JP6150912B2 - Image encoding device, image encoding method and program, image decoding device, image decoding method and program - Google Patents

Description

  The present invention relates to an image encoding device, an image encoding method and program, an image decoding device, an image decoding method and a program, and more particularly to a predictive encoding method of a quantization parameter in an image.

  As a method for compressing and recording a moving image, H.264 is used. H.264 / MPEG-4 AVC (hereinafter referred to as H.264) is known (Non-Patent Document 1). H. H.264 is widely used in one-segment terrestrial digital broadcasting.

H. In H.264, the quantization parameter can be changed in units of macroblocks (16 pixels × 16 pixels) using the mb_qp_delta code. According to Equation 7-23 described in Non-Patent Document 1, a macroblock (16 pixels × 16 pixels) is obtained by adding the difference value mb_qp_delta to the quantization parameter QPY _PREV of the macroblock decoded immediately before. ) The quantization parameter is changed in units.

  In recent years, H.C. As a successor to H.264, activities for international standardization of HEVC (High Efficiency Video Coding), which is a more efficient coding method, have started. In this activity, division with a larger block size than the conventional macroblock (16 pixels × 16 pixels) is considered as the target screen size increases. According to Non-Patent Document 2, this large-sized basic block is called LCTB (Large Coding Tree Block). The size is studied as 64 pixels × 64 pixels (Non-Patent Document 2). The LCTB is further divided to form fine sub-blocks and divided into CTBs (Conding Tree Blocks) as sub-blocks for performing transformation, quantization, and the like. As a division method, an area quadtree structure in which a block is divided into two vertically and horizontally is used.

  FIG. 2A shows the state of the area quadtree structure. A thick frame 10000 represents a basic block, and has a configuration of 64 pixels × 64 pixels in order to simplify the description. Reference numerals 10001 and 10010 denote sub-blocks, which are 16 pixel × 16 pixel sub-blocks. Reference numerals 10002 to 10009 are also sub-blocks, and are 8 pixel × 8 pixel sub-blocks. In this way, it is divided finely and an encoding process such as conversion is performed.

ISO / IEC 14496-10; 2004 Information technology-Coding of audio-visual objects-Part 10: Advanced Video Coding JCT-VC contribution JCTVC-A205. doc <http: // wftp3. itu. int / av-arch / jctvc-site / 2010_04_A_Dresden />

  In HEVC, the quantization parameter is controlled by H.264. Similar to the H.264 macroblock, it is considered to perform the basic block unit. However, in practice, it is desirable from the viewpoint of image quality to perform quantization parameter control in units of sub-blocks. In this case, it can be expected that quantization in finer units can be performed by performing quantization parameter control in subblock units.

  However, even if quantization can be performed in finer units, processing is performed according to the area quadtree structure, so parallel processing in sub-block units cannot be performed efficiently, and the encoding / decoding processing can be speeded up. I could not. Specifically, in FIG. 2A, following the 16 × 16 pixel sub-block 10001, sub-blocks 10002 to 10009 of 8 × 8 pixels are processed in the order of numbers, and finally 16 × 16 pixels. Sub-block 10010 is processed. Since the quantization parameter of each sub-block is calculated as a difference using the quantization parameter of the previous sub-block as a predicted value, these need to be sequentially processed. For this reason, parallel processing in units of sub-blocks cannot be performed efficiently.

  Furthermore, when the quantization parameter is optimized in each sub-block, the acquisition of the difference value of the quantization parameter is performed according to the region quadtree structure, so that the difference value varies. For example, FIG. 2B shows a quantization parameter value at the center of each sub-block. In this figure, it is assumed that the quantization parameter value changes gently from the upper left to the lower right. Such a case is a phenomenon that easily occurs in a normal natural image. The quantization parameter of the sub-block 10001 is 12, and the difference is +2 in the sub-block 10002. In order, +4, −6, +6, −6, ± 0, +2, +4, and +2. In this way, when the area quadtree structure is followed, the value fluctuates and the generated code becomes large.

  Therefore, the present invention has been made to solve the above-described problem, and enables encoding / decoding of each sub-block in parallel, realizing high-speed processing and highly efficient quantization parameter code. The purpose is to realize the decoding and decoding.

In order to solve the above-described problems, the image coding apparatus of the present invention has the following configuration. That is, an image encoding apparatus for quantizing the image in units of blocks, a first quantization parameter blocks that are included in the image, is included in the image, after the first block the first difference value is a difference value between the quantization parameter of the second block to be coded, and the third quantization parameter of block that are included in the image, a plurality encompassed in the image obtaining means for obtaining a second difference value is a difference value between the average of the quantization parameters of at least two blocks are coded before the third block of the block, by the acquisition means Encoding means for encoding the acquired first difference value and the second difference value;
Have

  According to the present invention, it is possible to encode / decode quantization parameters with a low amount of code and highly efficient processing.

1 is a block diagram illustrating a configuration of an image encoding device according to a first embodiment. Diagram showing an example of block division Detailed block diagram of a quantization parameter encoding unit in the image encoding device according to the first embodiment 7 is a flowchart showing image encoding processing in the image encoding apparatus according to the first embodiment. Diagram showing parallel processing during encoding FIG. 6 is a block diagram illustrating a configuration of an image decoding device according to a second embodiment. Detailed block diagram of quantization parameter decoding unit according to embodiment 2 7 is a flowchart illustrating image decoding processing in the image decoding apparatus according to the second embodiment. Diagram showing parallel processing during decoding FIG. 9 is a block diagram illustrating a configuration of an image encoding device according to a third embodiment. Detailed block diagram of a quantization parameter encoding unit in the image encoding device according to the third embodiment 10 is a flowchart showing image encoding processing in the image encoding apparatus according to the third embodiment. FIG. 9 is a block diagram illustrating a configuration of an image decoding device according to a fourth embodiment. Detailed block diagram of a quantization parameter decoding unit in the image decoding apparatus according to the fourth embodiment 7 is a flowchart illustrating image decoding processing in the image decoding apparatus according to the second embodiment. Detailed block diagram of a quantization parameter encoding unit in the image encoding device according to the fifth embodiment 10 is a flowchart showing image encoding processing in the image encoding device according to the fifth embodiment. Detailed block diagram of the quantization parameter decoding unit in the image decoding apparatus according to the sixth embodiment 10 is a flowchart showing image decoding processing in the image decoding apparatus according to the sixth embodiment. The block diagram which shows the structural example of the hardware of the computer applicable to the image coding apparatus of this invention, and a decoding apparatus.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with reference to the accompanying drawings. The configurations shown in the following embodiments are merely examples, and the present invention is not limited to the illustrated configurations.

<Embodiment 1>
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an image encoding apparatus according to this embodiment. In FIG. 1, reference numeral 1000 denotes a terminal for inputting image data.

  Reference numeral 1001 denotes a block dividing unit that cuts out an input image in units of a plurality of basic blocks and divides the input image into sub blocks as necessary. Quantization control is performed in units of subblocks. For ease of explanation, the input image has an 8-bit pixel value, but the present invention is not limited to this. Further, the basic block size is 64 pixels × 64 pixels, and the sub-block minimum size is 8 pixels × 8 pixels. In this case, the basic block includes four sub-blocks. Further, the block division will be described by taking an example of a method of dividing the block into four halves, but the shape and size of the block are not limited thereto. The basic block only needs to include at least two sub-blocks. The division of the subblock is not particularly limited. For example, the whole may be divided into sub-blocks, and the amount of edges may be calculated and clustered for clustering. That is, a sub-block is set finely in a portion where many edges gather, and a large sub-block is set in a flat portion. Reference numeral 1002 denotes a quantization parameter determination unit that determines the quantization parameter of the basic block and the quantization parameter of each sub-block.

