether or not the four corner coincidence block is obtained.

  If it is determined in step S28 that the entire search range has been searched, the search control unit 88 advances the process to step S29. In step S29, the block position data calculation unit 89 calculates block position data of the four corner matching block.

  When the process of step S29 ends, the block position data calculation unit 89 ends the four corner coincidence block detection process, returns the process to step S2 of FIG. 17, and executes the subsequent processes.

  Next, the flow of the residual calculation process executed in step S3 in FIG. 17 will be described with reference to the flowchart in FIG.

  When the residual calculation process is started, the block extraction unit 101 extracts four corner matching blocks from the image data of the previous frame in step S41 based on the supplied block position data. In step S42, the pixel determination unit 102 checks the position of the target pixel to be processed, and in step S43, determines whether the target pixel is a pixel at the four corners of the block. If it is determined that the pixels for which the difference value is to be calculated are not the four corner pixels of the block, the pixel determination unit 102 advances the process to step S44.

  In step S44, the difference value calculation unit 103 calculates the difference value of the pixel value between the reference block and the four corner matching block for the pixel. When the difference value is calculated, the difference value calculation unit 103 advances the process to step S46.

  If it is determined in step S42 that the target pixel is a pixel at the four corners of the block, the pixel determination unit 102 advances the process to step S45. In step S45, the difference value setting unit 104 sets the difference value of the pixel to “0”, and the process proceeds to step S46.

  In step S46, the residual output unit 105 outputs the difference value obtained in the process of step S44 or step S45 as a residual. In step S <b> 47, the residual output unit 105 determines whether to end the residual calculation process. When it is determined that there is unprocessed image data and the residual calculation process is not ended, the residual output unit 105. Returns the processing to step S41 and repeats the subsequent processing. If it is determined in step S47 that the residual calculation process is to be ended, the residual output unit 105 ends the residual calculation process, returns the process to step S3 in FIG. 17, and executes the subsequent processes.

  Next, the flow of the residual encoding process executed in step S4 of FIG. 17 will be described with reference to the flowchart of FIG.

  When the residual encoding process is started, the DST conversion unit 121 performs DST conversion processing on the residual supplied from the residual calculation unit 63 in step S61. In step S62, the quantization unit 122 performs a quantization process on the coefficient data subjected to DST conversion. In step S <b> 63, the Huffman encoding unit 123 performs Huffman encoding processing on the quantized coefficient data obtained by quantization, generates encoded data Vcdq, and supplies it to the output unit 65.

  In step S64, the Huffman encoding unit 123 determines whether or not to end the residual encoding process, and when it is determined that there is residual data that has not been encoded and the residual encoding process is not to be ended. The process returns to step S61, and the subsequent processes are repeated. If it is determined in step S64 that all the residual data have been encoded and the residual encoding process is to be ended, the Huffman encoding unit 123 ends the residual encoding process, and the step of FIG. The processing is returned to S4, and the subsequent processing is executed.

  Next, the flow of local decoding processing executed in step S7 in FIG. 17 will be described with reference to the flowchart in FIG.

  When the local decoding process is started, the data decomposing unit 141 acquires the encoded digital image signal Vcd in step S81 and separates it into block position data Vcdp and encoded data Vcdq. In step S82, the four corner matching block extraction unit 142 extracts four corner matching blocks from the previous frame image data.

  In step S83, the residual decoding unit 143 performs a residual decoding process, decodes the encoded data Vcdq, and obtains residual data. Details of the residual decoding process will be described later. In step S84, the pixel value addition unit 144 performs addition calculation processing, and performs addition calculation processing of the four corner matching block and the residual (residual in the reference block). Details of the addition calculation processing will be described later.

  In step S85, the block decomposing unit 145 rearranges the addition results and outputs them to the frame memory 67 as frame image data (image data of the previous frame).

  In step S86, the block decomposing unit 145 determines whether or not to end the local decoding process. If it is determined that there is unprocessed encoded data and the local decoding process is not ended, the process returns to step S81. Repeat the subsequent processing. That is, each processing unit of the local decoding unit 66 performs the decoding process on all the frame image data by repeatedly executing the processes in steps S81 to S86.

  If it is determined in step S86 that all encoded data is decoded and the local decoding process is terminated, the block decomposing unit 145 terminates the local decoding process, and returns the process to step S7 in FIG. The subsequent processing is executed.

  Next, the flow of the residual decoding process executed in step S83 in FIG. 21 will be described with reference to the flowchart in FIG.

  When the residual decoding process is started, the Huffman decoding unit 161 performs the Huffman decoding process on the encoded data Vcdq in step S101 to obtain quantized coefficient data. In step S102, the inverse quantization unit 162 performs inverse quantization on the quantized coefficient data obtained by the Huffman decoding process, and obtains coefficient data of the block subjected to DST conversion. In step S103, the IDST conversion unit 163 performs IDST conversion processing, obtains residual data of the reference block before returning DST, and outputs it. In step S104, the IDST conversion unit 163 determines whether or not to end the residual decoding process. If it is determined that there is unprocessed encoded data Vcdq and the residual decoding process is not ended, the process proceeds to step S101. Return to, and repeat the subsequent processing. If it is determined in step S104 that the residual decoding process is to be ended, the IDST conversion unit 163 ends the residual decoding process, returns the process to step S83 in FIG. 21, and executes the subsequent processes.

  Next, the flow of the addition calculation process executed in step S84 in FIG. 21 will be described with reference to the flowchart in FIG.

  When the addition calculation process is started, first, in step S121, the pixel determination unit 181 confirms the position of the processing target pixel to be subjected to the addition calculation in the block, and in step S122, the target pixel is located at the four corners of the block. It is determined whether or not it is a pixel. If it is determined that the pixel is at the four corners of the block, the pixel determination unit 181 advances the process to step S123.

  In step S123, the residual setting unit 182 sets the residual to “0” and advances the process to step S124.

  If it is determined in step S122 that the target pixel is not a pixel at the four corners of the block, the pixel determination unit 181 skips step S123 and proceeds to step S124.

  In step S124, the addition value calculation unit 183 adds the image data of the four-corner matching block and the residual, and causes the order alignment unit 184 to hold the added result. In step S125, the order aligning unit 184 determines whether or not to end the addition calculation process. When it is determined that there is an unprocessed pixel and the addition calculation process is not ended, the process returns to step S121, and thereafter Repeat the process.

