JP4793856B2 - Image scrambling device and image descrambling device - Google Patents

Description

  The present invention relates to an image scrambler and an image descrambler, and more particularly to an image scrambler suitable for scrambling and descrambling image data encoded by a predictive coding method.

  In a system that distributes still images and moving images via television broadcasting, the Internet, and the like, it is generally performed to scramble still images and moving images so that only a specific contractor can view them. In recent years, with the widespread use of digital content, in addition to the conventional scrambling of analog signals, Patent Document 1 proposes a technique for performing a scrambling process on a digital signal.

  On the other hand, digital image coding methods include intra-frame coding that uses the correlation between adjacent pixels in the target frame and inter-frame coding that uses the correlation between consecutive frames in the moving image. In recent years, techniques for improving the compression effect by skillfully combining intraframe coding and interframe coding have been studied. In addition, as a method for further improving the coding efficiency of intraframe coding, intraframe predictive coding in which predictive coding is performed based on the characteristics of adjacent blocks has been proposed.

In Patent Document 2, in intra-frame predictive coding of H.264 / AVC (Advanced Video Coding), which is one of the next-generation video coding systems, each frame is a block of 4 × 4 pixel size or 16 × 16 pixel size. (Macroblock) is divided into blocks, encoded for each block, a predicted image is generated using pixels adjacent to the target block to be encoded, and a difference value between the predicted image and the original image is converted. The compression efficiency is improved by quantizing. The prediction method used in intra-frame prediction is not one type, but nine types are prepared according to the prediction direction.
JP 2001-275111 A Japanese Patent Laid-Open No. 2005-252679

    The digital image is scrambled by performing predetermined data processing on the macroblock and changing the encoded data, and descrambling is performed by reversing the changed encoded data. .

  On the other hand, with respect to the scramble processing, there is a demand for performing the scramble processing only on a part of the image, as shown in an example in FIGS. However, a technique for scrambling only a part of an image in consideration of the influence of predictive coding in scrambling of predictive-coded image data has not been established yet. Even if only a part of the image can be scrambled, a technique for accurately canceling the scramble has not been established yet.

  An object of the present invention is to provide an image scramble / descramble apparatus that solves the above-described problems of the prior art and can selectively perform scramble / descramble only on a desired range of image data encoded by a prediction method. It is in.

According to the present invention, the following effects are achieved.
(1) According to the image scrambler of the present invention, since the predictive coding structure when the frame of the image data is predictively encoded is analyzed in units of macroblocks, the image data compressed by the predictive encoding method is used. Even in this case, only a desired part can be selectively scrambled.
(2) According to the image scramble apparatus of the present invention, the influence of the scramble to the desired scramble range outside the scramble range is analyzed, and the influence of the scramble outside the scramble range can be prevented. Even image data compressed by the method can be selectively scrambled in an arbitrary shape to only a desired portion.
(3) According to the image descrambling device of the present invention, since the prediction coding structure when the frame of the image data is predictively encoded is analyzed in units of macroblocks, the image data compressed by the prediction encoding method The scramble applied to a part of can be accurately canceled.
(4) According to the image descrambling device of the present invention, the influence of descrambling to the descrambling range is analyzed and the descrambling range is not affected by the descrambling range. Thus, it is possible to accurately cancel the scramble applied to a part of the image data compressed by the predictive encoding method in an arbitrary shape.
(5) According to the image scramble / descramble device of the present invention, the content of the scramble data processing (scramble key information) performed by the image scramble device is notified to the image descramble device. The descrambling can be performed easily and accurately based on the notified data processing content.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a functional block diagram showing the configuration of the main part of an image scrambler 1 according to the first embodiment of the present invention. When image data encoded and compressed by a predictive encoding method is input, it is scrambled. Scrambling is selectively executed within a predetermined range of a frame designated as a target and transferred to a subsequent processing system.

  In FIG. 1, a processing frame extraction unit 10 extracts a scramble target frame from image data and transfers it to an image storage unit 11 and a prediction analysis unit 12, and transfers a frame not to be scrambled to a subsequent processing system. The prediction analysis unit 12 analyzes the prediction encoding structure of the extracted frame, and analyzes the prediction direction when each block in the scramble range is predictively encoded as will be described in detail later. The analysis result is provided to the scramble processing unit 13. The scramble processing unit 13 scrambles some blocks in the scramble range based on the analysis result notified from the prediction analysis unit 12 so that the prediction affects all the blocks in the predetermined scramble range. The first data processing is executed.

  FIG. 2 is a flowchart showing a scramble procedure in the image scrambler 1. Here, for example, as in H.264 / AVC, a frame subjected to intraframe prediction encoding and a frame subjected to interframe prediction encoding are used. An example of scrambling of image data including

  In step S <b> 1, encoded data for one frame that has been predictively encoded is captured by the processing frame extraction unit 10. In step S2, the processing frame extraction unit 10 determines whether or not the frame is a scramble target frame. In the present embodiment, a frame subjected to intraframe prediction encoding is determined as a scramble target, and a frame subjected to interframe prediction encoding is determined not to be scrambled.

  If it is determined that the frame is a scramble target frame, the frame is transferred to the image storage unit 11 and the prediction analysis unit 12, and then the process proceeds to step S3. On the other hand, if it is determined that the frame is not scrambled, the process proceeds to step S6 described later. In step S 3, the scramble target frame is stored in the image storage unit 11. In step S4, the prediction analysis unit 12 analyzes the prediction coding structure of the frame.