  Reference numeral 1003 denotes a block prediction unit that predicts each subblock divided by the block dividing unit 1001 in units of subblocks and calculates a prediction error of each subblock. It is assumed that intra prediction is performed in an intra frame in the case of a still image or a moving image, and motion compensation prediction is also performed in the case of a moving image. Reference numeral 1004 denotes a block transform unit that performs orthogonal transform on the prediction error of each sub-block and calculates orthogonal transform coefficients. Although it does not specifically limit regarding orthogonal transformation, you may use discrete cosine transformation, Hadamard transformation, etc. Reference numeral 1005 denotes a block quantization unit that quantizes the orthogonal transform coefficient using the quantization parameter in units of sub-blocks determined by the quantization parameter determination unit 1002. A quantization coefficient can be obtained by this quantization. Reference numeral 1006 denotes a block encoding unit that generates quantization coefficient code data by variable-length encoding the quantization coefficient in units of sub-blocks thus obtained. The encoding method is not particularly limited, but a Huffman code, an arithmetic code, or the like can be used. Reference numeral 1007 denotes a block reproduction image generation unit. The inverse operation of the block quantization unit and the block conversion unit 1004 is performed to reproduce the prediction error, and a decoded image of the basic block is generated from the result of the block prediction unit 1003. The reproduced image data is held and used for prediction by the block prediction unit 1003.

  Reference numeral 1008 denotes a quantization parameter encoding unit that encodes the quantization parameter of the basic block determined by the quantization parameter determination unit 1002 and the quantization parameter of each sub-block to generate quantization parameter code data.

  Reference numeral 1009 denotes an integrated encoding unit. Codes relating to header information and prediction are generated, and the quantization parameter code data generated by the quantization parameter encoding unit 1008 and the quantization coefficient code data generated by the block encoding unit 1006 are integrated. Reference numeral 1010 denotes a terminal, which is a terminal for outputting the bit stream generated by the integration encoding unit 1009 to the outside.

  An image encoding operation in the image encoding apparatus will be described below. In the present embodiment, moving image data is input in units of frames, but still image data for one frame may be input.

  The image data for one frame input from the terminal 1000 is input to the block dividing unit 1001 and is divided into basic blocks of 64 pixels × 64 pixels. Further, it is divided into sub-blocks of a minimum of 8 pixels × 8 pixels as necessary. Information on sub-block division and the divided image data are input to a quantization parameter determination unit 1002 and a block prediction unit 1003.

  The block prediction unit 1003 performs prediction with reference to the reproduction image held in the block reproduction image generation unit 1007, generates a prediction error, and inputs the prediction error to the block conversion unit 1004 and the block reproduction image generation unit 1007. The block transform unit 1004 performs orthogonal transform on the input prediction error, obtains an orthogonal transform coefficient, and inputs it to the block quantization unit 1005.

  On the other hand, the quantization parameter determination unit 1002 determines the optimum quantization parameter from the balance between the image quality and the code amount for each subblock in consideration of the input code amount generated for each subblock. For example, a technique as described in Japanese Patent Laid-Open No. 4-3231961 can be used. The determined quantization parameter of each sub-block is input to the block quantization unit 1005, the block reproduction image generation unit 1007, and the quantization parameter encoding unit 1008.

  The block quantization unit 1005 quantizes the orthogonal transform coefficient output from the block transform unit 1004 with the quantization parameter determined by the quantization parameter determination unit 1002 to generate a quantization coefficient. The generated quantized coefficients are input to the block encoding unit 1006 and the block reproduction image generating unit 1007. The block reproduction image generation unit 1007 reproduces the orthogonal transform coefficient with the quantization parameter determined by the quantization parameter determination unit 1002 from the input quantization coefficient. The orthogonal transform coefficient is subjected to inverse orthogonal transform to reproduce a prediction error. The reproduced prediction error is generated and retained as a reproduced image based on the pixel value or the like referred to at the time of prediction. On the other hand, the block encoding unit 1006 encodes the quantized coefficient, generates quantized coefficient code data, and outputs it to the integrated encoding unit 1009.

  The quantization parameter determined by the quantization parameter determination unit 1002 is encoded by the quantization parameter encoding unit 1008 in units of basic blocks.

  FIG. 3 shows a detailed block diagram of the quantization parameter encoding unit 1008. In FIG. 3, 1 is a terminal for inputting the quantization parameter of each sub-block from the quantization parameter determination unit 1002 of FIG. Reference numeral 2 denotes a quantization parameter holding unit that temporarily stores the input quantization parameter of each sub-block. Reference numeral 3 denotes a basic block quantization parameter determination unit that determines the quantization parameter of the basic block from the stored quantization parameter of each sub-block. Reference numeral 4 denotes a basic block quantization parameter encoding unit that generates basic block quantization parameter codes by encoding basic block quantization parameters. Reference numeral 5 denotes a terminal for outputting the generated basic block quantization parameter code to the integrated encoding unit 1009 in FIG. A sub-block quantization parameter difference unit 6 obtains a difference from the quantization parameter of each sub-block using the basic block quantization parameter. Reference numeral 7 denotes a sub-block quantization parameter encoding unit that encodes the difference to generate a sub-block quantization parameter difference value code. Reference numeral 8 denotes a terminal that outputs the sub-block quantization parameter code to the integrated encoding unit 1009 in FIG.

  In the above configuration, the quantization parameter holding unit 2 stores the sub-block quantization parameter input from the terminal 1 in units of basic blocks. Once stored, the basic block quantization parameter determination unit 3 calculates a basic block quantization parameter. In the present embodiment, the average value of the sub-block quantization parameters is calculated. In the case of FIG. 2B, the average value is 14.6. If the quantization parameter is encoded in integer units, rounding is performed and the basic block quantization parameter is set to 15. The determined basic block quantization parameter is input to the basic block quantization parameter encoding unit 4 and the sub-block quantization parameter difference unit 6. The basic block quantization parameter encoding unit 4 encodes the input basic block quantization parameter by Golomb encoding, generates a basic block quantization parameter code, and outputs it through the terminal 5.

  On the other hand, the sub-block quantization parameter difference unit 6 calculates the difference between each sub-block quantization parameter and the basic block quantization parameter. In the case of FIG. 2B, the difference values are -3, -1, +3, -3, +3, -3, -3, -1, -1, and +5 in the order of the area quadtree structure. These difference values are input to the sub-block quantization parameter encoding unit 7. The sub-block quantization parameter encoding unit 7 encodes these values together with whether or not there is a change. First, the quantization parameter of the first sub-block 10001 is different from 15 of the basic block quantization parameter. Therefore, a 1-bit value “1” and a difference value “−3” indicating that there is a change are encoded by Golomb encoding, and output from the terminal 8 as sub-block quantization parameter difference value encoded data. Subsequently, the difference value of the sub-block quantization parameter of the second sub-block 10002 is encoded. Since this difference value is different from the basic block quantization parameter, a code obtained by Golomb coding 1-bit values “1” and −1 indicating that there is a change is output from the terminal 8. Thereafter, similarly, a 1-bit value “1” indicating that there is a change and a sub block quantization parameter difference value are encoded to generate sub block quantization parameter difference value encoded data.

  Returning to FIG. 1, the integrated encoding unit 1009 generates codes such as an image sequence and a frame header, and obtains information such as a prediction mode from the block prediction unit 1003 and encodes each basic block. Subsequently, a basic block quantization parameter code is input from the quantization parameter encoding unit 1008. Thereafter, the sub-block quantization parameter difference value encoded data and each quantized coefficient code data are integrated for each sub-block and output from the terminal 1010 as a bit stream.

  FIG. 4 is a flowchart illustrating image encoding processing in the image encoding device according to the first embodiment. First, in step S001, the integrated encoding unit 1009 generates and outputs codes such as a sequence and a frame header.

  In step S002, the block division unit 1001 cuts out basic blocks from the upper left of the image in order from the input image.

  In step S003, block dividing section 1001 further divides the basic block into sub-blocks.

In step S004, the quantization parameter for each sub-block is determined. In step S005, the basic block quantization parameter is determined from the sub-block quantization parameter obtained in step S004. In this embodiment, for the sake of explanation, the average value of the quantization parameters of the sub-blocks in the basic block is calculated as the quantization parameter of the basic block.
In step S006, the basic block quantization parameter determined in step S005 is Golomb encoded and output as a basic block quantization parameter code.

