JP2009177357A - Encoder and encoding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce an operation amount for selecting a prediction mode in intra prediction. <P>SOLUTION: First, a SAD is calculated for the prediction mode 0 in which a prediction direction is a vertical direction, and the prediction mode 1 in which the prediction direction is a horizontal direction. Then, a SAD of the prediction mode in the prediction direction to be close to the prediction direction of the smaller SAD is calculated, and the sizes of the SADs are compared. By narrowing the prediction direction by repeating such processing and determining the prediction mode, the operation amount for selecting the prediction mode is reduced. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an encoding device, an encoding method, a program, and a recording medium. The present invention relates to a technique suitable for use in H.264 intra prediction.

  In order to encode moving image data having a huge amount of data compared to still image data, an encoding method such as MPEG-2 (Moving Picture Experts Group phase 2) method has been established. Many imaging devices such as digital cameras and digital video cameras capable of recording moving image data using these encoding methods have been commercialized by manufacturers.

  In recent years, manufacturers have commercialized products that can record moving image data of larger image sizes such as higher definition (HD) images and full HD images compared to conventional SD (Standard Definition) images. Yes. Thus, the amount of data increases due to the enlargement of the image size.

  Therefore, ITU-T (International Telecommunication Union Telecommunication Standardization Sector) and ISO (International Organization for Standardization) An encoding method called H.264 / MPEG-4 part 10 (hereinafter referred to as H.264) has been standardized. H. The H.264 system can achieve higher compression than the conventional encoding system such as the MPEG-2 system. This H. For example, Patent Document 1 discloses the configuration of the H.264 arithmetic processing.

JP 2004-56827 A

  H. In the H.264 method, a prediction method called intra prediction that improves compression efficiency by predicting pixel values in the same screen using encoded pixel values in the screen (frame) is defined. H. In the H.264 intra prediction, a pixel block unit for generating a prediction image for performing an encoding process can be selected from a 16 × 16 pixel block unit, an 8 × 8 pixel block unit, and a 4 × 4 pixel block unit.

  In addition, H.C. In the H.264 system, a plurality of prediction modes are defined for each pixel block unit. By selectively using these pixel block units and prediction modes according to the input image, encoded data with high encoding efficiency can be generated. For example, in intra prediction performed in units of 4 × 4 pixel blocks, nine prediction modes having different prediction directions are defined.

  Here, as a prediction mode selection method, calculation such as prediction image generation is performed in all prediction modes, and a prediction mode that realizes optimal coding efficiency is selected from the nine prediction modes based on the result for each prediction mode. The method of selection is common. In this way, the calculation is performed for all the prediction modes of the specified prediction mode.

  Therefore, H.H. The H.264 system can achieve high compression compared to a conventional encoding system such as the MPEG-2 system, but the amount of calculation is larger. For this reason, there has been a problem that the power consumption increases as the amount of calculation increases.

  In view of the above-described problems, an object of the present invention is to reduce the amount of calculation for selecting a prediction mode in intra prediction.

  An encoding apparatus according to the present invention is an encoding apparatus that performs an encoding process by dividing an input image into a predetermined block size, and uses a pixel value of a block adjacent to an encoding target block having the predetermined block size. A prediction image generation unit that generates a prediction image of the encoding target block in a predetermined prediction mode; and a difference value that calculates a difference value between the prediction image generated by the prediction image generation unit and the encoding target block The calculation means, a first selection means for selecting a prediction mode that minimizes the difference value calculated by the difference value calculation means from two or more prediction modes, and the first selection means selected by the first selection means The difference value calculated by the difference value calculation means is the highest among the two or more prediction modes including the prediction mode in the prediction direction that is close to the prediction direction of the prediction mode. Select the prediction mode become, characterized in that a second selection means for determining a prediction mode for performing the coding process.