  FIG. 3 is a diagram schematically illustrating an example of the analysis result of the prediction coding structure in the prediction analysis unit 12. In the intraframe prediction encoding method, pixel data is predictively encoded in units of macroblocks (MBij), and the prediction direction at that time is recorded for each MB. In the analysis result shown in FIG. 3, the prediction direction of all MBs is rightward. That is, among the pair of MBs adjacent to the left and right, the right MB is predictively encoded based on the predictive encoding data of the left MB, so the right MB is affected by the prediction of the left MB. . In step S5, scramble data processing (first data processing) is performed on some MB encoded data within the scramble range based on the analysis result of the predictive coding structure.

  FIG. 4 is a diagram schematically illustrating how a predetermined range is scrambled by rewriting a part of the MB encoded data sequence encoded by the intra-frame prediction method. The encoded data of each MB shown in (a) of the figure is converted into a differential value starting from the reference MB (MB0) to reduce the data amount, and the encoded data string shown in (b) of FIG. Is taken into the processing frame extraction unit 10 as follows.

  Here, if the prediction direction is rightward, when the first data processing for scramble is executed for any MB, the influence will affect all MBs located on the right side of the MB. Therefore, for example, if the range on the right side of MB4 is the scramble range 100, the scramble value X (“3” in the example of FIG. 4) is added to the encoded data of MB4 as shown in FIG. (First data processing), the encoded data is rewritten from “+2” to “+5”. Thereafter, when this encoded data string is decoded later, as shown in FIG. 4D, the influence of the scramble value X is spread to all MBs (MB4, MB5...) Located on the right side of MB4. Therefore, not only MB4 to which the scramble value X is added, but also MB5, MB6,... Can be scrambled.

  Therefore, if the scramble range 100 is set as shown in FIG. 5, all the data in the scramble range 100 can be obtained by simply performing the first data processing for scramble on the encoded data of MB22, MB32, and MB42. MB can be scrambled. If a frame encoded by the intra-frame prediction method is scrambled, other frames that are interframe prediction encoded based on the frame are similarly scrambled. All frames of data are scrambled.

  In the above-described embodiment, the case where the prediction direction of predictive encoding is rightward has been described as an example. However, the present invention is not limited to this, and the present invention is similarly applied to other prediction directions. it can.

  For example, if the prediction direction is downward as shown in FIG. 6, the first data processing for scramble is executed on three MBs (MB31, MB32, MB33) located at the upper end of the scramble range 100. All MBs in the scramble range 100 can be scrambled.

  Similarly, if the prediction direction is downward to the right as shown in FIG. 7, seven MBs (MB22, MB32, MB42, MB52, MB23, MB24, MB25) located at the upper and left ends of the scramble range 100 are used. If the first data processing for scramble is executed in (), all MBs in the scramble range 100 can be scrambled.

  As described above, according to the present embodiment, since the predictive coding structure when the frame of the image data is predictively encoded is analyzed in units of macroblocks, the image data is compressed by the predictive encoding method. However, it is possible to selectively scramble only a desired part.

  By the way, in the image scramble, as shown in FIG. 8 as an example, there is a demand for performing a scramble process on an arbitrary part of an image in a frame shape. However, in the intraframe predictive coding method, as described with reference to FIG. 4 (d), when the scramble data processing is executed on one MB, the influence is exerted on all MBs in the prediction direction. It reaches. Therefore, in the first embodiment described above, although partial scrambling as shown in FIG. 9 is possible according to the prediction direction, scrambling cannot be performed in a frame shape as shown in FIG. On the other hand, in the embodiment described below, such frame-like scrambling is possible.

  FIG. 10 is a functional block diagram of a scrambler according to the second embodiment of the present invention. The same reference numerals as those described above represent the same or equivalent parts.

  The processing frame extraction unit 10 extracts a scramble target frame and transfers it to the image storage unit 11 and the prediction analysis unit 12, and transfers the non-scramble frame to the subsequent processing system. The prediction analysis unit 12 analyzes the prediction encoding structure of the extracted frame, and provides the analysis result to the scramble processing unit 13 and the influence elimination unit 14. The scramble processing unit 13 executes a first data process for scrambling only a partial range of the extracted frame based on the analysis result notified from the prediction analysis unit 12. Based on the analysis result notified from the prediction analysis unit 12 and the content of the first data processing, the influence analysis unit 15 is applied to only a part of the range when the image data is decoded later. Analyze the effect of scrambling on other areas. The influence eliminating unit 14 executes second data processing for eliminating the influence on the other area based on the influence analysis result.

  FIG. 11 is a flowchart showing a scramble procedure in the image scramble apparatus 2. Here, for example, as in H.264 / AVC, a frame subjected to intraframe prediction encoding and a frame subjected to interframe prediction encoding are used. An example of scrambling of image data including

  In step S <b> 11, encoded data for one frame that has been predictively encoded is taken into the processing frame extraction unit 10. In step S12, the processing frame extraction unit 10 determines whether or not the frame is a scramble target frame. In the present embodiment, a frame subjected to intraframe prediction encoding is determined as a scramble target, and a frame subjected to interframe prediction encoding is determined not to be scrambled.