  In step S007, subblock quantization parameters are encoded in units of subblocks. When the same quantization parameter as that of the basic block is used in the order of the area quadtree structure, a 1-bit code “0” is output as a code. If they are different, the difference between the sub-block quantization parameter and the basic block quantization parameter is encoded and output following the 1-bit code “1”.

  In step S008, prediction is performed on the image data of the sub-block, orthogonal transformation and quantization are performed on the prediction error, the obtained quantization coefficient is encoded, and quantization coefficient code data is output. .

In step S009, the obtained quantization coefficient is inversely quantized and inversely transformed to calculate a prediction error. A reproduced image of the sub-block is generated from the prediction error and a predicted value from the reproduced image.
In step S010, the image coding apparatus determines whether or not the coding of all the sub-blocks in the basic block has been finished. If finished, the process proceeds to step S011, and if not finished, the next step is step S011. The process returns to step S007 for the sub-block.

  In step S011, the image encoding apparatus determines whether or not encoding of all the basic blocks has been completed, and if completed, stops all operations and ends the process. The process returns to step S002 for the next basic block.

  With the above configuration and operation, it is possible to suppress the amount of code generated by encoding the difference value of each sub-block quantization parameter using the basic block quantization parameter, particularly by the processing from step S005 to step S009. .

  In this embodiment, the average value is used as it is. However, the present invention is not limited to this, and an existing sub-block quantization parameter closest to the average value may be selected. For example, in the example of FIG. 2B, the average value is 14.6 as described above, but the nearest actual sub-block quantization parameter value 14 may be used instead of rounding off. In this way, the code representing the change can be set to “0”, and the transmitted sub-block quantization parameter difference value can be reduced.

  Furthermore, in this configuration, prediction, quantization, transformation, and encoding can be efficiently performed in parallel, and there is an effect that speeding up can be achieved.

  FIG. 5 shows an example in which the sub-blocks of the basic block shown in FIG. Here, for the sake of explanation, it is assumed that three processors are used for the encoding process. With these processors (A to C), calculation of quantization parameter (QP) of each sub-block, calculation / coding of quantization parameter difference value (ΔQP), orthogonal transformation / quantization of prediction error, coding of quantization coefficient Take as an example the case of performing the conversion. At this time, these codes are integrated by another processor.

  FIG. 5A shows an example of conventional parallel processing. First, the processing of sub-block 10001 is assigned to processor A, the processing of sub-block 10002 is assigned to processor B, and the processing of sub-block 10003 is assigned to processor C. Regarding the calculation of QP, the processing time varies depending on the size of the block, the complexity of the image, and the like. The quantization parameter calculation of the sub-block 10001 having a large block size tends to take longer than the sub-block 10002 and the sub-block 10003.

  Subsequent to the quantization parameter calculation, a quantization parameter difference value calculation is performed. The sub block quantization parameter difference value of the sub block 10002 cannot be calculated unless the sub block quantization parameter calculation of the sub block 10001 is completed. Accordingly, during this time, the processor B is in a standby state until the processor A calculates the sub-block quantization parameter of the sub-block 10001. Further, when the quantization parameter calculation of the sub-block 10002 takes longer than the sub-block 10003, the calculation of the difference value of the sub-block 10003 is not required unless the calculation of the sub-block quantization parameter of the sub-block 10002 is completed. During this time, the processor C is in a standby state until the processor B calculates the sub-block quantization parameter of the sub-block 10002.

  In contrast, FIG. 5B is a diagram showing an example of parallel processing in the present embodiment. As in the conventional case, the processing of sub-block 10001 is assigned to processor A, the processing of sub-block 10002 is assigned to processor B, and the processing of sub-block 10003 is assigned to processor C. Subsequent to the calculation of the sub-block quantization parameter, the sub-block quantization parameter difference value is calculated. The calculation of the sub-block quantization parameter difference value of the sub-block 10002 can be started immediately after the calculation of the sub-block quantization parameter since the basic block quantization parameter has been calculated. As described above, parallelization can be efficiently performed according to the present invention. In particular, when sub-blocks of a plurality of sizes are mixed, the effect of reducing the processing interval is increased.

  In this embodiment, the value of the basic block quantization parameter itself is encoded. However, prediction may be performed using the previously processed basic block quantization parameter.

  Furthermore, in this embodiment, for the purpose of explanation, the basic block is 64 pixels × 64 pixels and the sub-block is 8 pixels × 8 pixels. However, the present invention is not limited to this. For example, the basic block can be changed to a block size such as 128 pixels × 128 pixels, and the shape of the basic block and sub-block is not limited to a square, and the essence of the invention is a rectangle such as 8 pixels × 4 pixels. does not change.

  In this embodiment, the basic block quantization parameter is the average value of each sub-block quantization parameter, but the present invention is not limited to this. For example, it may be the median value of the sub-blocks, or of course the value of the most frequently used sub-block quantization parameter. Of course, it is possible to prepare a plurality of calculation methods and select the most efficient basic block quantization parameter.

  In addition, although 1 bit of the code | symbol which shows the presence or absence of a change was provided as subblock quantization parameter difference value encoding data, it is not limited to this, Even if there is no change, a subblock quantization parameter difference value Of course, it may be encoded.

  In the present embodiment, the basic block quantization parameter, the sub-block quantization parameter difference value, and the quantization coefficient are encoded using Golomb coding. However, the present invention is not limited to this. For example, Huffman coding or other arithmetic coding may be used, and the value may be output as it is without being coded.

  In the present embodiment, a frame using intra prediction has been described as an example. However, it is obvious that a frame that can use inter prediction that performs motion compensation for prediction can also be used.

<Embodiment 2>
In this embodiment, an image decoding method for decoding code data encoded using the encoding method of the first embodiment will be described. FIG. 6 is a block diagram showing a configuration of an image decoding apparatus according to Embodiment 2 of the present invention.

  Reference numeral 1100 denotes a terminal for inputting an encoded bit stream. A decoding / separating unit 1101 decodes the header information of the bit stream and separates a necessary code from the bit stream and outputs the code to the subsequent stage. The decoding / separating unit 1101 performs the reverse operation of the unified encoding unit 1009 of FIG. Reference numeral 1102 denotes a quantization parameter decoding unit that decodes the encoded data of the quantization parameter. Reference numeral 1103 denotes a block decoding unit that decodes the quantization coefficient code of each sub-block and reproduces the quantization coefficient. Reference numeral 1104 denotes a block inverse quantization unit that performs inverse quantization on the quantization coefficient using the sub-block quantization parameter reproduced by the quantization parameter decoding unit 1102 and reproduces an orthogonal transform coefficient. Reference numeral 1105 denotes a block inverse transform unit that performs inverse orthogonal transform of the block transform unit 1004 in FIG. 1 and reproduces a prediction error. A block reproduction unit 1106 reproduces sub-block image data from the prediction error and decoded image data. Reference numeral 1107 denotes a block synthesizing unit that arranges reproduced sub-block image data at respective positions and reproduces basic block image data.

  An image decoding operation in the image decoding apparatus will be described below. In the present embodiment, the moving image bitstream generated in the first embodiment is input in units of frames. However, a configuration may be adopted in which a still image bitstream for one frame is input.

  In FIG. 6, stream data for one frame input from a terminal 1100 is input to a decoding / separating unit 1101, and header information necessary for reproducing an image is decoded. Subsequent basic block quantization parameter codes are input to the quantization parameter decoding unit 1102. Further, the subsequent sub-block quantization parameter difference value code is also input to the quantization parameter decoding unit 1102.

  FIG. 7 is a block diagram showing details of the quantization parameter decoding unit 1102. Reference numeral 101 denotes a terminal for inputting a basic block quantization parameter code from the decoding / separating unit 1101 in FIG. Reference numeral 102 denotes a terminal for inputting sub-block quantization parameter difference encoded data from the decoding / separating unit 1101 in FIG. Reference numeral 103 denotes a basic block quantization parameter decoding unit that receives and decodes a basic block quantization parameter code and reproduces the basic block quantization parameter. A sub-block quantization parameter decoding unit 104 decodes the sub-block quantization parameter difference value encoded data and reproduces each sub-block quantization parameter difference value. Reference numeral 105 denotes a sub-block quantization parameter adding unit that adds the reproduced basic block quantization parameter and each sub-block quantization parameter difference value to reproduce each sub-block quantization parameter. Reference numeral 106 denotes a terminal for outputting each reproduced sub-block quantization parameter to the block inverse quantization unit 1104 in FIG.