  An encoding method according to the present invention is an encoding method for performing an encoding process by dividing an input image into a predetermined block size, and uses a pixel value of a block adjacent to an encoding target block having the predetermined block size. A prediction image generation step for generating a prediction image of the encoding target block in a predetermined prediction mode, and a difference value calculation for calculating a difference value between the prediction image generated in the prediction image generation step and the encoding target block A first selection step of selecting a prediction mode that minimizes the difference value calculated in the difference value calculation step from among the two or more prediction modes, and the prediction mode selected in the first selection step The difference value calculated in the difference value calculation step is minimized from two or more prediction modes including a prediction mode in a prediction direction that is close to the prediction direction. Select measurement mode, is characterized in that a second selection step of determining a prediction mode for performing the coding process.

  The program of the present invention is a program that causes a computer to execute each step of an encoding method for performing an encoding process by dividing an input image into a predetermined block size, and is adjacent to an encoding target block having the predetermined block size. A prediction image generation step of generating a prediction image of the encoding target block in a predetermined prediction mode using a pixel value of the block to be performed, and a difference between the prediction image generated in the prediction image generation step and the encoding target block A difference value calculation step of calculating a value, a first selection step of selecting a prediction mode in which the difference value calculated in the difference value calculation step is the minimum from two or more prediction modes, and the first selection The difference between two or more prediction modes including a prediction mode in a prediction direction that is close to the prediction direction of the prediction mode selected in the process. Select the prediction mode difference value calculated in the calculating step is minimized, characterized in that to execute a second selection step of determining a prediction mode for performing the encoding process on the computer.

  The recording medium of the present invention is characterized by recording the program described above.

  According to the present invention, a prediction mode with a minimum difference value is selected, and a difference value is further calculated from two or more prediction modes including a prediction mode in a prediction direction that is close to the prediction direction of the selected prediction mode. The prediction mode that minimizes was selected. Thereby, since it can narrow down to an appropriate prediction direction by selection of prediction mode, the amount of calculations for selecting a prediction mode in intra prediction can be reduced. Therefore, power consumption can be reduced.

(First embodiment)
Preferred embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram illustrating a configuration example of a moving image encoding apparatus according to the present embodiment.
In FIG. 1, the difference calculation unit 101 calculates a difference value between the input image input to the video encoding device 100 and the predicted image generated by the determined predicted image generation unit 109. A method for generating a predicted image will be described later.

  Next, the orthogonal transform / quantization unit 102 converts the difference value data between the input image and the prediction image output from the difference calculation unit 101 into an integer precision discrete cosine transform and an 8 × 8 or 4 × 4 pixel block unit. Perform orthogonal transform processing by discrete Hadamard transform. Then, quantization processing is performed on the data after orthogonal transformation, and the data is output to the entropy coding unit 103.

  Next, the entropy encoding unit 103 performs entropy encoding processing on the input quantized data and outputs encoded data. The encoding is performed using CAVLC (Context-based Adaptive Variable Length Coding) or CABAC (Context-based Adaptive Binary Asymmetric Coding).

  Next, a process for generating a predicted image will be described. The inverse quantization / inverse orthogonal transformation unit 104 performs inverse quantization processing and inverse orthogonal transformation processing on the quantized data output from the orthogonal transformation / quantization unit 102. Further, the data obtained by adding the predicted images output from the determined predicted image generation unit 109 is output to the deblocking filter processing unit 105 and the first memory 106.

  In addition, the deblocking filter processing unit 105 performs deblocking filter processing on the input data and stores the data in the second memory 107. That is, the data before the deblocking filter process is stored in the first memory 106, and the data after the deblocking filter process is stored in the second memory 107.

  Next, the prediction method determination unit 108 determines the prediction method of the prediction image using the data stored in the first memory 106 and the second memory 107 and the input image. In intra-screen prediction (intra prediction), encoding efficiency is obtained using data before deblocking filter processing stored in the first memory 106. Specifically, the encoding efficiency is obtained for each unit of a predetermined block size (16 × 16 pixel block unit, 8 × 8 pixel block unit, 4 × 4 pixel block unit) and for each predetermined prediction mode.