  If it is determined that the frame is to be scrambled, the frame is transferred to the image storage unit 11 and the prediction analysis unit 12, and then the process proceeds to step S13. On the other hand, if it is determined that the frame is not scrambled, the process proceeds to step S18 described later. In step S <b> 13, the scramble target frame is stored in the image storage unit 11. In step S14, the prediction analysis unit 12 analyzes the prediction coding structure of the frame. In the present embodiment, an example will be described in which the prediction directions of all MBs are rightward as indicated by arrows in FIG.

  In step S15 and subsequent steps, scrambling is performed only within a desired range by performing data processing for scrambling on some MBs within the scramble range based on the analysis result of the predictive coding structure. Here, the procedure after step S15 will be schematically described first with reference to FIG.

  FIG. 12 is a diagram schematically showing how a predetermined area is scrambled by rewriting a part of an MB data sequence encoded and compressed by the intra-frame prediction method. The encoded data of each MB shown in (a) of the figure is converted into a differential value starting from the reference MB (MB0) to reduce the data amount, and the encoded data string shown in (b) of FIG. Is taken into the processing frame extraction unit 10. If the range from MB4 to MB7 is the scramble range 100, the first data processing is performed on the encoded data of MB4 as shown in FIG. As a result, the scramble value X (“3” in the example of FIG. 12) is added to the encoded data of MB4, and the value is rewritten from “+2” to “+5”.

  However, when the scrambled encoded data sequence in FIG. 12C is decoded later, the influence of the scramble value X is affected by the MB4 in the scramble range 100 as shown in FIG. It extends to not only MB7 but also MB8 after MB8 outside the scramble range. As a result, the encoded data of MB8 is rewritten from the original “129” to “132”, and the encoded data of MB9 is rewritten from the original “128” to “131”.

  Therefore, in the present embodiment, as shown in FIG. 5E, if the prediction direction is rightward, the second data processing is performed on the encoded data of MB8 adjacent to the right side of the scramble range 100, and the MB8 The scramble value X is subtracted from the encoded data. As a result, when this encoded data string is decoded, only MB (MB4 to MB7) in the scramble range 100 is rewritten and scrambled as shown in FIG. Normal encoded data not subjected to is obtained.

  Returning to FIG. 11, in step S15, scrambling is performed on a predetermined area by rewriting the encoded data of a part of the MB stored in the image storage unit 11. This corresponds to the procedure shown in FIG. 12 (c). In this embodiment, since the scramble range 100 is set as shown in FIG. 13, the three positions located at the left end of the area 100 are set. For MB (MB22, MB32, MB42), the encoded data is rewritten in the same manner according to the scramble value X.

  Step S16 corresponds to the procedure (d) of FIG. 12, and the influence analysis unit 15 affects the influence of the scramble outside the scramble range based on the analysis result of the predictive coding structure and the content of the scramble process. Analyzed. FIG. 14 is a diagram schematically showing the analysis method in the influence analysis unit 15, and if the prediction direction of each MB is rightward as in the present embodiment, the scramble adjacent to the right side of the original scramble range 100 is shown. It is recognized that each MB outside the range (MB25, MB35, MB45) is also affected by scrambling.

  Step S17 corresponds to the procedure shown in FIG. 12 (e). Based on the result of the influence analysis, the effect removal unit 14 executes three MBs (in which the second data processing is executed in order to eliminate the influence). MB25, MB35, MB45) are selected and the second data processing is executed, and the scramble value X is subtracted from each value. In step S18, the encoded data is transferred to the subsequent processing system.

  In the above-described embodiment, the case where the prediction direction of predictive encoding is rightward has been described as an example. However, the present invention is not limited to this, and the present invention is similarly applied to other prediction directions. it can.

  For example, if the prediction direction is downward as shown in FIG. 15, the first data processing for scrambling is executed on three MBs (MB22, MB23, MB24) located at the upper end of the scramble range 100. The scramble value X is added. Further, the second data processing is executed on three MBs (MB52, MB53, MB54) outside the scramble range adjacent to the lower side of the scramble range 100, and the scramble value X is reduced.

  Similarly, if the prediction direction is downward to the right as shown in FIG. 16, it is used for scrambling into 5 MBs (MB22, MB32, MB42, MB23, MB24) located at the upper and left ends of the scramble range 100. The first data processing is executed and the scramble value X is added. Further, the second data processing is performed on five MBs (MB34, MB45, MB52, MB53, MB54) outside the scramble range adjacent to the lower right of the scramble range 100, and the scramble value X is reduced.

  Furthermore, even when the prediction direction is set for each MB as shown in FIG. 17, if the prediction direction of each MB and the scramble range 100 are known, the first data processing is executed and the scramble value X is added. MB22 and MB52, MB53, and MB25 in which the second data processing is executed and the scramble value X is decreased are determined.

  According to the present embodiment, the influence of the scramble to the desired scramble range outside the scramble range is analyzed, and the influence of the scramble outside the scramble range can be prevented. Even for data, only a desired part can be selectively scrambled in an arbitrary shape.

  Next, the operation of the scrambler according to the third embodiment of the present invention will be described with reference to the flowchart of FIG. In the present embodiment, description will be given by taking scramble of image data encoded and compressed by the MPEG-2 system as an example.

  In step S <b> 11, encoded data for one frame of the predictive-encoded image data is taken into the processing frame extraction unit 10. In step S12, the processing frame extraction unit 10 determines whether or not the frame is a scramble target frame.