  The basic block quantization parameter code input from the terminal 101 is input to the basic block quantization parameter decoding unit 103, and the basic block quantization parameter is reproduced by decoding the Golomb code and held.

  The sub-block quantization parameter difference value encoded data input from the terminal 102 is input to the sub-block quantization parameter decoding unit 104, and the sub-block quantization parameter difference value is reproduced by decoding Golomb code. That is, 1 bit representing whether or not there is a change in the basic block quantization parameter is decoded, and if there is no change, 0 is output as the sub-block quantization parameter difference value. If there is a change, the sub-block quantization parameter difference value is subsequently decoded and output. The sub-block quantization parameter difference value is added to the basic block quantization parameter reproduced by the sub-block quantization parameter adding unit 105 to reproduce the sub-block quantization parameter and output from the terminal 106.

  Returning to FIG. 6, the quantized coefficient code data of the sub-block separated by the decoding / separating unit 1101 is input to the block decoding unit 1103, and each quantized coefficient is reproduced by decoding the Golomb code. When the quantization coefficient of the sub-block is reproduced, it is input to the block inverse quantization unit 1104. The block inverse quantization unit 1104 performs inverse quantization from the input subblock quantization coefficients and subblock quantization parameters to reproduce orthogonal transform coefficients. The reconstructed orthogonal transform coefficient is inverse transformed by the block inverse transform unit 1105 to reproduce the prediction error. The reproduced prediction error is input to the block reproduction unit 1106, and prediction is performed from the decoded surrounding pixel data or the pixel data of the previous frame, and the image data of the sub-block is reproduced. The block synthesizing unit 1107 arranges the reproduced sub-block image data at the respective positions, and reproduces the basic block image data. The reproduced basic block image data is output to the outside via a terminal 1108. Further, it is input to the block reproduction unit 1106 and used for prediction value calculation.

  FIG. 8 is a flowchart illustrating an image decoding process in the image decoding apparatus according to the second embodiment. First, in step S101, the decoding / separating unit 1101 decodes the header information.

  In step S102, the basic block quantization parameter decoding unit 103 decodes the basic block quantization parameter code and reproduces the basic block quantization parameter.

  In step S103, the subblock quantization parameter decoding unit 104 decodes the subblock quantization parameter difference value encoded data, and reproduces the subblock quantization parameter difference value. Further, the basic block quantization parameter is added to reproduce the sub-block quantization parameter.

  In step S104, the quantization coefficient code data of the sub-block is decoded, the quantization coefficient is reproduced, inverse quantization and inverse orthogonal transformation are performed, and the prediction error is reproduced. Further, prediction is performed from the decoded surrounding pixel data or the pixel data of the previous frame, and the decoded image of the sub-block is reproduced.

  In step S105, the decoded image of the sub-block is arranged in the decoded image of the basic block. In step S106, the image decoding apparatus determines whether or not decoding of all the subblocks in the basic block has been completed. If completed, the process proceeds to step S107. Return to step S103 for the block.

  In step S107, the decoded image of the basic block is arranged in the decoded image of the frame. In step S108, the image decoding apparatus determines whether or not the decoding of all the basic blocks has been completed. If the decoding has been completed, the image decoding apparatus stops all the operations and ends the process. The process returns to step S102 for the basic block.

  With the above configuration and operation, it is possible to decode the bitstream generated in the first embodiment and reduce the code amount, and obtain a reproduced image.

  Furthermore, if the code can be identified by a delimiter for each sub-block, sub-block quantization parameter reproduction, sub-block de-quantization, inverse transform, and image data reproduction can be efficiently performed in parallel. It is possible to perform high-speed decoding.

  FIG. 9 shows an example in which a prediction error is reproduced by decoding / inverse quantization / inverse transform of the sub-blocks of the basic block shown in FIG. As in FIG. 5 of the first embodiment, it is assumed here that three processors are used for explanation. An example of the case where these processors perform quantization parameter difference value (ΔQP) decoding, quantization parameter (QP) reproduction, quantization coefficient decoding, and quantization coefficient inverse quantization / inverse orthogonal transformation. Take it. At this time, these codes are separated by another processor.

  FIG. 9A shows an example of conventional parallel processing. First, the processing of sub-block 10001 is assigned to processor A, the processing of sub-block 10002 is assigned to processor B, and the processing of sub-block 10003 is assigned to processor C. Since the processor A is the head, the sub-block quantization parameter itself is decoded, and the processors B and C decode each sub-block quantization parameter difference value, and subsequently reproduce the sub-block quantization parameter. This is realized by adding the sub-block quantization parameter and the sub-block quantization parameter difference value of the previous sub-block that becomes the predicted value of the sub-block quantization parameter.

  Reproduction of the sub-block quantization parameter of the sub-block 10002 is not required unless decoding of the quantization parameter of the sub-block 10001 is completed. Accordingly, during this time, the processor B is in a standby state until the quantization parameter of the sub-block 10001 is reproduced by the processor A.

  The same applies to the reproduction of the quantization parameter of the sub-block 10002, and the processor C is in a standby state until the reproduction of the quantization parameter of the sub-block 10002 by the processor B. Thereafter, the processing is completed for the processor in the order of the area quadtree structure, that is, in the order of sub-block 10004, sub-block 10005, and sub-block 10006. The reproduction of the sub-block quantization parameter of the sub-block 10006 is not required unless the reproduction of the quantization parameter of the sub-block 10005 is completed. Therefore, during this time, the processor C is in a standby state until the quantization parameter of the sub-block 10005 is reproduced by the processor A.

  On the other hand, FIG. 9B is a diagram showing an example of parallel processing in the present embodiment. First, the processor A decodes and holds the basic block quantization parameter. Hereinafter, as in the conventional case, the processing of sub-block 10001 is assigned to processor A, the processing of sub-block 10002 is assigned to processor B, and the processing of sub-block 10003 is assigned to processor C. Subsequent to the decoding of the sub-block quantization parameter difference value, the sub-block quantization parameter is reproduced. The reproduction of the quantization parameter of the sub-block 10002 can be started immediately after the decoding of the sub-block quantization parameter difference value since the basic block quantization parameter has been reproduced. According to the present invention, parallelization can be performed efficiently. In particular, when sub-blocks of a plurality of sizes are mixed, the effect of reducing the processing interval is increased.

  Further, when considering an application such as editing that cuts out a part of image data, for example, consider a case of cutting out only the sub-block 10008 in FIG. In the case of the conventional example, decoding of sub-blocks 10001 to 1007 is necessary. According to the present invention, it is understood that if only the sub-block 10001 and the sub-block 10006 are decoded, decoding can be performed even if intra prediction is included. By skipping the decoding process in this way, the processing speed can be improved.

  Further, as in the first embodiment, the block size, the processing unit size, the arrangement of reference processing units and their pixels, and the codes are not limited thereto.

  In the present embodiment, the basic block quantization parameter, the sub-block quantization parameter difference value, and the quantization coefficient have been described using Golomb coding, but the present invention is not limited to this. For example, Huffman coding or other arithmetic coding may be used, and the value may be output as it is without being coded.

  In the present embodiment, a frame using intra prediction has been described as an example. However, it is obvious that a frame that can use inter prediction that performs motion compensation for prediction can also be used.

<Embodiment 3>
FIG. 10 is a block diagram showing an image encoding apparatus according to this embodiment. In this embodiment, the quantization parameter of the first sub-block is set as a basic block quantization parameter, and the basic block quantization parameter is not individually encoded. Further, the difference from the first embodiment is that there is no code indicating whether or not there is a change. However, similarly to the first embodiment, encoding using a code indicating the presence or absence of a change may be performed. 10, parts having the same functions as those in FIG. 1 of the first embodiment are given the same numbers, and descriptions thereof are omitted.