  That is, each processing unit of the pixel value adding unit 144 repeats the processing from step S121 to step S125, and performs addition processing on all the pixels in the block. If it is determined in step S125 that addition processing has been performed for all pixels, the order aligning unit 184 rearranges the addition results for each pixel in raster order and outputs the result as block image data in step S126. When the process of step S126 is finished, the order arranging unit 184 finishes the addition operation process.

  Next, the decoding process executed by the decoding unit 41 will be described with reference to the flowchart of FIG. As described with reference to FIG. 16, the data decomposition unit 201 to block decomposition unit 205 (the processing unit surrounded by the dotted line 210) of the decoding unit 41 in FIG. 16 is the configuration of the local decoding unit 66 (FIG. 13). It is the same. Accordingly, each unit of the decoding unit 41 executes the processing from step S141 to step S146 in FIG. 24 in the same manner as the processing from step S81 to step S86 in FIG.

  That is, when the decoding process is started, the data decomposing unit 201 acquires the encoded digital image signal Vcd and separates the encoded data Vcdq and the block position data Vcdp in step S141. In step S142, the four corner matching block extraction unit 202 extracts four corner matching blocks from the previous frame image data. The residual decoding unit 203 performs a residual decoding process in step S143 to decode the encoded data. The details of the residual decoding process have been described above with reference to the flowchart of FIG. In step S <b> 144, the pixel value adding unit 204 performs an addition calculation process of the four corner matching block and the residual. The details of the addition calculation processing have been described above with reference to the flowchart of FIG.

  In step S145, the block decomposing unit 205 rearranges the addition results, generates a frame image, and outputs the frame image. In step S146, the block decomposition unit 205 determines whether or not to end the decoding process. When it is determined that there is an unprocessed frame image and the decoding process is not finished, the block decomposing unit 205 advances the process to step S147.

  In step S147, the frame memory 206 holds the frame image data output from the block decomposition unit 205 as the image data of the previous frame. When the process of step S147 ends, the frame memory 206 returns the process to step S141 and repeats the subsequent processes.

  If it is determined in step S146 that the decoding process is to be terminated, the block decomposing unit 205 ends the decoding process.

  As described above, the encoding unit 45 and the decoding unit 41 positively use analog distortion such as white noise and phase shift generated in an analog signal, intentionally generate large analog distortion, and image quality is improved by the analog distortion. Since the encoding process and the decoding process are performed so as to deteriorate, the image can be greatly deteriorated every time the encoding process and the decoding process are repeated.

  For example, in the image processing system 30 of FIG. 2, assuming that the analog image signal Van1 is distorted by white noise (particularly, high-frequency components) mixed during D / A conversion by the D / A 42, the A / D by the A / D 44 is used. Since the pixel data slightly fluctuates every time (every frame) at the time of conversion, the pixel values of the four corners of each block obtained by being blocked by the encoding unit 45 are the values for the first encoding and decoding. (The pixel values at the four corners of each block are different each time).

  Therefore, the four-corner matching block detection unit 62 of the encoding unit 45 sets a block at a position different from the block detected by the first encoding as a four-corner matching block. Accordingly, the block position data calculated by the four corner coincidence block detection unit 62 is different from the block position data calculated in the first encoding.

  That is, the residual calculation unit 63 calculates a residual different from the first encoding. The residual encoding unit 64 encodes the residual, and at this time, a new quantization distortion different from the quantization distortion generated in the first encoding is generated. Thus, every time encoding and decoding are repeated, a different quantization distortion occurs in the image data, and as a result, the image data includes a large distortion.

  Therefore, for example, the digital image signal Vdg2 obtained by decoding the encoded digital image signal Vcd1 recorded on the recording medium by the recording unit 46 is compared with the digital image signal Vdg0 obtained from the decoding unit 41 of the playback device 31. It will be greatly deteriorated. In other words, the image quality of the digital image signal Vdg2 is greatly degraded compared to that of the digital image signal Vdg0.

  That is, for example, when the reproduction device 31 reproduces the encoded digital image signal Vcd1 read from the recording unit 46 (the analog image signal Van1 output from the reproduction device 31 is encoded and decoded for the second time or later). The image data encoded by the encoding unit 45 as described above and further decoded by the decoding unit 41 (the image of the analog image signal Van2 D / A converted by the D / A 42) Data) has undergone the third and subsequent encoding processing and decoding processing, and the image quality is further deteriorated.

  As described above, the image quality obtained by reproducing the encoded digital image signal Vcd1 recorded on the recording medium by the recording unit 46 is significantly higher than the image by the analog image signal Van1 output from the reproduction device 31. It becomes deteriorated. Therefore, the encoding device 33 cannot replicate the analog image signal output from the reproduction device 31 while maintaining the good image quality of the image.

  Note that, for example, a noise component is generated in an analog image signal by repeating the encoding process and the decoding process with a conventional method, and simultaneously repeating the A / D conversion process and the D / A conversion process, so that the image quality gradually increases. However, this is merely the accumulation of noise components, which is different from the encoding processing and decoding processing by the image processing system 30 to which the present invention is applied.

  In other words, image quality degradation when the noise component is simply accumulated usually does not cause the image to break down if the S / N ratio is sufficiently low (the picture content cannot be understood). Further, it is easy to remove the noise component (improve image quality). On the other hand, in the encoding process of the present invention, as described above, analog distortion is used to generate a large distortion and corrupt the image (the image quality is greatly degraded). It is possible to obtain an effect different from “simply increasing the amount of noise and increasing the S / N ratio”.

  In addition, since the image quality is greatly deteriorated in the encoding process in this way, the image of the image signal before duplication is displayed normally without failure as in the case where the display device 32 displays an image on the display 43, for example. Is done.

  That is, the encoding unit 45 can prevent only a good quality copy of the analog signal without requiring a special process such as a scramble process or embedding noise information. As a result, the encoding device 33 can suppress illegal copying using an analog signal without causing inconveniences such as an image not being displayed and an increase in circuit scale.