  In this embodiment, if the frame is an I frame (Intra-coded Frame), it is determined as a frame to be scrambled, transferred to the image storage unit 11 and the prediction analysis unit 12, and the process proceeds to step S13. If it is any other P frame (Predicted Frame) or B frame (Bi-directional Predicted Frame), it is determined that the frame is not scrambled, and the process proceeds to step S18. In step S13, the I-frame to be scrambled is stored in the image storage unit 11. In step S14, the prediction analysis unit 12 analyzes the bit stream information of the I frame, and acquires information on the propagation direction and propagation range of the DC prediction from the slice information in the I frame.

  FIG. 18 is a diagram schematically representing an analysis result by the prediction analysis unit 12. In the present embodiment, the frame is divided in units of macroblocks (MB), and slices 21 (21a to 21i) are configured from a plurality of MBs. In MPEG-2, the direction of the influence of the prediction is the right direction, and the influence of the prediction does not reach the outside of the slice 21. The prediction result is transferred from the prediction analysis unit 12 to the scramble processing unit 13 and the influence elimination unit 14.

  In step S15, a predetermined area of the I frame stored in the image storage unit 11 is scrambled. In MPEG-2, each MB is composed of blocks of luminance and color difference, and if the format is 4: 2: 0, as shown in FIG. 19, four luminance blocks Y1, Y2, Y3, It is composed of Y4 and two color difference blocks Cb and Cr. Here, if the scramble process is a process of decreasing (or increasing) the value of the DC component of the luminance block Y1 by 10, a data sequence in which only the DC component of the luminance block is arranged in one column is described with reference to FIG. Similar processing is executed by regarding the data string as described.

  FIG. 20 shows the positional relationship between the MB on which the scramble data process (first data process) is executed and the MB on which the data process (second data process) for eliminating the influence of the scramble is executed in the present embodiment. FIG.

  For the three MB22, MB32, and MB42 at the left end of the scramble range 100, the encoded data is subjected to the first data processing for scramble. The two MB33 and MB34 in the scramble range located on the right side of MB32 belong to the same slice 21e as MB32, and the encoded data is automatically rewritten under the influence of prediction from MB32. 1 Data processing is not performed. Similarly, since the two MB43 and MB44 within the scramble range located on the right side of MB42 belong to the same slice 21g as MB42, the first data processing is not performed here.

  On the other hand, the MB23 located on the right side of the MB22 belongs to a slice 21d different from the slice 21c to which the MB22 belongs, and is not affected by the prediction from the MB22, so the first data processing for scramble is executed. Is done. Since the MB 24 adjacent to the right side of the MB 23 belongs to the same slice 21d as the MB 23 and is affected by the prediction from within the MB 23, the first data processing is not performed here.

  Returning to FIG. 11, in step S <b> 16, the influence analysis unit 15 analyzes the influence of the scramble outside the scramble range based on the analysis result of the predictive coding structure and the content of the scramble process.

  In the present embodiment, as shown in FIG. 20, among the six MBs outside the scramble range located on the right side of the scramble range 100, MB25 and MB26 belong to the same slice 21d as the MB24 in the scramble region 100. Since the data is scrambled under the influence of the prediction, the second data processing is executed on the encoded data of MB25. Similarly, since MB35 and MB36 belong to the same slice 21e as MB34 in the scramble range 20, the second data processing is executed on the encoded data of MB35. On the other hand, MB45 and MB46 belong to a different slice 21h from MB44 within the scramble range, and are not affected by the prediction, so the second data processing is not performed.

  According to the present embodiment, it is possible to selectively scramble only a part of the image data compressed by the MPEG-2 system.

  FIG. 21 is a functional block diagram of the scrambler 4 according to the fourth embodiment of the present invention. The same reference numerals as those described above represent the same or equivalent parts.

  In the present embodiment, the processing content of the first data processing executed by the scramble processing unit 13 is registered in the image data as scramble key information in the configuration of the first embodiment described with reference to FIG. 1 and transmitted to the descrambling device. The key information notifying unit 16 is characterized. The key information notification unit 16 embeds the key information in the image data as a digital watermark or registers it in the header portion of the image data.

  According to the present embodiment, the descrambling device for descrambling the image data transmitted from the scrambler 4 correctly performs descrambling without using a means for analyzing the predictive coding structure, as will be described in detail later. Will be able to run.

  FIG. 22 is a functional block diagram of the scrambler 5 according to the fifth embodiment of the present invention. The same reference numerals as those described above represent the same or equivalent parts.

  In the present embodiment, the contents of the first data processing executed by the scramble processing unit 13 and the second data processing executed by the influence eliminating unit 14 are added to the configurations of the second and third embodiments described with reference to FIG. It is characterized in that a key information notifying unit 17 is provided for registering processing contents in image data as scramble key information and transmitting it to the descrambling device. Also in this embodiment, the key information notification unit 17 embeds the key information in the image data as a digital watermark or registers it in the header portion of the image data.

  According to the present embodiment, the descrambling device for releasing the scramble of the image data transmitted from the scrambler 5 is a unit for analyzing the prediction coding structure and a unit for analyzing the influence of the prediction, as will be described in detail later. Descrambling can be executed accurately without using.