  On the other hand, for inter-screen prediction (inter prediction), the coding efficiency is obtained using the data after the deblocking filter processing stored in the second memory 107 and the input image. In this way, the prediction method that optimizes the encoding efficiency is determined. When the input image is an I slice, only intra prediction is adopted, and when the input image is a P slice and B slice, a prediction method that provides optimum coding efficiency is selected from intra prediction and inter prediction.

  Through the above processing, the prediction method determination unit 108 outputs the prediction method and the encoding parameter with the optimum encoding efficiency to the determined predicted image generation unit 109. The determined predicted image generation unit 109 generates a predicted image according to the prediction method determined by the prediction method determination unit 108.

  Next, the detailed configuration of the prediction method determination unit 108 illustrated in FIG. 1 will be described in detail with reference to FIG. In FIG. 2, the prediction method determination unit 201, the first memory 207, and the second memory 208 have the same configurations as the prediction method determination unit 108, the first memory 106, and the second memory 107 shown in FIG. It is.

  In the in-screen prediction mode determination unit 202, the prediction mode selection unit 203 selects a plurality of prediction modes from the specified prediction modes in a predetermined pixel block unit. At this time, the luminance signal is performed in units of 16 × 16 pixel blocks, 8 × 8 pixel blocks, or 4 × 4 pixel blocks, and the color difference signal is performed in units of 8 × 8 pixel blocks.

  Here, the prescribed prediction mode will be described. FIG. 3 is a diagram illustrating a prediction mode in units of 16 × 16 pixel blocks in the luminance signal, and FIG. 4 is a diagram illustrating a prediction mode in units of 8 × 8 pixel blocks in the luminance signal. FIG. 5 is a diagram showing a prediction mode in units of 4 × 4 pixel blocks in the luminance signal. Further, FIG. 6 is a diagram illustrating a prediction mode in units of 8 × 8 pixel blocks in the color difference signal.

  As shown in FIGS. 3 to 6, nine prediction modes are defined for the 8 × 8 pixel block unit and the 4 × 4 pixel block unit of the luminance signal, and the 16 × 16 pixel block unit of the luminance signal and the 8 of the color difference signal. For the × 8 pixel block unit, four prediction modes are defined.

  Next, the prediction image generation unit 204 reads out the pixel values of adjacent blocks located on the left, upper, upper right, and upper left of the encoding target block from the first memory 207, and the prediction mode selected by the prediction mode selection unit 203 A prediction image is generated for each time. Next, the difference value calculation unit 205 calculates a difference value between pixel values between the predicted image generated by the predicted image generation unit 204 and an input image input from the outside. Further, the sum of absolute values of the difference values (SAD: Sum of Absolute Difference) is calculated for each pixel block.

  Next, the SAD comparison unit 206 compares the SAD for each prediction mode selected by the prediction mode selection unit 203, determines that the prediction mode with the smallest SAD is a prediction mode with high coding efficiency, and performs prediction. The mode result is sent to the prediction mode selection unit 203. In the present embodiment, the SAD comparison unit 206 first functions as a first selection unit, selects a prediction mode with a small SAD from among the prediction modes in the horizontal direction and the vertical direction, and outputs a prediction mode result to the prediction mode selection unit 203. Send to. Then, the prediction mode selection unit 203 selects a prediction mode in the prediction direction that is close to the prediction mode result output from the SAD comparison unit 206. Thereafter, the SAD comparison unit 206 functions as the second selection unit and repeats the comparison in the same manner to determine the optimal prediction mode, and the result is output to the outside of the in-screen prediction mode determination unit 202 via the prediction mode selection unit 203. Is output. A specific processing procedure for determining the optimum prediction mode will be described later.

  Next, the encoding method comparison unit 210 compares the result output from the intra prediction mode determination unit 202 with the result output from the inter prediction method determination unit 209 to encode the encoding target block. Decide how. At this time, the comparison is performed when the input image is H.264. This is a case of P slice or B slice in the H.264 system. In the case where only intra prediction is valid as in the case of I slice, the result output from the intra prediction mode determination unit 202 is output to the outside of the prediction method determination unit 201.