  Further, the decoding unit 41 performs a decoding process so as to correspond to such an encoding unit 45, and the encoding unit 45 actively uses analog distortion such as white noise and phase shift generated in the analog signal. Since the decoding process is performed so that a large analog distortion added intentionally remains in the image signal, only a good quality copy of the analog signal is required without special processing such as scramble processing or embedding noise information. Can be prevented. As a result, the decoding device 31 can suppress illegal copying using an analog signal without causing inconveniences such as an image not being displayed and an increase in circuit scale.

  If there is no analog distortion (for example, when the digital image signal Vdg0 output from the decoding unit 41 is directly encoded), white noise does not occur in the signal, so the pixel values of the pixels at the four corners of the block are: There is no change in the first encoding process or the second encoding process. Further, since the residual of this pixel is set to “0” every time, an error due to the addition calculation process does not occur. Therefore, the same block as the first time is detected as a four-corner matching block no matter how many times the encoding process (decoding process) is performed, and the encoding unit 45 can perform any number of encoding processes. Thus, substantially the same encoded data can be obtained. In other words, the decoding unit 41 decodes substantially the same encoded data regardless of the number of decoding processes, and can be reproduced with normal quality.

  As described above, in the image processing system 30, the encoding device 33 cannot copy the analog image signal output from the reproduction device 31 so as not to deteriorate the image quality of the image. Accordingly, the image processing system 30 can suppress illegal copying using an analog signal and safely output the analog signal without causing inconveniences such as an increase in circuit scale and cost. Further, for example, when copying using a digital signal, such as copying in editing work, the image processing system 30 can perform copying without degrading image quality. In this case, D / A 42 and A / D 44 are omitted from the image processing system 30. Also, in this case, copyright management can be performed by using other technologies such as DRM (Digital Rights Management) together, so that the image processing system 30 can also prevent unauthorized duplication of digital signals. it can.

  In the above description, when matching is performed between the current frame block and the previous frame block, the pixels that are actually compared are described as the four corner pixels of each block. The number of pixels may be any number. However, if the arrangement of pixels to be compared is gathered in one place, the matching accuracy with respect to other parts of the block is lowered. That is, if the pixels to be compared are scattered throughout the block, matching accuracy can be improved (error can be reduced), and matching can be performed more accurately. Also, the more pixels that are compared, the more accurately matching can be performed, but the processing load increases accordingly.

  In the above description, the DST conversion process is described as the residual encoding method. However, the present invention is not limited to this. For example, the function approximation encoding that approximates the residual waveform with a function and transmits the coefficient is performed. You may make it use.

  FIG. 25 is a block diagram showing a detailed configuration example of the residual encoding unit 64 (FIG. 3) in that case, and corresponds to FIG.

  In FIG. 25, the residual encoding unit 64 has a function approximation conversion unit 231 instead of the DST conversion unit 121 (FIG. 10). 25 also includes a quantizing unit 122 and a Huffman coding unit 123, as in the case of FIG.

  As shown in FIG. 26, the function approximating transformation unit 231 represents each pixel position in coordinates as shown in FIG. 26, and approximates a waveform composed of each pixel value to, for example, a three-dimensional function. Is represented by

  For example, in the case of FIG. 26, the function approximation conversion unit 231 coordinates the position of each pixel with the lower left pixel of the block as the reference point, the horizontal direction as the x axis, and the vertical direction as the y axis (in the case of FIG. 26). 0 ≦ x ≦ 7, 0 ≦ y ≦ 7). Next, the function approximation conversion unit 231 converts the waveform formed by the pixel values of each pixel into a function using an approximation function. For example, the function approximation conversion unit 231 approximates a three-dimensional function represented by the following expression (4) to a pixel value waveform by using a least square method or the like.

  Since the residual values at the four corners of the block are set to “0” by the residual calculation unit 63, the following formula (5) is added to the formula (4).

  Z (0,0) = Z (0,7) = Z (7,0) = Z (7,7) = 0 (5)

  The function approximation conversion unit 231 calculates coefficients a to i when the function of Expression (4) is approximated to the waveform of the pixel value by performing a least square method, and the coefficients a to i are used as coefficient data. This is supplied to the quantization unit 122.

  The quantization unit 122 quantizes the supplied coefficient data as in the case of FIG. Similarly to the case of FIG. 10, the Huffman encoding unit 123 also encodes the quantized coefficient data obtained in the quantizing unit 122 to generate encoded data.

  In this case, the residual decoding unit 143 (FIG. 13) of the local decoding unit 66 (FIG. 3) and the residual decoding unit 203 (FIG. 16) of the decoding unit 41 (FIG. 2) correspond to this function approximate conversion process. The decoding process is performed by the method.

  FIG. 27 is a block diagram illustrating a detailed configuration example of the residual decoding unit 143 in that case, and corresponds to FIG. The residual decoding unit 203 has the same configuration as that of the residual decoding unit 143 and performs the same processing, so that the description thereof is omitted.

  In FIG. 27, the residual decoding unit 143 includes a Huffman decoding unit 161 and an inverse quantization unit 162 as in FIG. 14, and an inverse function approximation conversion unit 232 is used instead of the IDST conversion unit 163 in FIG. Have.

  The inverse function approximation transform unit 232 generates an approximate function using the coefficient data obtained by the inverse quantization process by the inverse quantization unit 162 (substituting the coefficient data into the equation (4)), and uses the approximate function from the approximate function. The pixel value with each pixel is calculated. That is, the inverse function approximate conversion unit 232 calculates each pixel value (residual) by substituting the x coordinate and the y coordinate for the variables X and Y of the approximate function (formula (4)), respectively.

  The flow of the residual encoding process using the function approximation transformation as described above will be described with reference to the flowchart of FIG. This flowchart corresponds to the flowchart of FIG.

  In other words, when the residual encoding process is started, the function approximation conversion unit 231 performs the function approximation conversion process on the supplied residual in step S161, and is configured by the residual of each pixel for each block. The generated waveform is converted into a function, and coefficient data of an approximate function is generated. In step S162, the quantization unit 122 performs a quantization process on the coefficient data in the same manner as in step S62 in FIG. 20, and generates quantized coefficient data. In step S163, the Huffman encoding unit 123 performs Huffman encoding processing on the quantized coefficient data in the same manner as in step S63 of FIG. 20, and generates encoded data Vcdq.