  Reference numeral 1208 denotes a quantization parameter encoding unit that encodes sub-block quantization parameters and generates quantization parameter code data. Reference numeral 1209 denotes an integrated encoding unit. Codes relating to header information and prediction are generated, and the quantization parameter code data generated by the quantization parameter encoding unit 1208 and the quantization coefficient code data generated by the block encoding unit 1006 are integrated.

  FIG. 11 shows a detailed block diagram of the quantization parameter encoding unit 1208. In FIG. 11, the same numbers are assigned to portions that perform the same functions as those in FIG. 3 of the first embodiment, and description thereof is omitted.

  Reference numeral 200 denotes a selector that selects an output destination according to the position of the sub-block of the input sub-block quantization parameter. Reference numeral 203 denotes a basic block quantization parameter holding unit that holds the quantization parameter of the first sub-block as a basic block quantization parameter in the order of the area quadtree structure of the basic block. Reference numeral 206 denotes a sub-block quantization parameter difference unit that calculates a difference value between the quantization parameter of each subsequent sub-block and the basic block quantization parameter. A sub-block quantization parameter encoding unit 207 encodes the quantization parameter of the first sub-block and the sub-block quantization parameter difference value of each sub-block.

  In the above configuration, as in the first embodiment, the sub-block quantization parameters are input from the terminal 1 in the order of the area quadtree structure. The selector 200 outputs the quantization parameter of the first subblock in the order of the area quadtree structure to the basic block quantization parameter holding unit 203. Sub-block quantization parameters thereafter are output to the sub-block quantization parameter difference unit 206.

  The sub-block of the first sub-block is held in the basic block quantization parameter holding unit 203 as a basic block quantization parameter. Thereafter, the leading quantization parameter is also input to the sub-block quantization parameter difference unit 206. Since the subblock quantization parameter is the head of the basic block, the difference is not calculated and is output to the subsequent subblock quantization parameter encoding unit 207 as it is. Subblock quantization parameter encoding section 207 encodes the input subblock quantization parameter using Golomb code, and outputs it from terminal 8 as subblock quantization parameter encoded data.

  Subsequently, the sub-block quantization parameters are input from the terminal 1 in the order of the area quadtree structure, and are input to the sub-block quantization parameter difference unit 206 via the selector 200. The sub-block quantization parameter difference unit 206 calculates a difference value between the input sub-block quantization parameter and the basic block quantization parameter held in the basic block quantization parameter holding unit 203. The sub-block quantization parameter encoding unit 207 encodes the quantization parameter difference value using Golomb code, generates sub-block quantization parameter difference value encoded data, and outputs it from the terminal 8 as sub-block quantization parameter encoded data. . Thereafter, the difference is obtained and encoded with respect to the sub-block quantization parameters of the sub-blocks in the basic block.

  FIG. 12 is a flowchart illustrating image encoding processing in the image encoding device according to the third embodiment. In FIG. 12, the same numbers are assigned to portions that perform the same functions as those in FIG. 4 of the first embodiment, and description thereof is omitted.

  From step S001 to step S004, subblock division and subblock quantization parameters are determined as in the first embodiment.

  In step S205, the head sub-block quantization parameter is held as a basic block quantization parameter.

In step S206, it is determined whether or not the input sub block is the first sub block of the basic block. If it is the first sub block, the process proceeds to step S208. Otherwise, the process proceeds to step S207. In step S207, the difference between the basic block quantization parameter held in step S205 and the input sub-block quantization parameter is calculated.
In step S208, the input sub-block quantization parameter or sub-block quantization parameter difference value is encoded by Golomb code and output as sub-block quantization parameter encoded data.

  Steps S008 and S009 operate in the same manner as in the first embodiment. In step S210, it is determined whether or not processing has been completed for all sub-blocks in the basic block. If not completed, the process proceeds to step S206 for processing of the next sub-block. If completed, the process proceeds to step S011. Thereafter, the entire image is encoded as in the first embodiment. With the configuration and operation described above, the basic block quantization parameter is used as the first sub-block quantization parameter, so that it is not necessary to send the basic block quantization parameter, so that the coding efficiency is improved.

  Further, it is possible to effectively perform parallel processing as in the first embodiment. That is, in FIG. 5A, the processors B and C need to wait for calculation of the first sub-block quantization parameter of the processor A for the first time. However, thereafter, the quantization parameter difference value of the sub-block 10005 can be calculated without waiting for the processing of the sub-block 10004.

  A method for encoding the basic block quantization parameter according to the first embodiment and a code for switching the basic block quantization parameter according to the present embodiment to be the first sub-block quantization parameter are provided. Of course you can choose.

  In addition, although it demonstrated that the same encoding was performed about the head subblock quantization parameter (basic block quantization parameter) and the subsequent subblock quantization parameter difference value, it is not limited to this. Of course, it does not matter if individual encoding methods are applied.

  In the present embodiment, the basic block quantization parameter, the sub-block quantization parameter difference value, and the quantization coefficient are encoded using Golomb coding. However, the present invention is not limited to this. For example, Huffman coding or other arithmetic coding may be used.

  In the present embodiment, a frame using intra prediction has been described as an example. However, it is obvious that a frame that can use inter prediction that performs motion compensation for prediction can also be used.

<Embodiment 4>
In the present embodiment, an image decoding method for decoding code data encoded using the encoding method of the third embodiment will be described. FIG. 13 is a block diagram illustrating an image decoding apparatus that decodes code data encoded using the encoding method according to the third embodiment. In FIG. 13, the same numbers are assigned to portions that perform the same functions as those in FIG. 6 of the second embodiment, and description thereof is omitted.

  In FIG. 13, a decoding / separating unit 1301 decodes header information of a bit stream, separates necessary codes from the bit stream, and outputs them to the subsequent stage. Reference numeral 1302 denotes a quantization parameter decoding unit that reproduces sub-block quantization parameters. The decoding / separation unit 301 and the quantization parameter decoding unit 302 in FIG.

An image decoding operation in the image decoding apparatus will be described below. In the present embodiment, the moving image bitstream generated in the third embodiment is input in units of frames. However, a configuration may be adopted in which a still image bitstream for one frame is input.
As in the second embodiment, the stream data for one frame input from the terminal 1100 is input to the decoding / separating unit 1301, and the header information necessary for reproducing the image is decoded. The subsequent sub-block quantization parameter encoded data is input to the quantization parameter decoding unit 1302 in the order of the area quadtree structure.

  FIG. 14 is a detailed block diagram of the quantization parameter decoding unit 1302. In FIG. 14, the same numbers are assigned to portions that perform the same functions as those in FIG. 7 of the second embodiment, and description thereof is omitted.

  A sub-block quantization parameter decoding unit 304 decodes the sub-block quantization parameter and the sub-block quantization parameter difference value encoded data, and reproduces each sub-block quantization parameter difference value. Reference numeral 300 denotes a selector that selects an output destination according to the position of the sub-block of the input sub-block quantization parameter. Reference numeral 310 denotes a basic quantization parameter holding unit that holds the first decoded sub-block quantization parameter as a basic block quantization parameter. Reference numeral 305 denotes a sub-block quantization parameter addition unit that adds the held basic block quantization parameter and each sub-block quantization parameter difference value to reproduce each sub-block quantization parameter.

  In the above configuration, at the start of decoding of the basic block, the selector 300 sets the output destination as the basic block quantization parameter holding unit 310. The sub-block quantization parameter encoded data of the first sub-block of the basic block input from the terminal 102 is input to the sub-block quantization parameter decoding unit 104, and the sub-block quantization parameter is reproduced by decoding Golomb code. The sub-block quantization parameter of the first sub-block is input to the basic block quantization parameter holding unit 310 via the selector 300 and is held during the processing of the basic block. Further, the sub-block quantization parameter of the first sub-block is also input to the sub-block quantization parameter adding unit 305. The sub-block quantization parameter adding unit 305 outputs the reproduced sub-block quantization parameter from the terminal 106 because it is not a difference value for the first sub-block. When the first sub-block quantization parameter is recorded in the basic block quantization parameter holding unit 310, the selector 300 sets the output destination to the sub-block quantization parameter adding unit 305.