  In the above embodiment, the case where the rectangular scramble range is set only at one place has been described as an example. However, as shown in FIG. 23, the first data processing for scramble (marked with ○ in the figure). ) And the second data processing for eliminating the effect (indicated by ◇ in the figure), the scramble range 100 may be circular as shown in (a) of the figure, or as shown in (b) of the figure. Can be set at multiple locations.

  Further, in each of the above-described embodiments, it has been described that the first data processing for scrambling and the second data processing for canceling the effect add or subtract a predetermined scrambling value to the encoded data of each MB. The present invention is not limited to this, and can be similarly applied to other scrambling methods in which the arrangement of encoded data is replaced or a predetermined function operation is performed on the encoded data.

  Furthermore, in each of the above-described embodiments, it has been described that the first data processing for scrambling is performed only once at the end of the scramble range, and the second data processing for effect elimination is performed only once. If the scramble value is constant within the scramble range, the relationship between the scrambled image and the current image becomes constant, and the image of the current image may remain in the scrambled image.

  On the other hand, as shown in FIG. 34, if the first data processing is performed in a plurality of times in the scramble range 100, the influence of the current image on the scrambled image can be reduced, Its readability can be reduced.

  FIGS. 35 and 36 are diagrams showing an example of the scramble method when the first data processing is performed in a plurality of times in the scramble range 100. FIG. In either figure, the encoded data of each MB shown in (a) of the figure is converted into a differential value starting from the reference MB (MB0) to reduce the amount of data, and shown in (b) of the figure. The processed frame extraction unit 10 takes in the encoded data string.

  35, if MB2 to MB7 are in the scramble range 100, as shown in FIG. 35C, the first first data processing is performed on the encoded data of MB2, and the scramble value X1 (example in FIG. 35) Then, “7”) is added, and the encoded data is rewritten from “+2” to “+9”. Further, the first data processing of the second time is performed on the encoded data of MB3, and the scramble value X2 (“5” in the example of FIG. 35) is added, and the encoded data is changed from “−1” to “+4”. To be rewritten. Further, the first data processing for the third time is performed on the encoded data of MB6, and the scramble value X3 (“−5” in the example of FIG. 35) is added, and the encoded data is changed from “−5” to “−”. 10 ". Then, the second data processing is performed on the encoded data of MB8 and a scramble value X4 (“−7” in the example of FIG. 35) is added, and the encoded data is changed from “−4” to “−11”. Rewritten.

  Similarly, in FIG. 36, if MB2 to MB7 are in the scramble range 100, as shown in FIG. 36C, the first first data processing is performed on the encoded data of MB2, and the scramble value X1 (FIG. In the example of 36, “8”) is added, and the encoded data is rewritten from “+2” to “+10”. Further, the first data processing of the second time is performed on the encoded data of MB4 and a scramble value X2 (“−5” in the example of FIG. 36) is added, and the encoded data is changed from “+2” to “−3”. Will be rewritten. Further, the third first data processing is performed on the encoded data of MB7 and the scramble value X3 (“+10” in the example of FIG. 36) is added, and the encoded data is changed from “+6” to “+16”. Rewritten. Then, the second data processing is performed on the encoded data of MB8, and the scramble value X4 (“−13” in the example of FIG. 36) is added, and the encoded data is changed from “−4” to “−17”. Rewritten.

  As described above, even when the first data processing is performed in a plurality of times, the total sum of the scramble values (X1 + X2 + X3) in the first data processing and the scramble values X4 in the second data processing is “0”. As a result, only the desired scramble range 100 can be scrambled.

  FIG. 24 is a functional block diagram showing the configuration of the main part of the descrambling device 6 according to the sixth embodiment of the present invention, which is scrambled by the scrambling device 1 of the first embodiment described with reference to FIG. This is a descrambling apparatus suitable for descrambling image data.

  The processing frame extraction unit 30 extracts the scrambled frame and transfers it to the image storage unit 31 and the prediction analysis unit 32, and the unscrambled frame is subjected to variable length decoding connected to the subsequent stage. The data is transferred to a decoding processing system including a conversion unit, an inverse quantization unit, an inverse orthogonal transform unit, and the like. The prediction analysis unit 32 analyzes the prediction coding structure of the extracted frame and provides the analysis result to the descrambling processing unit 33. The descrambling processing unit 33 performs data processing (third data processing) for releasing the scramble of the extracted frame based on the analysis result notified from the prediction analysis unit 32.

  FIG. 25 is a flowchart showing a descrambling procedure in the image descrambling device 6. In step S31, the scrambled encoded data for one frame is taken into the processing frame extraction unit 30. In step S32, the processing frame extraction unit 30 determines whether or not the frame is a descramble target frame. The frame determined to be descrambled is transferred to the image storage unit 31, and the process proceeds to step S33. If it is determined not to be descrambled, the process proceeds to step S38.

  In step S <b> 33, the descramble target frame is stored in the image storage unit 31. In step S34, the prediction analysis unit 12 analyzes the prediction coding structure of the frame. In step S35 and subsequent steps, data processing (third data processing) for canceling scrambling applied to a predetermined range of the frame stored in the image storage unit 31 is executed. Here, first, the procedure after step S35 will be schematically described with reference to FIG.

  FIG. 26 is a diagram schematically showing a procedure for descrambling descrambling applied to a part of image data encoded by the intra-frame prediction method.