  In step S164, the Huffman encoding unit 123 determines whether or not to end the residual encoding process, and determines that there is an unprocessed residual and does not end the residual encoding process. Returning to step 161, the subsequent processing is repeated. If it is determined in step S164 that the residual encoding process is to be ended, the Huffman encoding unit 123 ends the residual encoding process, returns the process to step S4 in FIG. 17, and executes the subsequent processes. Let

  Next, with reference to the flowchart in FIG. 29, a decoding process corresponding to the encoding process described with reference to the flowchart in FIG. 28, that is, the flow of the decoding process using the function approximate conversion process will be described. The flowchart of FIG. 29 corresponds to the flowchart of FIG.

  When the residual decoding process is started, in step S181, the Huffman decoding unit 161 performs the Huffman decoding process on the encoded data Vcdq in the same manner as in step S101 in FIG. 22, and generates quantized coefficient data. In step S182, the inverse quantization unit 162 performs inverse quantization processing on the quantized coefficient data, similarly to step S102 in FIG. 22, and generates coefficient data. In step S183, the inverse function approximation conversion unit 232 performs an inverse function conversion process, and calculates the original pixel value (residual) from the coefficient data.

  In step S184, the inverse function approximation conversion unit 232 determines whether or not to end the residual decoding process. For example, when it is determined that there is unprocessed encoded data and the residual decoding process is not to be ended, Is returned to step S181, and the subsequent processing is repeated. If it is determined in step S164 that the residual decoding process is to be terminated, the inverse function approximation conversion unit 232 terminates the residual decoding process, returns the process to step S83 in FIG. 21, and performs the subsequent processes. Let it run.

  As described above, by using the function approximate conversion process and the inverse function approximate conversion process, the encoding unit 45 only performs replication using an analog signal, as in the case of performing the DST conversion process and the IDST conversion process. The quality of information can be degraded. Accordingly, in this case, the encoding device 33 does not cause inconveniences such as an increase in circuit scale, and the image data is significantly deteriorated in the second and subsequent encoding processes and the analog signal is used. Unauthorized copying can be suppressed.

  In this way, the decoding unit 41 performs the inverse function approximate conversion process in response to the function approximate conversion process and the inverse function approximate conversion process of the encoding unit 45, and therefore, similarly to the case of performing the IDST conversion process, the analog signal is converted. The quality of information can be deteriorated only when copying is performed. Accordingly, in this case, the reproducing device 31 also does not cause inconveniences such as an increase in circuit scale, and the image data is significantly deteriorated in the second and subsequent encoding processing and decoding processing. Copying can be suppressed.

  That is, even when the encoding unit 45 performs the function approximate conversion process and the inverse function approximate conversion process and the decoding unit 41 performs the inverse function approximate conversion process, the image processing system 30 may increase the circuit scale, increase the cost, and the like. Without causing inconvenience, unauthorized copying using an analog signal can be suppressed and the analog signal can be output safely.

  Even in this case, the image processing system 30 can perform the copying without degrading the image quality when the copying is performed using the digital signal, for example, in the editing work. Further, for example, by using another technique such as DRM together, the image processing system 30 can also suppress unauthorized duplication of digital signals.

  The configuration of each device of the image processing system 30 may be other than that shown in FIG. 2, for example, as shown in FIG. 30, the decoding unit 41, the D / A 42, and the display of the encoding device 33 43 may be omitted.

  FIG. 30 is a diagram showing another configuration example of the image processing system to which the present invention is applied, and corresponds to FIG. That is, the image processing system 250 in FIG. 30 corresponds to the image processing system 30 in FIG. 2, and includes an encoding device 253 instead of the encoding device 33 in the image processing system 30.

  The encoding device 253 is a device corresponding to the encoding device 33 in FIG. 2, and has a configuration in which the decoding unit 41, the D / A 42, and the display 43 are omitted from the configuration of the encoding device 33.

  That is, the encoding device 253 of the image processing system 250 obtains the analog image signal Van1 output from the reproduction device 31, and digitizes and encodes the encoded digital image, similarly to the encoding device 33 of FIG. It only generates the signal Vcd1 and records it on a recording medium. Like the encoding device 33, it decodes the encoded digital image signal again, generates the analog image signal Van2, and displays the image on the display 43. I won't do that.

  The encoding device 33 in FIG. 2 has a configuration applied for convenience in order to describe a case where the encoded image signal is decoded again. In practice, it is sufficient if encoding can be performed, and such a configuration is necessary. Not really.

  Further, in FIG. 2 (FIG. 30), the configuration of each device described as one device may be configured as a plurality of devices, or conversely, a plurality of devices may be configured as one device. Also good.

  FIG. 31 is a diagram showing still another configuration example of the image processing system to which the present invention is applied. An image processing system 260 in FIG. 31 corresponds to the image processing system 30 in FIG. In FIG. 31, the image processing system 260 includes two decoding devices 261, two display devices 262, an A / D conversion device 263, an encoding device 264, and a recording device 265.

  The decoding device 261 has a decoding unit 41, the display device 262 has a D / A 42 and a display 43, the A / D conversion device 263 has an A / D 44, and the encoding device 264 has an encoding unit 45. The recording device 265 has a recording unit 46.

  That is, the image processing system 260 is the same as the image processing system 30 in FIG. 2 except for the configuration of the apparatus. Accordingly, since the image processing system 260 performs the same processing as the image processing system 30 by each device, similarly to the image processing system 30, it is possible to suppress unauthorized duplication of content data using analog signals.

  Moreover, you may make it add the structure other than the structure mentioned above to the image processing system of FIG. For example, a noise component (analog distortion such as white noise or phase shift) may be positively added to the analog image signal Van so that the image quality is significantly deteriorated when the analog image signal is copied. However, this noise component is not simply added to improve the S / N ratio, but to further deteriorate the image quality in the encoding process or decoding process described above (to cause a large distortion in the image signal). It is added for active use.

  FIG. 32 is a diagram showing still another configuration example of the image processing system to which the present invention is applied, and corresponds to FIGS. 2 and 31.

  In FIG. 32, the image processing system 280 includes two playback devices 281, an encoding device 282, two display devices 32, and a recording device 265. As described with reference to FIG. 2, the display device 32 is a device that displays the image of the analog image signal Van <b> 1 or Van <b> 2 output from the playback device 281 on the display 43. As described with reference to FIG. 31, the recording device 265 includes the recording unit 46, and records the encoded digital image signal Vcd <b> 1 output from the encoding device 282 on the recording medium of the recording unit 46.