  Subsequently, the second and subsequent sub-block quantization parameter difference value encoded data is input to the sub-block quantization parameter decoding unit 304. The input sub-block quantization parameter difference value encoded data reproduces the sub-block quantization parameter difference value by decoding Golomb code. The sub-block quantization parameter adding unit 305 adds the sub-block quantization parameter difference value input via the selector 300 to the held basic block quantization parameter. In this way, the sub-block quantization parameter is reproduced and output from the terminal 106. Thereafter, decoding is performed on the sub-block quantization parameter of the sub-block in the basic block, a sub-block quantization parameter difference value is obtained and added to reproduce the sub-block quantization parameter.

  FIG. 15 is a flowchart showing image decoding processing in the present embodiment. In FIG. 15, the same numbers are assigned to portions that perform the same functions as those in FIG. 8 of the second embodiment, and description thereof is omitted.

  In step S101, header information is decoded as in the second embodiment. In step S310, it is determined whether the sub-block to be decoded is the first sub-block of the basic block. If the sub-block is the first sub-block, the process proceeds to step S311. Otherwise, the process proceeds to step S303.

  In step S311, the input code related to the sub-block quantization parameter is encoded data of the sub-block quantization parameter. This is decoded with Golomb code. The decoding result is held as a basic block quantization parameter. Thereafter, the process proceeds to step S104 to generate a decoded image of the first sub-block.

  In step S303, the code related to the input sub-block quantization parameter is encoded data of the sub-block quantization parameter difference value. This is decoded with Golomb code to reproduce the sub-block quantization parameter difference value. The reproduced sub-block quantization parameter difference value is added to the basic block quantization parameter held in step S311. The added result becomes a sub-block quantization parameter. Proceed to step S104 to generate decoded images of the second and subsequent sub-blocks.

  Thereafter, similarly to the second embodiment, generation of a decoded image of a sub-block and reproduction of a frame image are performed.

  With the above configuration and operation, it is possible to decode the encoded data generated in the third embodiment and suppressing the code amount without individually encoding the basic quantization parameter.

  Further, it is possible to effectively perform parallel processing as in the second embodiment. That is, in FIG. 9B, instead of decoding the quantization parameter of the processor A, the decoding of the first sub-block quantization parameter of the basic block is performed by the decoding of the basic block quantization parameter and the first sub-block quantization parameter difference value. It will replace decryption. As a result, B and C need to wait for the decoding of the first sub-block quantization parameter of processor A for the first time, but thereafter, the reproduction of the quantization parameter of all sub-blocks does not wait for the processing of other sub-blocks. Will be able to do.

  In the present embodiment, the basic block quantization parameter, the sub-block quantization parameter difference value, and the quantization coefficient have been described using Golomb coding, but the present invention is not limited to this. For example, Huffman coding or other arithmetic coding may be used.

  In addition, when a code for switching the basic block quantization parameter in the third embodiment and switching the basic block quantization parameter of the present embodiment to be the first subblock quantization parameter is provided, the code is interpreted. Step S102 of FIG. 8 is executed. Alternatively, it may be selected whether to execute steps S310, S311, and S303 in FIG.

  In the present embodiment, a frame using intra prediction has been described as an example. However, it is obvious that a frame that can use inter prediction that performs motion compensation for prediction can also be used.

<Embodiment 5>
In the present embodiment, an embodiment will be described in which the basic block quantization parameter is determined using the sub-block quantization parameter of the immediately preceding basic block.

  In this embodiment, the encoding apparatus has the same configuration as that of FIG. However, the configuration of the quantization parameter encoding unit 1208 is different.

  FIG. 16 is a block diagram showing a detailed configuration of the quantization parameter encoding unit 1208 of this embodiment.

  In FIG. 16, reference numeral 400 denotes a selector, which selects an input destination according to the position of the basic block of the input sub-block quantization parameter. A sub-block quantization parameter holding unit 410 holds the sub-block quantization parameter of the previous basic block. Reference numeral 403 denotes a basic block quantization parameter determination unit. The basic block quantization parameter of the basic block to be encoded is determined from the sub-block quantization parameter held by the sub-block quantization parameter holding unit 410. A sub-block quantization parameter difference unit 406 calculates a difference value between the basic block quantization parameter and each sub-block quantization parameter. Reference numeral 407 denotes a sub-block quantization parameter encoding unit that encodes the quantization parameter of the first sub-block and the sub-block quantization parameter difference value of each sub-block.

  In the above configuration, as in the third embodiment, image data is input from the terminal 1000, and is divided into sub-blocks by the block dividing unit 1001, and the quantization parameter of each sub-block is determined by the quantization parameter determining unit 1002. The determined sub-block quantization parameter is input to the quantization parameter encoding unit 1208.

  Turning to FIG. 16, if the input sub-block quantization parameter is the first sub-block of the first basic block of the image, the selector 400 selects the input from the terminal 1. The input sub-block quantization parameter is input to the basic block quantization parameter determination unit 403 via the sub-block quantization parameter holding unit 410, the sub-block quantization parameter difference unit 406, and the selector 400. The sub-block quantization parameter holding unit 410 holds a sub-block quantization parameter for processing of the next basic block. The basic block quantization parameter determination unit 403 holds the input sub-block quantization parameter as the basic block quantization parameter, similarly to the basic block quantization parameter holding unit 203 of the third embodiment. The subblock quantization parameter difference unit 406 outputs the subblock quantization parameter as it is, like the subblock quantization parameter difference unit 206 of the third embodiment. The sub-block quantization parameter encoding unit 407 encodes the head sub-block quantization parameter with Golomb code and outputs it from the terminal 8.

  Thereafter, the other sub-block quantization parameters of the first basic block of the image are input from the terminal 1 and input to the sub-block quantization parameter holding unit 410 and the sub-block quantization parameter difference unit 406. The sub-block quantization parameter difference unit 406 calculates a difference value between the basic block quantization parameter output from the basic block quantization parameter determination unit 403 and the input. The difference value is input to the sub-block quantization parameter encoding unit 407, encoded in the same manner as in the third embodiment, and output from the terminal 8.

  On the other hand, the processing for a basic block that is not the head of an image to be subsequently input will be described. Prior to the basic block encoding process, the selector 400 selects the sub-block quantization parameter holding unit 410 as an input destination. The basic block quantization parameter determination unit 403 calculates an average value of the held sub-block quantization parameters and sets this as a basic block quantization parameter. Thereafter, the sub-block quantization parameter of the basic block is input from the terminal 1 to the sub-block quantization parameter difference unit 406. The sub-block quantization parameter difference unit 406 calculates a difference value between the basic block quantization parameter output from the basic block quantization parameter determination unit 403 and the input. The difference value is input to the sub-block quantization parameter encoding unit 407, encoded in the same manner as in the third embodiment, and output from the terminal 8.

  FIG. 17 is a flowchart illustrating image encoding processing in the image encoding device according to the fifth embodiment. In FIG. 17, the same numbers are assigned to portions that perform the same functions as those in FIG. 4 of the first embodiment, and description thereof is omitted.

  In steps S001 to S003, encoding of header information, division of basic blocks, and division of sub-blocks are performed as in the first embodiment. In step S401, it is determined whether or not the basic block is the head of the image. If it is the head, the process proceeds to step S402; otherwise, the process proceeds to step S409. In step S402, it is determined whether or not the head sub block is the head sub block. If it is the first sub-block, the process proceeds to step S403, and if not, the process proceeds to step S406.

  In step S403, the sub-block quantization parameter of the first sub-block of the first basic block is determined and stored so that it can be referred to when processing the next basic block. In step S404, the sub-block quantization parameter determined in step S403 is held as a basic block quantization parameter. In step S405, the sub-block quantization parameter determined in step S403 is encoded, and the process proceeds to step S008. In step S406, the sub-block quantization parameter of the sub-block is determined and stored so that it can be referred to when processing the next basic block.