Next, a processing procedure for determining a prediction mode in intra prediction in units of 4 × 4 pixel blocks of luminance signals will be described with reference to flowcharts of FIGS. 7-1 and 7-2.
First, in step S701, the difference value calculation unit 205 calculates SAD for the prediction mode 0 in which the prediction direction is the vertical direction and the prediction mode 1 in which the prediction direction is the horizontal direction as shown in FIG.

  Next, in step S <b> 702, the SAD comparison unit 206 compares the SAD calculation results of the prediction mode 0 and the prediction mode 1. As a result of the comparison, if the result of the prediction mode 1 is better, the process proceeds to step S703. If the result of the prediction mode 0 is better, or if the two results are equal, the process proceeds to step S724. In step S703, the difference value calculation unit 205 calculates SAD for prediction modes 6 and 8 that are close to the horizontal direction, which is the prediction direction of prediction mode 1, as shown in FIG.

  Next, in step S <b> 704, the SAD comparison unit 206 compares the SAD calculation results for the prediction mode 1, the prediction mode 6, and the prediction mode 8. As a result of the comparison, if the result of the prediction mode 8 is better than the other two prediction modes, the process proceeds to step S705, and otherwise, the process proceeds to step S709.

  Next, in step S705, the difference value calculation unit 205 calculates SAD for the prediction mode 2 in which there is no prediction direction and the predicted image is generated based on the average value of the neighboring block pixels. In step S706, the SAD comparison unit 206 compares the SAD calculation results of the prediction mode 2 and the prediction mode 8. As a result of this comparison, if the result of the prediction mode 8 is better, the process proceeds to step S707, the prediction mode of the block to be encoded is determined as the prediction mode 8, and the process is terminated. On the other hand, as a result of the comparison in step S706, if the result of prediction mode 2 is better, or if the two results are equal, the process proceeds to step S708, and the prediction mode of the encoding target block is determined to be prediction mode 2, The process ends.

  On the other hand, if the result of comparison in step S704 shows that the result of prediction mode 8 is better than the other two prediction modes, conditional branching is further performed in step S709. That is, the SAD comparison unit 206 further compares the SAD calculation results of the prediction mode 1 and the prediction mode 6. As a result of this comparison, if the result of the prediction mode 6 is the best, the process proceeds to step S710, and otherwise, the process proceeds to step S720.

  In step S <b> 710, the difference value calculation unit 205 calculates SAD for the prediction mode 4 close to the prediction direction of the prediction mode 6. Since the other prediction mode 1 near the prediction direction of the prediction mode 6 has already been calculated / compared, the SAD is calculated only for the prediction mode 4 in step S710.

  Next, in step S <b> 711, the SAD comparison unit 206 compares the SAD calculation results of the prediction mode 4 and the prediction mode 6. As a result of this comparison, if the result of the prediction mode 6 is better, the process proceeds to step S712, otherwise the process proceeds to step S716.

  In step S712, the difference value calculation unit 205 calculates the SAD of the prediction mode 2 described above. In step S713, the SAD comparison unit 206 compares the SAD calculation results of the prediction mode 2 and the prediction mode 6. As a result of the comparison, if the result of the prediction mode 6 is better, the process proceeds to step S714, the prediction mode of the block to be encoded is determined to be the prediction mode 6, and the process ends. On the other hand, as a result of the comparison in step S713, if the result of the prediction mode 2 is better, or if the two results are equal, the process proceeds to step S715 to determine the prediction mode of the block to be encoded as the prediction mode 2, and the processing Exit.

  On the other hand, as a result of the comparison in step S711, if the result of the prediction mode 4 is better, or if the two results are equal, the process proceeds to step S716, and the difference value calculation unit 205 calculates the SAD of the prediction mode 2. In step S717, the SAD comparison unit 206 compares the SAD calculation results in the prediction mode 2 and the prediction mode 4.