  The encoded data sequence shown in FIG. 6A is converted into the data sequence shown in FIG. 5B through the same data processing as in the first embodiment. This data sequence is the same as the data sequence shown in FIG. 4 (c), and data processing is performed in which MB4 and all MBs located in the right direction thereof are scrambled.

  In order to descramble this data string, as shown in FIG. 26 (c), data processing (third process) in which the descramble value X (“3” in the present embodiment) is subtracted from the encoded data of MB4. Data processing) may be executed. As a result, when this encoded data string is decoded later, the influence of the descrambling value X extends to all MBs located in the right direction of MB4 as shown in FIG. become.

  Returning to FIG. 25, in step S35, descrambling is performed in a predetermined area by executing third data processing for descrambling on some MBs of the frame stored in the image storage unit 31. This corresponds to the procedure of FIG. 26 (c). In this embodiment, since the scramble range 100 described with reference to FIG. 5 is a descramble range, three MBs ( The third data processing for descrambling is executed on the encoded data of MB22, MB32, MB42). That is, the descrambling value X (“3” in the present embodiment) is reduced. In step S38, the descrambled frame is transferred to the subsequent decoding processing system.

  According to the present embodiment, since the predictive coding structure when the frame of the image data is predictively encoded is analyzed in units of macroblocks, the scramble applied to a part of the image data compressed by the predictive encoding method Can be canceled correctly.

  FIG. 27 is a functional block diagram showing the configuration of the main part of the descrambling device 7 according to the seventh embodiment of the present invention. The scrambling device 2 of the second and third embodiments described with reference to FIG. This is a descrambling apparatus suitable for descrambling the converted image data.

  The processing frame extraction unit 30 extracts the scrambled frame and transfers it to the image storage unit 31 and the prediction analysis unit 32, and transfers the unscrambled frame to a subsequent decoding processing system. . The prediction analysis unit 32 analyzes the prediction encoding structure of the extracted frame, and provides the analysis result to the descrambling processing unit 33 and the influence elimination unit 34. The descrambling processing unit 33 performs data processing (third data processing) for releasing the scramble of the extracted frame based on the analysis result notified from the prediction analysis unit 32.

  The influence analysis unit 35 analyzes the influence of the current descrambling out of the scramble range based on the analysis result notified from the prediction analysis unit 32 and the data processing content of the descrambling. The influence eliminating unit 34 performs data processing (fourth data processing) for eliminating the influence of descrambling outside the scramble range on the extracted frame based on the influence analysis result.

  FIG. 28 is a flowchart showing a descrambling procedure in the image descrambling device 7. Here, descrambling of image data subjected to intraframe prediction coding will be described as an example.

  In step S <b> 31, encoded data for one frame that has been predictively encoded is taken into the processing frame extraction unit 30. In step S32, the processing frame extraction unit 30 determines whether or not the frame is a descramble target frame. The frame determined to be descrambled is transferred to the image storage unit 31 and the prediction analysis unit 32, and the process proceeds to step S33. If it is determined not to be descrambled, the process proceeds to step S38.

  In step S <b> 33, the descramble target frame is stored in the image storage unit 31. In step S34, the prediction analysis unit 12 analyzes the prediction coding structure of the frame. In step S35 and subsequent steps, data processing (third data processing) for releasing scramble applied to a partial area of the frame stored in the image storage unit 31 is executed. Here, the procedure after step S35 will be schematically described first with reference to FIG.

  FIG. 29 is a diagram schematically showing a procedure for releasing the scramble of a frame that has been encoded in advance using the intra-frame prediction method and scrambled only in part.

  The encoded data sequence shown in FIG. 9A is encoded and compressed in advance and converted to the data sequence shown in FIG. This data string is the same as the data string shown in FIG. 12 (e), and data processing is performed in which MB4 to MB7 are scrambled.

  In order to descramble this data string, as shown in FIG. 29 (c), data processing (third process) in which the descramble value X (“3” in the present embodiment) is subtracted from the encoded data of MB4. Data processing) may be performed. However, when this encoded data string is decoded later, the influence of the descrambling value X is not only in the scramble range MB4 to MB7 but also outside the scramble range, as shown in FIG. It extends to MB8 and MB9. As a result, the encoded data of MB8 is changed from the original “129” to “126”, and the encoded data of MB9 is changed from the original “128” to “125”.

  Therefore, in the present embodiment, as shown in FIG. 4E, if the prediction direction is rightward, the descrambling value X is added to the encoded data of MB8 adjacent to the right side of the scramble range. As a result, when this encoded data sequence is decoded, only the encoded data in the descrambling range 200 is rewritten as shown in FIG. Can be obtained.

  Returning to FIG. 28, in step S35, the third data processing for descrambling is executed on the frame stored in the image storage unit 31. This corresponds to the procedure shown in FIG. In the present embodiment, since the descrambling range 200 is set as shown in FIG. 30, three MBs (MB22, MB32, MB42) located at the left end of the region 200 are scrambled. Third data processing is executed.

  Step S36 corresponds to the procedure of FIG. 29 (d), and the influence analysis unit 35 causes the descrambling to be out of the scramble range based on the analysis result of the predictive coding structure and the descrambling processing content. Impact is analyzed. FIG. 30 is a diagram schematically showing an analysis method in the influence analysis unit 15. If the prediction direction of each MB is rightward as in this embodiment, it is adjacent to the right side of the original descrambling range 200. It is recognized that descrambling affects each MB (MB25, MB35, MB45) outside the descrambling range.