  The playback device 281 includes a decoding unit 41 and a D / A 42 as well as the playback device 31, and further includes an analog noise addition unit 291. The analog noise adding unit 291 adds a noise component (analog noise) to the analog image signal converted by the D / A 42.

  Here, the analog noise is a noise component added to the analog signal, and is a noise component with respect to the analog component. In other words, the analog noise is a noise component that generates analog distortion (analog component distortion) such as white noise and phase shift.

  That is, the playback device 281 outputs an analog image signal Van to which analog noise is positively added. For example, the playback device 281 generates an analog image signal Van1 to which analog noise is positively added from the encoded digital image signal Vcd0. For example, the playback device 281 generates an analog image signal Van2 to which analog noise is positively added from the encoded digital image signal Vcd1.

  The encoding device 282 includes an A / D 44 and an encoding unit 45 as well as the encoding device 33 of FIG. 2, and further includes an analog noise adding unit 291. That is, the encoding device 282 performs A / D conversion on the analog image signal to which analog noise is positively added in the analog noise adding unit 291 in the A / D 44 and encodes it in the encoding unit 45.

  In the image processing system 280 of FIG. 32, an analog deterioration coding process that is performed by the coding apparatus 282 and adds analog noise to an analog image signal and performs coding will be described with reference to the flowchart of FIG. .

  First, in step S201, the analog noise adding unit 291 adds analog noise (white noise, phase shift, etc.) to the analog image signal Van output from the playback device 281. In step S202, the encoding device 282 performs A / D conversion processing on the analog image signal Van to which analog noise is positively output, which is output from the analog noise adding unit 291 to generate a digital image signal Vdg. To do. In step S203, the encoding unit 45 performs an encoding process. Since this encoding process is the same as the encoding process described with reference to the flowchart of FIG. 17, a detailed description thereof is omitted.

  When the encoding process ends, the encoding unit 45 proceeds to step S204, determines whether to end the analog deterioration encoding process, and returns to step S201 if it determines not to end the process. The subsequent processing is repeated. If it is determined in step S204 that the analog deterioration encoding process is to be ended, the encoding unit 45 ends the analog deterioration encoding process.

  Next, an analog deterioration decoding process for positively adding analog noise to the decoded analog image signal, which is executed by the playback device 281 in the image processing system 280 of FIG. 32, will be described with reference to the flowchart of FIG.

  First, in step S221, the decoding unit 41 performs a decoding process on the input encoded digital image signal. Since this decoding process is the same as the decoding process described with reference to the flowchart of FIG. 24, a detailed description thereof is omitted.

  When the decoding process is completed and the digital image signal Vdg is obtained, the D / A 42 performs a D / A conversion process on the digital image signal Vdg in step S222 to obtain an analog image signal Van. In step S223, the analog noise adding unit 291 adds analog noise (white noise, phase shift, etc.) to the analog image signal Van D / A converted in the D / A 42.

  When the analog noise is added, the analog noise adding unit 291 advances the process to step S224, determines whether or not to end the analog degradation decoding process, and returns to step S221 if determined not to end, and thereafter Repeat the process. If it is determined in step S224 that the analog degradation decoding process is to be terminated, the analog degradation decoding process is terminated.

  As described above, the playback device 281 and the encoding device 282 positively add analog noise to the analog image signal. Accordingly, when copying is performed using an analog signal in the image processing system 280, noise is positively added to the analog image signal by repeating the encoding process and the decoding process, and the image quality of the image is further improved. Since the deterioration significantly occurs, the encoding device 282 and the reproduction device 241 can perform the encoding process and the decoding process so as to further suppress unauthorized duplication of content data using an analog signal.

  That is, the image processing system 280 does not cause inconveniences such as an image not being displayed and an increase in circuit scale, and the image data is deteriorated significantly in the second and subsequent encoding processes. It is possible to further suppress unauthorized copying using.

  The series of processes described above can be executed by hardware or can be executed by software. In this case, for example, the devices constituting the image processing system 30 in FIG. 2, the image processing system 250 in FIG. 30, the image processing system 260 in FIG. 31, and the image processing system 280 in FIG. 32 are shown in FIG. It may be configured as such a personal computer.

  In FIG. 35, a CPU (Central Processing Unit) 301 of the personal computer 300 performs various processes according to a program stored in a ROM (Read Only Memory) 302 or a program loaded from a storage unit 313 to a RAM (Random Access Memory) 303. Execute the process. The RAM 303 also appropriately stores data necessary for the CPU 301 to execute various processes.

  The CPU 301, ROM 302, and RAM 303 are connected to each other via a bus 304. An input / output interface 310 is also connected to the bus 304.

  The input / output interface 310 includes an input unit 311 including a keyboard and a mouse, a display including a CRT (Cathode Ray Tube) and an LCD (Liquid Crystal Display), an output unit 312 including a speaker, and a hard disk. A communication unit 314 including a storage unit 313 and a modem is connected. The communication unit 314 performs communication processing via a network including the Internet.

  A drive 315 is connected to the input / output interface 310 as necessary, and a removable medium 321 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory is appropriately mounted, and a computer program read from them is It is installed in the storage unit 313 as necessary.

  When the above-described series of processing is executed by software, a program constituting the software is installed from a network or a recording medium.

  For example, as shown in FIG. 35, this recording medium is distributed to distribute the program to the user separately from the apparatus main body, and includes a magnetic disk (including a flexible disk) on which the program is recorded, an optical disk ( Removable media 321 composed of CD-ROM (compact disk-read only memory), DVD (digital versatile disk), magneto-optical disk (including MD (mini-disk) (registered trademark)), or semiconductor memory In addition to being configured, it is configured by a ROM 302 on which a program is recorded, a hard disk included in the storage unit 313, and the like distributed to the user in a state of being incorporated in the apparatus main body in advance.

  In the present specification, the step of describing the program recorded on the recording medium is not limited to the processing performed in chronological order according to the described order, but is not necessarily performed in chronological order. It also includes processes that are executed individually.

  Further, in this specification, the system represents the entire apparatus composed of a plurality of devices (apparatuses).