  As a result of the comparison, if the result of the prediction mode 4 is better, the process proceeds to step S718, the prediction mode of the block to be encoded is determined to be the prediction mode 4, and the process ends. On the other hand, as a result of the comparison in step S717, if the result of the prediction mode 2 is better, or if the two results are equal, the process proceeds to step S719, and the prediction mode of the encoding target block is determined to be the prediction mode 2, and the process Exit.

  On the other hand, as a result of the comparison in step S709, if the result of the prediction mode 8 is better, or if the two results are equal, the process proceeds to step S720, and the difference value calculation unit 205 calculates the SAD of the prediction mode 2. In step S721, the SAD comparison unit 206 compares the SAD calculation results of the prediction mode 1 and the prediction mode 2.

  As a result of the comparison, if the result of the prediction mode 2 is better, the process proceeds to step S722, the prediction mode of the block to be encoded is determined to be the prediction mode 2, and the process ends. On the other hand, as a result of the comparison in step S721, if the result of the prediction mode 1 is better, or if the two results are equal, the process proceeds to step S723, and the prediction mode of the block to be encoded is determined as the prediction mode 1, and the process Exit.

  On the other hand, as a result of the comparison in step S702, if the result of the prediction mode 0 is better, or if the two results are equal, the process proceeds to step S724. In step S724, the difference value calculation unit 205 calculates SAD for prediction mode 5 and prediction mode 7 close to the vertical direction, which is the prediction direction of prediction mode 0, as shown in FIG.

  Next, in step S725, the SAD comparison unit 206 compares the SAD calculation results of the prediction mode 0, the prediction mode 5, and the prediction mode 7. As a result of the comparison, when the result of the prediction mode 7 is better than the other two prediction modes, the process proceeds to step S726. In step S <b> 726, the difference value calculation unit 205 calculates the SAD of the prediction mode 3 that is close to the prediction direction of the prediction mode 7.

  Next, in step S727, the SAD comparison unit 206 compares the SAD calculation results of the prediction mode 3 and the prediction mode 7. As a result of the comparison, when the result of the prediction mode 7 is better, the process proceeds to step S728, and the difference value calculation unit 205 calculates the SAD of the prediction mode 2.

  In step S729, the SAD comparison unit 206 compares the SAD calculation results of the prediction mode 2 and the prediction mode 7. As a result of this comparison, if the result of the prediction mode 7 is better, the process proceeds to step S730, the prediction mode of the block to be encoded is determined to be the prediction mode 7, and the process ends. On the other hand, as a result of the comparison in step S729, if the result of the prediction mode 2 is better, or if the two results are equal, the process proceeds to step S731, and the prediction mode of the encoding target block is determined to be the prediction mode 2, and the process Exit.

  On the other hand, if the result of the comparison in step S727 is better than the result of the prediction mode 3, or if the two results are equal, the process proceeds to step S732, and the difference value calculation unit 205 calculates the SAD of the prediction mode 2. In step S733, the SAD comparison unit 206 compares the SAD calculation results of the prediction mode 2 and the prediction mode 3.

  As a result of the comparison, if the result of the prediction mode 3 is better, the process proceeds to step S734, the prediction mode of the block to be encoded is determined to be the prediction mode 3, and the process ends. On the other hand, if the result of the prediction mode 2 is better or the two results are equal as a result of the comparison in step S733, the process proceeds to step S735, and the prediction mode of the encoding target block is determined to be the prediction mode 2, and the process Exit.

  On the other hand, if the result of comparison in step S725 shows that the result of prediction mode 7 is better than the other two prediction modes, conditional branching is further performed in step S736. That is, the SAD comparison unit 206 further compares the SAD calculation results of the prediction mode 0 and the prediction mode 5. As a result of the comparison, if the result of the prediction mode 5 is better, the process proceeds to step S737, and the difference value calculation unit 205 calculates the SAD of the prediction mode 4.

  Next, in step S738, the SAD comparison unit 206 compares the SAD calculation results of the prediction mode 4 and the prediction mode 5. As a result of the comparison, if the result of the prediction mode 5 is better, the process proceeds to step S739, and the difference value calculation unit 205 calculates the SAD of the prediction mode 2.