  Step S37 corresponds to the procedure of FIG. 29 (e), and three MBs shown in FIG. 31 are shown as MBs on which the fourth data processing is executed in order to eliminate the influences based on the influence analysis results. (MB25, MB35, MB45) is selected and the scramble value X is decreased. In step S38, the encoded data is transferred to the subsequent processing system.

  According to the present embodiment, the influence of descrambling to the descrambling range outside the descrambling range is analyzed, and it is possible to prevent the descrambling from affecting the descrambling range. Thus, it is possible to accurately cancel the scramble applied to a part of the processed image data in an arbitrary shape.

  FIG. 32 is a functional block diagram showing the configuration of the main part of the descrambling device 8 according to the eighth embodiment of the present invention, which is scrambled by the scrambling device 4 of the fourth embodiment described with reference to FIG. This is a descrambling apparatus suitable for descrambling image data.

  In the present embodiment, instead of the prediction analysis unit 32 described with reference to FIG. 24, key information related to the scramble condition is extracted from the image data, and based on the key information, the descramble processing unit 33 performs the third data processing. There is a feature in that a descrambling condition determining unit 39 for executing the above is provided.

  According to the present embodiment, the descrambling device 8 can recognize the MB to be subjected to the third data processing for descrambling based on the key information related to the scramble, and thus is necessary in the above-described seventh embodiment. The prediction analysis unit 32 becomes unnecessary.

  FIG. 33 is a functional block diagram showing the configuration of the main part of the descrambling device 9 according to the ninth embodiment of the present invention, which is scrambled by the scrambling device 5 of the fifth embodiment described with reference to FIG. This is a descrambling apparatus suitable for descrambling image data.

  In the present embodiment, instead of the prediction analysis unit 32 and the influence analysis unit 35 described with reference to FIG. 27, key information related to the scramble condition is extracted from the image data, and based on the key information, the descrambling processing unit 33 and The influence eliminating unit 34 is characterized in that a descrambling condition determining unit 40 for executing the third data processing and the fourth data processing is provided.

  According to the present embodiment, the descrambling device 9 can recognize the MB to be subjected to the third data processing for descrambling and the fourth data processing for effect cancellation based on the key information related to scrambling. The prediction analysis part 32 and the influence analysis part 35 which were necessary in 7th Embodiment become unnecessary.

  In the eighth and ninth embodiments, the key information is extracted from the image data. However, the present invention is not limited to this, and is indicated by a wavy arrow in FIGS. As described above, the descrambling apparatus may be notified through a route different from that of the data image by using an appropriate communication unit or the like.

1 is a functional block diagram showing a configuration of a main part of an image scrambler 1 according to a first embodiment of the present invention. 2 is a flowchart showing a scramble procedure by the image scramble apparatus in FIG. FIG. 6 is a diagram schematically illustrating an example of an analysis result of a predictive coding structure in the first embodiment. It is the figure which showed typically a mode that a predetermined range was scrambled by rewriting a part of data sequence encoded with the intra-frame prediction system. It is the figure which showed the identification method of the macroblock (MB) processed in order to scramble a predetermined scramble range. It is the figure which showed the identification method of the macroblock (MB) in which the data process for scramble is performed when a prediction direction is downward. It is the figure which showed the identification method of the macroblock (MB) in which the data process for scramble is performed when a prediction direction is a lower right direction. It is FIG. (1) for demonstrating the subject of 1st Embodiment. It is FIG. (2) for demonstrating the subject of 1st Embodiment. It is a functional block diagram of the scramble apparatus which concerns on 2nd Embodiment of this invention. 11 is a flowchart showing a scramble procedure in the image scramble apparatus of FIG. 10. It is the figure which showed typically a mode that a predetermined range was scrambled by rewriting a part of data sequence encoded with the intra-frame prediction system. It is the figure which showed the identification method of the macroblock (MB) processed in order to scramble a predetermined scramble range. It is the figure which showed typically the method of analyzing the influence which a scramble has outside a scramble range. It is the figure which showed the identification method of the macroblock (MB) in which the data process for a scramble / descramble is performed when a prediction direction is downward. It is the figure which showed the identification method of the macroblock (MB) in which the data process for a scramble / descramble is performed when a prediction direction is a lower right direction. It is the figure which showed the identification method of the macroblock (MB) in which the data process for a scramble / descramble is performed when a prediction direction is set for every MB. It is the figure which expressed typically an example of the analysis result of the prediction coding structure in a 2nd embodiment. It is the figure which showed the scramble method in MPEG-2. It is the figure which showed the positional relationship of MB with which the 1st data process for scramble is performed, and MB with which the 2nd data process for descrambling is performed in 3rd Embodiment. It is the functional block diagram which showed the structure of the principal part of the image scramble apparatus which concerns on 4th Embodiment of this invention. It is the functional block diagram which showed the structure of the principal part of the image scramble apparatus which concerns on 5th Embodiment of this invention. It is the figure which showed the example of a setting of the scramble range. It is the functional block diagram which showed the structure of the principal part of the descrambling apparatus which concerns on 6th Embodiment of this invention. It is the flowchart which showed the descrambling procedure by the image descrambling apparatus of FIG. It is the figure which showed typically the descrambling procedure which cancels | releases the scramble performed to the part of the image data encoded with the intra-frame prediction system. It is the functional block diagram which showed the structure of the principal part of the descrambling apparatus which concerns on 7th Embodiment of this invention. It is the flowchart which showed the descrambling procedure by the image descrambling apparatus of FIG. It is the figure which showed typically the descrambling procedure which cancels | releases the scramble performed to the part of the image data encoded with the intra-frame prediction system. It is the figure which showed the identification method of the macroblock (MB) in which the 3rd data process for descrambling is performed when a prediction direction is horizontal. It is the figure which showed the identification method of the macroblock (MB) in which the 4th data process for eliminating the influence of a descrambling when a prediction direction is horizontal is performed. It is the functional block diagram which showed the structure of the principal part of the image descrambling apparatus which concerns on 8th Embodiment of this invention. It is the functional block diagram which showed the structure of the principal part of the image descrambling apparatus which concerns on 9th Embodiment of this invention. It is the figure which showed the Example which divides | segments the 1st data process for scramble into multiple times. FIG. 5 is a diagram (part 1) schematically illustrating a descrambling procedure in which the first data processing for scrambling is divided into a plurality of times. FIG. 9 is a diagram (part 2) schematically showing a descrambling procedure for dividing the first data processing for scrambling into a plurality of times.