  In step S407, the basic block quantization parameter held in step S404 is subtracted from the sub-block quantization parameter determined in step S406. Thereby, a sub-block quantization parameter difference value of the sub-block is calculated. In step S408, the quantization parameter difference value calculated in step S407 is encoded to generate quantization parameter difference value encoded data, and the process proceeds to step S008. In step S409, it is determined whether the basic block is not the first sub-block of the basic block. If it is the first sub-block, the process proceeds to step S410, and if not, the process proceeds to step S406. In step S410, the basic block quantization parameter of the basic block is calculated with reference to the sub-block quantization parameter of the previous basic block held in steps S403 to S406. In the present embodiment, an average value of the sub-block quantization parameters is calculated and used as a basic block quantization parameter. In step S411, the sub-block quantization parameter of the sub-block is determined and held so that it can be referred to when processing the next basic block.

  In step S412, the basic block quantization parameter calculated in step S410 is subtracted from the sub-block quantization parameter determined in step S411. Thereby, a sub-block quantization parameter difference value of the sub-block is calculated.

  In step S413, the quantization parameter difference value calculated in step S412 is encoded to generate quantization parameter difference value encoded data, and the process proceeds to step S008. In step S414, the image coding apparatus determines whether or not the coding of all the sub-blocks in the basic block has been finished. If finished, the process proceeds to step S011; The process returns to step S401 for the sub-block. Steps S008, S009, and S011 operate in the same manner as in the first embodiment, and encode the entire image.

  With the above configuration and operation, the basic block quantization parameter is determined using the sub-block quantization parameter of the previous basic block, so that the basic block quantization parameter can be determined simultaneously with the start of the processing of the basic block. This has the effect of minimizing processing delay. Also, since the basic block quantization parameter is generated from the sub-block quantization parameter of the previous basic block, it is not necessary to send the basic block quantization parameter, so that the coding efficiency is improved.

  Further, it is possible to effectively perform parallel processing as in the first embodiment. That is, in FIG. 5B, the basic block quantization parameter is calculated by the sub-block quantization parameter of the previous basic block before encoding. As a result, the quantization parameter difference values of all the sub blocks can be calculated without waiting for the processing of each sub block.

  In the present embodiment, the sub-block quantization parameter of the first sub-block is encoded as it is only in the case of the first basic block of the image. However, the present invention is not limited to this. That is, a configuration like a slice composed of a plurality of basic blocks may be used, and the same processing may be performed on the top basic block.

  In the present embodiment, the determination is made with reference to the sub-block quantization parameter of the previous basic block, but the present invention is not limited to this. It is also possible to use it as a parameter. Furthermore, it is of course possible to refer to subblock quantization parameters or basic block quantization parameters of surrounding basic blocks.

  In this embodiment, the basic block quantization parameter is the average value of the sub-block quantization parameters of the previous basic block. However, the present invention is not limited to this. For example, it may be the median value of the sub-blocks, or of course the value of the most frequently used sub-block quantization parameter. Of course, a plurality of calculation methods may be prepared, and the most efficient basic block quantization parameter may be selected and encoded using a code representing the method.

  In the present embodiment, a frame using intra prediction has been described as an example. However, it is obvious that a frame that can use inter prediction that performs motion compensation for prediction can also be used.

<Embodiment 6>
In the present embodiment, an image decoding method for decoding code data encoded using the encoding method of the fifth embodiment will be described. In this embodiment, the encoding apparatus has the same configuration as that of FIG. However, the configuration of the quantization parameter decoding unit 1302 is different.

  FIG. 18 is a block diagram showing a configuration of a quantization parameter decoding unit 1302 according to Embodiment 6 of the present invention. In FIG. 18, the same numbers are assigned to portions that perform the same functions as those in FIG. 14 of the fourth embodiment, and the description thereof is omitted.

  Reference numeral 500 denotes a selector, which selects an output destination according to the position of the input sub-block quantization parameter sub-block and the basic block of the sub-block. Reference numeral 501 denotes a sub-block quantization parameter decoding unit that decodes a code when the sub-block quantization parameter itself is encoded and reproduces the sub-block quantization parameter. Reference numeral 502 denotes a sub-block quantization parameter difference value decoding unit that decodes the code when the sub-block quantization parameter difference value is encoded, and reproduces the sub-block quantization parameter difference value. A selector 503 selects an input destination according to the position of the input sub-block quantization parameter sub-block and the basic block of the sub-block. Reference numeral 504 denotes a basic block quantization parameter determination unit that determines basic block quantization parameters. Reference numeral 505 denotes a sub-block quantization parameter addition unit that adds the determined basic block quantization parameter and each sub-block quantization parameter difference value to reproduce each sub-block quantization parameter. A selector 506 selects an input destination according to the position of the input sub-block quantization parameter sub-block and the basic block of the sub-block. Reference numeral 507 denotes a sub-block quantization parameter holding unit that holds the reproduced sub-block quantization parameters.

  An image decoding operation in the image decoding apparatus will be described below. In this embodiment, a moving image bit stream is input in units of frames. However, a configuration may be adopted in which a still image bit stream for one frame is input.

  Prior to the decoding process of the bit stream for one frame, the selector 500 sets the output destination as the sub-block quantization parameter decoding unit 501, and the selector 503 sets the input destination as the sub-block quantization parameter decoding unit 501. The selector 505 sets the input destination as the sub-block quantization parameter decoding unit 501.

  First, the encoded data of the sub-block quantization parameter of the head basic block is input to the sub-block quantization parameter decoding unit 501 via the selector 500. The sub-block quantization parameter decoding unit 501 decodes using Golomb code and reproduces the sub-block quantization parameter. This sub-block quantization parameter is input to the basic block quantization parameter determination unit 504 via the selector 503. Since the subblock of the subblock quantization parameter is the first subblock of the first basic block, the basic block quantization parameter determination unit 504 holds the input as it is to obtain the basic block quantization parameter. Further, the sub-block quantization parameter reproduced by the sub-block quantization parameter decoding unit 501 is output from the terminal 106 via the selector 506. Further, the sub-block quantization parameter is held in the sub-block quantization parameter holding unit 507.

  Thereafter, the selector 500 sets the output destination as the sub-block quantization parameter difference value decoding unit 502, and the selector 503 sets the input destination as the sub-block quantization parameter holding unit 507. The selector 506 sets the input destination as the sub-block quantization parameter addition unit 305.

  When sub-block quantization parameter difference value encoded data of the subsequent sub-block is input, it is input to the sub-block quantization parameter difference value decoding unit 502 via the selector 500. Sub-block quantization parameter difference value decoding section 502 decodes the sub-block quantization parameter difference value encoded data and reproduces the sub-block quantization parameter difference value. The sub-block quantization parameter adding unit 305 adds the sub-block quantization parameter difference value to the basic block quantization parameter to reproduce the sub-block quantization parameter. The reproduced sub-block quantization parameter is output from terminal 106. Further, the sub-block quantization parameter is held in the sub-block quantization parameter holding unit 507.

  Sub block quantization parameter difference value encoded data of the subsequent basic block is input. At this time, the basic block quantization parameter determination unit 504 reads the sub block quantization parameter of the previous basic block from the sub block quantization parameter holding unit 507. An average value of the read sub-block quantization parameters is obtained and set as a basic block quantization parameter of the basic block.

  The input sub-block quantization parameter difference value encoded data is decoded by the sub-block quantization parameter difference value decoding unit 502 to reproduce the sub-block quantization parameter difference value. The sub-block quantization parameter adding unit 305 reproduces the sub-block quantization parameter, outputs it from the terminal 106, and holds it in the sub-block quantization parameter holding unit 507.

  Subsequently, the sub-block quantization parameter difference value is also reproduced in the same manner for the input sub-block quantization parameter difference value encoded data, and then the sub-block quantization parameter is reproduced. The reproduced sub-block quantization parameter is output from the terminal 106 and held in the sub-block quantization parameter holding unit 507.

  FIG. 19 is a flowchart illustrating an image decoding process in the image decoding apparatus according to the sixth embodiment.

  In step S101, header information is decoded as in the second embodiment. In step S501, it is determined whether or not the basic block of the sub-block to be decoded is the head of the image. If it is the head basic block, the process proceeds to step S502. Otherwise, the process proceeds to step S504.