  In step S740, the SAD comparison unit 206 compares the SAD calculation results of the prediction mode 2 and the prediction mode 5. As a result of the comparison, if the result of the prediction mode 5 is better, the process proceeds to step S741, the prediction mode of the block to be encoded is determined to be the prediction mode 5, and the process ends. On the other hand, as a result of the comparison in step S740, if the result of prediction mode 2 is better, or if the two results are equal, the process proceeds to step S742, and the prediction mode of the block to be encoded is determined to be prediction mode 2, and the process Exit.

  On the other hand, when the result of the prediction mode 4 is better or the two results are equal as a result of the comparison in step S738, the process proceeds to step S743, and the difference value calculation unit 205 calculates the SAD of the prediction mode 2. In step S744, the SAD comparison unit 206 compares the SAD calculation results of the prediction mode 2 and the prediction mode 4.

  As a result of the comparison, if the result of the prediction mode 4 is better, the process proceeds to step S745, the prediction mode of the block to be encoded is determined to be the prediction mode 4, and the process ends. On the other hand, when the result of the prediction mode 2 is better or the two results are equal as a result of the comparison in step S744, the process proceeds to step S746, and the prediction mode of the encoding target block is determined to be the prediction mode 2, and the process Exit.

  On the other hand, as a result of the comparison in step S736, if the result of the prediction mode 0 is better, or if the two results are equal, the process proceeds to step S747. In step S747, the difference value calculation unit 205 calculates the SAD of the prediction mode 2.

  Next, in step S748, the SAD comparison unit 206 compares the SAD calculation results of the prediction mode 0 and the prediction mode 2. As a result of the comparison, if the result of the prediction mode 2 is better, the process proceeds to step S749, the prediction mode of the block to be encoded is determined as the prediction mode 2, and the process ends. On the other hand, as a result of the comparison in step S748, if the result of the prediction mode 0 is better, or if the two results are equal, the process proceeds to step S750, and the prediction mode of the encoding target block is determined to be the prediction mode 0, and the process Exit.

  As described above, in the present embodiment, a prediction image can be determined by generating a prediction image for five or six prediction modes out of nine prediction modes and calculating SAD. As a result, the amount of calculation until the prediction mode is determined can be reduced, and the power consumption can be reduced.

  In the present embodiment, SAD is used to determine the coding efficiency for each prediction mode. On the other hand, other conditions such as SATD (Sum of Absolute Transform Difference) which is the sum of absolute values of coefficients obtained by adding frequency conversion processing to the difference value for each pixel may be used.

  In the present embodiment, the 4 × 4 pixel block unit of the luminance signal has been described. However, the present invention can be realized under other conditions, such as the 8 × 8 pixel block unit of the luminance signal.

  Furthermore, in the present embodiment, for the prediction mode determination process for intra prediction, a predicted image is generated from data before the deblocking filter process, but for example, data of the current image may be used.

  In the present embodiment, processing is first performed by comparing the prediction mode 0 in the vertical direction and the prediction mode 1 in the horizontal direction. On the other hand, for example, when the comparison is started from three prediction modes to which another prediction mode is added, or when the comparison is started from another two prediction modes, another pattern may be used.

(Other embodiments according to the present invention)
Each means constituting the encoding apparatus and each step of the encoding method in the embodiment of the present invention described above can be realized by operating a program stored in a RAM or ROM of a computer. This program and a computer-readable recording medium recording the program are included in the present invention.

  In addition, the present invention can be implemented as, for example, a system, apparatus, method, program, or recording medium. Specifically, the present invention may be applied to a system including a plurality of devices. The present invention may be applied to an apparatus composed of a single device.

  In the present invention, a software program that realizes the functions of the above-described embodiments (in the embodiment, a program corresponding to the flowcharts shown in FIGS. 7-1 and 7-2) is directly or remotely transmitted to a system or apparatus. Including the case of supply. This includes the case where the system or the computer of the apparatus is also achieved by reading and executing the supplied program code.