Claims (11)

In an image scramble apparatus that scrambles a predetermined area of image data in which each frame is predictively encoded in units of blocks,
Processing frame extraction means for extracting frames to be scrambled;
A prediction analysis means for analyzing a prediction coding structure including a prediction direction when each block is sequentially intraframe prediction coded with reference to adjacent blocks in the extracted frame;
Scramble processing means for executing first data processing for scrambling on some blocks within a predetermined scramble range based on the analysis result of the predictive coding structure ;
The scramble processing means outputs the encoded data to a part of blocks that are the start point of the prediction direction within the scramble range so that all the blocks within the scramble range are affected by the first data processing. An image scrambler that executes first data processing for scramble rewriting . Based on the analysis result by the predictive analysis means, and impact analysis means for first data processing for the scrambling to analyze the effects of the encoded data is rewritten in the scrambling range及Nde outside the scramble range outside blocks,
Based on the result of the influence analysis, comprising an influence eliminating means for executing a second data process for eliminating the influence outside the scramble range on the extracted frame ,
The influence canceling means changes the encoded data changed due to the influence of the rewrite of the encoded data of a part of the blocks as the start point by the first data processing, and the encoded data of the part of the blocks as the start point 2. The image scramble apparatus according to claim 1 , wherein the value is returned to a value when it is not rewritten . The image data includes a frame encoded by an intra-frame predictive encoding scheme and a frame encoded by an inter-frame predictive encoding scheme, and the processing frame extracting means is encoded by an intra-frame predictive encoding scheme 3. The image scramble apparatus according to claim 1, wherein a frame is extracted. 3. The image scramble apparatus according to claim 1, wherein the image data is encoded by an MPEG-2 system, and the processing frame extraction unit extracts an I frame. As the key information for the scrambling, the image scrambling apparatus according to any one of claims 1 to 4, further comprising a key information output means for outputting the contents of said first data processing. As the key information for the scrambling, the image scrambling apparatus according to any one of claims 1 to 4, further comprising a key information output means for outputting the contents of said first and second data processing. 7. The image scramble apparatus according to claim 5, wherein the key information output unit embeds the scramble key information as an electronic watermark in the image data and outputs the image data. 7. The image scramble apparatus according to claim 5, wherein the key information output means writes the scramble key information in a header portion of image data and outputs the same. In an image descrambling device for releasing scrambling applied to a predetermined area of image data in which each frame is predictively encoded in units of blocks
Processing frame extracting means for extracting descrambled frames;
A prediction analysis means for analyzing a prediction coding structure including a prediction direction when each block is sequentially intraframe prediction coded with reference to adjacent blocks in the extracted frame;
Key information obtaining means for obtaining the scramble key information;
Descramble processing means for executing third data processing for descrambling on some blocks within a predetermined descrambling range based on the analysis result of the predictive coding structure and key information ,
The descrambling processing means applies the code to a part of blocks that are the starting point of the prediction direction in the descrambling range so that all the blocks in the descrambling range are affected by the third data processing. Execute the third data processing for descrambling to rewrite the data,
The processing frame extraction means encodes the image data using an intra-frame predictive encoding method if the image data includes a frame encoded using an intra-frame predictive encoding method and a frame encoded using an inter-frame predictive encoding method. An image descrambling device that extracts a frame and extracts an I frame if the frame is encoded by the MPEG-2 system . On the basis of the analysis result of the predictive analysis means, third data processing impact analysis means for analyzing the effects of the encoded data is rewritten in the Nde及to descramble range outside the descramble range block for the descrambling When,
Based on the influence analysis result and the key information , including an influence elimination means for executing a fourth data process for eliminating the influence outside the descrambling range on the extracted frame ,
The influence canceling means changes the encoded data changed by the influence of rewriting the encoded data of a part of the blocks as the start point by the third data processing, and the encoded data of the part of the blocks as the start point. The image scrambler according to claim 9 , wherein the value is returned to a value when it is not rewritten . The image descrambling apparatus according to claim 9 or 10 , wherein the key information acquisition unit extracts the key information from image data.

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