In step S502, it is determined whether or not the sub-block to be decoded is the first sub-block of the basic block. If it is the first block, the process proceeds to step S503, and if not, the process proceeds to step S506. In step S503, the input code related to the sub-block quantization parameter is encoded data of the sub-block quantization parameter. This is decoded with Golomb code. The decoding result is held as a basic block quantization parameter. At the same time, it is stored separately for reference when determining the basic block quantization parameter of the next basic block. Thereafter, the process proceeds to step S104 to generate a decoded image of the first sub-block.
In step S504, it is determined whether or not the sub-block to be decoded is the first sub-block of the basic block. If it is the first block, the process proceeds to step S505, and if not, the process proceeds to step S506.

  In step S505, an average value is obtained from the sub-block quantization parameter of the previous basic block held and calculated as the basic block quantization parameter. Thereafter, the process proceeds to step S506.

  In step S506, the input code related to the sub-block quantization parameter is sub-block quantization parameter difference value encoded data. This is decoded with Golomb code to reproduce the sub-block quantization parameter difference value. The reproduced sub-block quantization parameter difference value is added to the basic block quantization parameter held or calculated in step S503 or step S505. The added result becomes a sub-block quantization parameter. Thereafter, the process proceeds to step S104 to generate a decoded image of the sub-block. Thereafter, similarly to the fourth embodiment, generation of a decoded image of a sub-block and reproduction of a frame image are performed.

  With the above configuration and operation, it is possible to decode a bitstream that does not encode the basic block quantization parameter value generated in the fifth embodiment.

  Further, it is possible to effectively perform parallel processing as in the second embodiment. That is, in FIG. 9B, instead of decoding the basic block quantization parameter of the processor A, it is replaced with calculation of the basic block quantization parameter by the sub-block quantization parameter of the previous basic block. As a result, the quantization parameters of all the sub blocks can be reproduced without waiting for the processing of other sub blocks.

  In the present embodiment, the basic block quantization parameter is an average value of the sub-block quantization parameters of the previous basic block. However, if the same method as the calculation method of the basic block quantization parameter of the fifth embodiment is used, this is used. It is not limited. For example, it may be the median value of the sub-blocks, or of course the value of the most frequently used sub-block quantization parameter. Such information can be derived from the sub-block quantization parameters held in the sub-block quantization parameter holding unit 507.

  Moreover, even if a plurality of calculation methods are prepared in this way on the encoding side, the most efficient basic block quantization parameter is selected, and encoding is performed using a code representing the method, the subblock quantum is similarly decoded. Parameter can be calculated.

In the present embodiment, a frame using intra prediction has been described as an example. However, it is clear that the present invention can also be applied to a frame that can use inter prediction that performs motion compensation for prediction. <Embodiment 7>
In the above embodiment, the processing units shown in FIGS. 1, 3, 6, 7, 10, 11, 13, 14, 16, and 18 are configured by hardware. explained. However, the processing performed by each processing unit shown in these figures may be configured by a computer program.

  FIG. 20 is a block diagram illustrating a configuration example of computer hardware applicable to the image display device according to each of the above embodiments.

  The CPU 1401 controls the entire computer using computer programs and data stored in the RAM 1402 and the ROM 1403, and executes each process described above as performed by the image processing apparatus according to each of the above embodiments. That is, the CPU 1401 functions as each processing unit shown in FIGS. 1, 3, 6, 7, 10, 11, 13, 14, 16, and 18.

  The RAM 1402 has an area for temporarily storing computer programs and data loaded from the external storage device 1406, data acquired from the outside via an I / F (interface) 1409, and the like. Further, the RAM 1402 has a work area used when the CPU 1401 executes various processes. That is, the RAM 1402 can be allocated as, for example, a frame memory or can provide other various areas as appropriate.

  The ROM 1403 stores setting data of the computer, a boot program, and the like. The operation unit 1404 is configured by a keyboard, a mouse, and the like, and can input various instructions to the CPU 1401 when operated by a user of the computer. A display unit 1405 displays a processing result by the CPU 1401. The display unit 1405 is configured by a hold type display device such as a liquid crystal display or an impulse type display device such as a field emission type display device.

  The external storage device 1406 is a mass information storage device represented by a hard disk drive device. The external storage device 1406 has an OS (operating system) and functions of each unit shown in FIGS. 1, 3, 6, 7, 10, 10, 11, 13, 16, and 18. A computer program to be realized by the CPU 1401 is stored. Further, each image data as a processing target may be stored in the external storage device 1406.

  Computer programs and data stored in the external storage device 1406 are appropriately loaded into the RAM 1402 under the control of the CPU 1401 and are processed by the CPU 1401. The I / F 1407 can be connected to a network such as a LAN or the Internet, and other devices such as a projection device and a display device. The computer can acquire and send various information via the I / F 1407. Can be. A bus 1408 connects the above-described units.

  The operation having the above-described configuration is controlled by the CPU 1401 as the operation described in the above flowchart.

  When the CPU is multi-core, parallel processing can be performed efficiently by assigning each processing thread to each core.

<Other embodiments>
The object of the present invention can also be achieved by supplying a storage medium storing a computer program code for realizing the above-described functions to the system, and the system reading and executing the computer program code. In this case, the computer program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the computer program code constitutes the present invention. In addition, the operating system (OS) running on the computer performs part or all of the actual processing based on the code instruction of the program, and the above-described functions are realized by the processing. .

  Furthermore, you may implement | achieve with the following forms. That is, the computer program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer. Then, based on the instruction of the code of the computer program, the above-described functions are realized by the CPU or the like provided in the function expansion card or function expansion unit performing part or all of the actual processing.

  When the present invention is applied to the above storage medium, the computer program code corresponding to the flowchart described above is stored in the storage medium.

Claims (6)

An image encoding device for quantizing an image in units of blocks,
A first quantization parameter blocks that are included in the image, the encompassed in the image, the a difference value between the quantization parameter of the second block to be coded after the first block 1 difference values, and a third quantization parameter blocks that are included in the image, at least two blocks to be encoded prior to the third block of the plurality of blocks included in the image Acquisition means for acquiring a second difference value that is a difference value from the average of the quantization parameter of
Encoding means for encoding the first difference value and the second difference value acquired by the acquisition means;
An image encoding apparatus comprising: An image decoding device that decodes code data for quantizing an image in units of blocks, wherein code data relating to a difference value between a quantization parameter of a block included in the image and a predetermined parameter among the code data Decoding means for decoding
The block included in the image is encoded after the first block by adding the quantization parameter of the first block as the predetermined parameter and the difference value acquired by the decoding unit A quantization parameter of the second block that is generated, and the predetermined parameter is an average of quantization parameters of at least two blocks that are blocks before the third block in the image. Obtaining means for obtaining the quantization parameter of the third block by adding the difference value obtained by the decoding means;
An image decoding apparatus comprising: An image encoding method for quantizing an image in units of blocks,
A first difference that is a difference value between a quantization parameter of a first block included in the image and a quantization parameter of a second block included in the image and encoded after the first block A value, a quantization parameter of a third block included in the image, and an average of quantization parameters of at least two blocks encoded before the third block among a plurality of blocks in the image An acquisition step of acquiring a second difference value that is a difference value between
An encoding step of encoding the first difference value and the second difference value acquired by the acquisition step;
An image encoding method characterized by comprising: An image decoding method for decoding code data for quantizing an image in units of blocks,
A decoding step of decoding code data related to a difference value between a quantization parameter of a block included in the image and a predetermined parameter among the code data;
The block included in the image is encoded after the first block by adding the quantization parameter of the first block as the predetermined parameter and the difference value acquired by the decoding step A quantization parameter of the second block that is generated, and the predetermined parameter is an average of quantization parameters of at least two blocks that are blocks before the third block in the image. Acquiring the quantization parameter of the third block by adding the difference value acquired in the decoding step;
An image decoding method characterized by comprising: A program that causes a computer to function as the image encoding device according to claim 1 by being read and executed by the computer. A program that causes the computer to function as the image decoding device according to claim 2 by being read and executed by the computer.

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