It is a figure which shows the structural example of the conventional image processing system. It is a figure which shows the structural example of the image processing system to which this invention is applied. It is a block diagram which shows the example of an internal structure of the encoding part of FIG. It is a schematic diagram explaining the example of a mode that frame image data is made into a block. It is a schematic diagram which shows the pixel of the four corners of a reference | standard block. It is a block diagram which shows the structural example of the 4 corner coincidence block detection part of FIG. It is a schematic diagram which shows the mode of the setting of a search range. It is a schematic diagram which shows the mode of calculation of block position data. It is a block diagram which shows the structural example of the residual calculation part of FIG. It is a block diagram which shows the structural example of the residual encoding part of FIG. It is a figure which shows the example of 1-dimensional DST conversion. It is a figure which shows the example of two-dimensional DST conversion. It is a block diagram which shows the structural example of the local decoding part of FIG. It is a block diagram which shows the structural example of the residual decoding part of FIG. It is a block diagram which shows the structural example of the pixel value addition part of FIG. It is a block diagram which shows the structural example of the decoding part of FIG. It is a flowchart explaining the example of an encoding process. It is a flowchart explaining the example of a four corner coincidence block detection process. It is a flowchart explaining the example of a residual calculation process. It is a flowchart explaining the example of a residual encoding process. It is a flowchart explaining the example of a local decoding process. It is a flowchart explaining the example of a residual decoding process. It is a flowchart explaining the example of an addition calculation process. It is a flowchart explaining the example of a decoding process. It is a block diagram which shows the other structural example of the residual encoding part of FIG. It is a figure explaining the mode of function approximate conversion. It is a block diagram which shows the other structural example of the residual decoding part of FIG. It is a flowchart explaining the other example of a residual encoding process. It is a flowchart explaining the other example of a residual decoding process. It is a figure which shows the other structural example of the image processing system to which this invention is applied. It is a figure which shows the further another structural example of the image processing system to which this invention is applied. It is a figure which shows the further another structural example of the image processing system to which this invention is applied. It is a flowchart explaining the example of an analog degradation encoding process. It is a flowchart explaining the example of an analog degradation decoding process. It is a figure which shows the structural example of the personal computer to which this invention is applied.

Explanation of symbols

  30 image processing system, 31 playback device, 33 encoding device, 41 decoding unit, 42 D / A, 44 A / D, 45 encoding unit, 61 blocking unit, 62 4-corner matching block detection unit, 63 residual calculation , 64 residual encoding unit, 65 output unit, 66 local decoding unit, 67 frame memory, 81 pixel value acquisition unit, 82 search range setting unit, 83 target block setting unit, 84 difference absolute value sum calculation unit, 85 comparison , 86 minimum value candidate holding unit, 87 four corner matching block candidate holding unit, 88 search control unit, 89 block position data calculation unit, 101 block extraction unit, 102 pixel determination unit, 103 difference value calculation unit, 104 difference value setting Part, 105 residual output part, 121 DST conversion part, 122 quantization part, 123 Huffman coding part, 141 data decomposing unit, 142 4-corner matching block extracting unit, 143 residual decoding unit, 144 pixel value adding unit, 145 block decomposing unit, 161 Huffman decoding unit, 162 dequantizing unit, 163 IDST converting unit, 181 pixel determining unit , 182 Residual setting unit, 183 Addition value calculation unit, 184 Order alignment unit, 201 Data decomposition unit, 202 Four corner matching block extraction unit, 203 Residual decoding unit, 204 Pixel value addition unit, 205 Block decomposition unit, 206 frame Memory, 231 function approximate conversion unit, 232 inverse function approximate conversion unit, 250 image processing system, 253 encoding device, 260 image processing system, 261 decoding device, 264 encoding device, 280 image processing system, 281 playback device, 282 encoding 291 analog Noise adding unit, 300 Personal computer

Claims (28)

An encoding device for encoding image data,
Identification of a first frame image that is a processing target frame image of the image data that is a pixel at a predetermined position in the first block that is a processing target block in a block obtained by dividing the frame image into a plurality of regions pixel, a difference absolute value sum calculating means for calculating the sum of the absolute value of the difference of the specific pixel block of the first frame image and different from the second frame image,
Detecting means for detecting, as a second block, a block of the second frame in which the sum of the absolute values of the differences calculated by the difference absolute value sum calculating means is minimum ;
A difference calculating unit that calculates a difference between pixel values of pixels other than the specific pixel between the first block and the second block detected by the detecting unit;
Difference setting means for setting a difference between pixel values of the specific pixels to a predetermined value between the first block and the second block detected by the detection means;
Difference encoding means for encoding, for each block, a difference between pixel values of pixels other than the specific pixel calculated by the difference calculation means and a difference between pixel values of the specific pixels set by the difference setting means. An encoding device comprising: The encoding apparatus according to claim 1, wherein the difference absolute value sum calculation means uses four corner pixels of each block as specific pixels. The encoding apparatus according to claim 1, further comprising a search range setting means for setting a search range for searching the second block in the second frame. Candidate holding means for holding, as a candidate for the minimum value, a minimum value of the sum of absolute values of the differences calculated by the absolute difference value calculating means until then ;
Comparing means for comparing the sum of the absolute values of the differences calculated by the difference absolute value calculating means with the candidate for the minimum value held by the candidate holding means,
The encoding apparatus according to claim 1 , wherein the candidate holding unit holds a sum of absolute values of the difference having a smaller value as a minimum value candidate based on a comparison result by the comparison unit. The encoding apparatus according to claim 1, further comprising a block position calculating means for calculating the relative position based on the position of the first block of the detected second block by said detecting means. The encoding apparatus according to claim 1, wherein the difference setting unit sets the difference of the specific pixel to “0”. The differential encoding means includes
An orthogonal transform unit that orthogonally transforms a difference between pixel values of pixels other than the specific pixel calculated by the difference calculation unit, and a difference between pixel values of the specific pixel set by the difference setting unit;
Quantization means for quantizing coefficient data obtained by orthogonally transforming the difference by the orthogonal transform means;
The encoding apparatus according to claim 1, further comprising: variable length encoding means for variable length encoding the quantized coefficient data obtained by quantizing the coefficient data by the quantization means. The encoding apparatus according to claim 7 , wherein the orthogonal transform unit performs discrete sine transform on the difference. Block position data, which is detected by the detection means, is relative position information of the second block with respect to the position of the first block, and a code obtained by encoding the difference by the difference encoding means The encoding apparatus according to claim 1, further comprising output means for outputting encoded data to the outside of the encoding apparatus. Decoding means for decoding encoded data obtained by encoding the difference by the difference encoding means, and obtaining a frame image based on the block position data;
Frame image holding means for holding a frame image obtained by decoding by the decoding means as the second frame image in the next detection of the second block;
2. The code according to claim 1, wherein the difference absolute value sum calculating unit calculates the sum of absolute values of the differences by using the frame image held by the frame image holding unit as the second frame image. Device. Noise adding means for adding analog noise, which is a noise component with respect to the analog component, to the image data of the analog signal;
A / D conversion means for A / D converting the analog signal image data to which analog noise has been added by the noise addition means to obtain digital data image data, and
The difference absolute value sum calculation means uses a frame image of the image data of the digital data obtained by A / D conversion by the A / D conversion means as the second frame image, and calculates the absolute value of the difference. The encoding apparatus according to claim 1, wherein a sum of the two is calculated . An encoding method of an encoding device for encoding image data,
Identification of a first frame image that is a processing target frame image of the image data that is a pixel at a predetermined position in the first block that is a processing target block in a block obtained by dividing the frame image into a plurality of regions a pixel, and the sum of absolute differences calculation step of calculating a sum of absolute values of differences between each particular pixel block of the first frame image and different from the second frame image,
A detection step of detecting, as a second block, a block of the second frame in which the sum of absolute values of the differences calculated by the processing of the difference absolute value sum calculation step is minimized ;
A difference calculating step of calculating a difference between pixel values of pixels other than the specific pixel between the first block and the second block detected by the processing of the detecting step;
A difference setting step of setting a difference between pixel values of the specific pixels to a predetermined value between the first block and the second block detected by the processing of the detection step;
The pixel value difference of pixels other than the specific pixel calculated by the difference calculating step and the pixel value difference of the specific pixel set by the difference setting step are encoded for each block. An encoding method comprising: a differential encoding step. A computer for encoding image data;
Identification of a first frame image that is a processing target frame image of the image data that is a pixel at a predetermined position in the first block that is a processing target block in a block obtained by dividing the frame image into a plurality of regions pixel, a difference absolute value sum calculating means for calculating the sum of absolute values of differences between each particular pixel block of the first frame image and different from the second frame image,
Detecting means for detecting, as a second block, a block of the second frame in which the sum of the absolute values of the differences calculated by the difference absolute value sum calculating means is minimum ;
A difference calculating unit that calculates a difference between pixel values of pixels other than the specific pixel between the first block and the second block detected by the detecting unit;
Difference setting means for setting a difference between pixel values of the specific pixels to a predetermined value between the first block and the second block detected by the detection means;
Difference encoding means for encoding, for each block, a difference between pixel values of pixels other than the specific pixel calculated by the difference calculation means and a difference between pixel values of the specific pixels set by the difference setting means. A computer-readable recording medium on which a program that functions as a computer is recorded. A computer for encoding image data;
Identification of a first frame image that is a processing target frame image of the image data that is a pixel at a predetermined position in the first block that is a processing target block in a block obtained by dividing the frame image into a plurality of regions pixel, a difference absolute value sum calculating means for calculating the sum of absolute values of differences between each particular pixel block of the first frame image and different from the second frame image,
Detecting means for detecting, as a second block, a block of the second frame in which the sum of the absolute values of the differences calculated by the difference absolute value sum calculating means is minimum ;
A difference calculating unit that calculates a difference between pixel values of pixels other than the specific pixel between the first block and the second block detected by the detecting unit;
Difference setting means for setting a difference between pixel values of the specific pixels to a predetermined value between the first block and the second block detected by the detection means;
Difference encoding means for encoding, for each block, a difference between pixel values of pixels other than the specific pixel calculated by the difference calculation means and a difference between pixel values of the specific pixels set by the difference setting means. Program to function as. A decoding device for decoding image data,
The first frame image that is the processing target frame image of the image data and the first block that is the processing target block among the blocks obtained by dividing the frame image into a plurality of regions. The first block of the second block, which is a block of a second frame image different from the first frame image, in which the sum of the absolute values of the pixel value differences in the specific pixel that is the position pixel is minimized. based on the block position data is relative position information for the block, extracting means for extracting the second blocks from said second frame image,
Differential decoding means for decoding encoded data in which a pixel value difference is encoded between each pixel of the first block and each pixel of the second block, and obtaining a pixel value difference of each pixel ;
A discriminating unit for discriminating a pixel value difference of the specific pixel from a pixel value difference of each pixel obtained by decoding the encoded data by the difference decoding unit;
Difference setting means for setting a difference between pixel values of the specific pixels determined by the determination means to a predetermined value;
The extraction means extracts the difference between the pixel values of the specific pixels for which the predetermined value has been set by the difference setting means and the difference between the pixel values of the pixels other than the specific pixels that were not determined by the determination means. And a pixel value adding means for adding the pixel value of the second block for each pixel to obtain the first block. The decoding device according to claim 15 , wherein the specific pixels are pixels at four corners of the block. The differential decoding means includes
Variable length decoding means for variable length decoding the encoded data;
Inverse quantization means for inversely quantizing quantized coefficient data obtained by variable length decoding the encoded data by the variable length decoding means;
The decoding apparatus according to claim 15 , further comprising: an inverse orthogonal transform unit that performs inverse orthogonal transform on coefficient data obtained by dequantizing the quantized coefficient data by the inverse quantization unit. The decoding apparatus according to claim 17 , wherein the orthogonal transform means performs inverse discrete sine transform on the coefficient data. The decoding device according to claim 15 , wherein the difference setting means sets a difference between the specific pixels to "0". The decoding apparatus according to claim 15 , further comprising: an order alignment unit that rearranges pixel values of each pixel obtained as an addition result by the pixel value addition unit in raster order for each block. The decoding device according to claim 15 , further comprising an output unit that holds the first block obtained by the addition by the pixel value addition unit and outputs the first block to the outside of the decoding device in units of frame images. Frame image holding means for holding the frame image output by the output means as the second frame image in the next extraction of the second block;
It said extraction means according to claim 21, wherein the frame image holding means by utilizing the frame images are held as the second frame image, extracts the second block based on the block position data Decoding device. D / A conversion of the digital image data obtained in the pixel value addition means, D / A conversion means for converting to analog signals,
Noise addition means for adding analog noise, which is a noise component with respect to the analog component, to the analog signal obtained by D / A converting the digital image data by the D / A conversion means,
The decoding device according to claim 15 , wherein the decoding device outputs the analog signal to which the analog noise has been added by the noise adding means. A decoding method of a decoding device for decoding image data,
The first frame image that is the processing target frame image of the image data and the first block that is the processing target block among the blocks obtained by dividing the frame image into a plurality of regions. The first block of the second block, which is a block of a second frame image different from the first frame image, in which the sum of the absolute values of the pixel value differences in the specific pixel that is the position pixel is minimized. based on the block position data is relative position information for the block, an extraction step of extracting the second blocks from said second frame image,
A differential decoding step of decoding encoded data in which a pixel value difference is encoded between each pixel of the first block and each pixel of the second block to obtain a pixel value difference of each pixel ;
A discriminating step for discriminating a pixel value difference of the specific pixel from a pixel value difference of each pixel obtained by decoding the encoded data by the difference decoding step;
A difference setting step of setting a difference between pixel values of the specific pixels determined by the processing of the determination step to a predetermined value;
The difference of the difference setting pixel values of the specific pixel in which the predetermined value is set by the processing in step, and the difference of the pixel values of the pixels other than the specific pixel that has not been determined by the processing in the determining step, wherein A pixel value adding step of adding the pixel value of the second block extracted by the processing of the extraction step for each pixel to obtain the first block. A computer that decodes image data
The first frame image that is the processing target frame image of the image data and the first block that is the processing target block among the blocks obtained by dividing the frame image into a plurality of regions. The first block of the second block, which is a block of a second frame image different from the first frame image, in which the sum of the absolute values of the pixel value differences in the specific pixel that is the position pixel is minimized. based on the block position data is relative position information for the block, extracting means for extracting the second blocks from said second frame image,
Differential decoding means for decoding encoded data in which a pixel value difference is encoded between each pixel of the first block and each pixel of the second block, and obtaining a pixel value difference of each pixel ;
A discriminating unit for discriminating a pixel value difference of the specific pixel from a pixel value difference of each pixel obtained by decoding the encoded data by the difference decoding unit;
Difference setting means for setting a difference between pixel values of the specific pixels determined by the determination means to a predetermined value;
The extraction means extracts the difference between the pixel values of the specific pixels for which the predetermined value has been set by the difference setting means and the difference between the pixel values of the pixels other than the specific pixels that were not determined by the determination means. A computer-readable recording medium recorded with a program for adding pixel values to the pixel value of the second block for each pixel to function as pixel value adding means for obtaining the first block. A computer that decodes image data
The first frame image that is the processing target frame image of the image data and the first block that is the processing target block among the blocks obtained by dividing the frame image into a plurality of regions. The first block of the second block, which is a block of a second frame image different from the first frame image, in which the sum of the absolute values of the pixel value differences in the specific pixel that is the position pixel is minimized. based on the block position data is relative position information for the block, extracting means for extracting the second blocks from said second frame image,
Differential decoding means for decoding encoded data in which a pixel value difference is encoded between each pixel of the first block and each pixel of the second block, and obtaining a pixel value difference of each pixel ;
A discriminating unit for discriminating a pixel value difference of the specific pixel from a pixel value difference of each pixel obtained by decoding the encoded data by the difference decoding unit;
Difference setting means for setting a difference between pixel values of the specific pixels determined by the determination means to a predetermined value;
The extraction means extracts the difference between the pixel values of the specific pixels for which the predetermined value has been set by the difference setting means and the difference between the pixel values of the pixels other than the specific pixels that were not determined by the determination means. A program for adding pixel values to the pixel value of the second block for each pixel to function as pixel value adding means for obtaining the first block. In an information processing system that includes an encoding unit and a decoding unit, and the image data deteriorates when the encoding process and the decoding process are repeated on the image data,
The encoding unit includes:
Identification of a first frame image that is a processing target frame image of the image data that is a pixel at a predetermined position in the first block that is a processing target block in a block obtained by dividing the frame image into a plurality of regions pixel, a difference absolute value sum calculating means for calculating the sum of the absolute value of the difference of the specific pixel block of the first frame image and different from the second frame image,
Detecting means for detecting, as a second block, a block of the second frame in which the sum of the absolute values of the differences calculated by the difference absolute value sum calculating means is minimum ;
A difference calculating unit that calculates a difference between pixel values of pixels other than the specific pixel between the first block and the second block detected by the detecting unit;
Difference setting means for setting a difference between pixel values of the specific pixels to a predetermined value between the first block and the second block detected by the detection means;
Difference encoding means for encoding, for each block, a difference between pixel values of pixels other than the specific pixel calculated by the difference calculation means and a difference between pixel values of the specific pixels set by the difference setting means. An information processing system comprising: In an information processing system that includes an encoding unit and a decoding unit, and the image data deteriorates when the encoding process and the decoding process are repeated on the image data,
The decoding unit
The first frame image that is the processing target frame image of the image data and the first block that is the processing target block among the blocks obtained by dividing the frame image into a plurality of regions. The first block of the second block, which is a block of a second frame image different from the first frame image, in which the sum of the absolute values of the pixel value differences in the specific pixel that is the position pixel is minimized. based on the block position data is relative position information for the block, extracting means for extracting the second blocks from said second frame image,
Differential decoding means for decoding encoded data in which a pixel value difference is encoded between each pixel of the first block and each pixel of the second block, and obtaining a pixel value difference of each pixel ;
A discriminating unit for discriminating a pixel value difference of the specific pixel from a pixel value difference of each pixel obtained by decoding the encoded data by the difference decoding unit;
Difference setting means for setting a difference between pixel values of the specific pixels determined by the determination means to a predetermined value;
The extraction means extracts the difference between the pixel values of the specific pixels for which the predetermined value has been set by the difference setting means and the difference between the pixel values of the pixels other than the specific pixels that were not determined by the determination means. An information processing system comprising: pixel value addition means for adding the pixel value of the second block for each pixel to obtain the first block.

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