  Accordingly, since the functions of the present invention are implemented by computer, the program code installed in the computer also implements the present invention. In other words, the present invention includes a computer program itself for realizing the functional processing of the present invention.

  In that case, as long as it has the function of a program, it may be in the form of object code, a program executed by an interpreter, script data supplied to the OS, and the like.

  Examples of the recording medium for supplying the program include a flexible disk, a hard disk, an optical disk, and a magneto-optical disk. Further, there are MO, CD-ROM, CD-R, CD-RW, magnetic tape, nonvolatile memory card, ROM, DVD (DVD-ROM, DVD-R) and the like.

  As another program supply method, there is a method of connecting to a homepage on the Internet using a browser of a client computer. The computer program itself of the present invention or a compressed file including an automatic installation function can be downloaded from the homepage by downloading it to a recording medium such as a hard disk.

  It can also be realized by dividing the program code constituting the program of the present invention into a plurality of files and downloading each file from a different homepage. That is, a WWW server that allows a plurality of users to download a program file for realizing the functional processing of the present invention on a computer is also included in the present invention.

  As another method, the program of the present invention is encrypted, stored in a recording medium such as a CD-ROM, distributed to users, and encrypted from a homepage via the Internet to users who have cleared predetermined conditions. Download the key information to be solved. It is also possible to execute the encrypted program by using the key information and install the program on a computer.

  Further, the functions of the above-described embodiments are realized by the computer executing the read program. Furthermore, based on the instructions of the program, an OS or the like running on the computer performs part or all of the actual processing, and the functions of the above-described embodiments can be realized by the processing.

  As another method, the program read from the recording medium is first written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Then, based on the instructions of the program, the CPU or the like provided in the function expansion board or function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are also realized by the processing.

It is a block diagram which shows the structural example of the moving image encoder which concerns on embodiment of this invention. It is a block diagram which shows the example of an internal structure of the prediction method determination part in embodiment of this invention. It is a figure which shows the prediction mode in a screen in a 16x16 pixel block unit of a luminance signal. It is a figure which shows the prediction mode in a screen in the unit of 8x8 pixel block of a luminance signal. It is a figure which shows the prediction mode in a screen in the 4x4 pixel block unit of a luminance signal. It is a figure which shows the prediction mode in a screen in the unit of 8x8 pixel block of a color difference signal. 5 is a flowchart illustrating an example of a processing procedure for determining a prediction mode in intra prediction in units of 4 × 4 pixel blocks of luminance signals in the embodiment of the present invention. 5 is a flowchart illustrating an example of a processing procedure for determining a prediction mode in intra prediction in units of 4 × 4 pixel blocks of luminance signals in the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Moving image encoding apparatus 101 Difference calculation part 102 Orthogonal transformation / quantization part 103 Entropy encoding part 104 Inverse quantization / inverse orthogonal transformation part 105 Deblocking filter process part 106 1st memory 107 2nd memory 108 Prediction method Determination unit 109 Determination prediction image generation unit 201 Prediction direction determination unit 202 In-screen prediction mode determination unit 203 Prediction mode selection unit 204 Prediction image generation unit 205 Difference value calculation unit 206 SAD comparison unit 207 First memory 208 Second memory 209 Inter-screen prediction method determination unit 210 Encoding method comparison unit

Claims (8)

An encoding device that performs an encoding process by dividing an input image into a predetermined block size,
Prediction image generation means for generating a prediction image of the encoding target block in a predetermined prediction mode using a pixel value of a block adjacent to the encoding target block of the predetermined block size;
Difference value calculating means for calculating a difference value between the predicted image generated by the predicted image generating means and the encoding target block;
First selection means for selecting a prediction mode that minimizes the difference value calculated by the difference value calculation means from among two or more prediction modes;
The difference value calculated by the difference value calculation unit is selected from two or more prediction modes including a prediction mode in a prediction direction that is close to the prediction direction of the prediction mode selected by the first selection unit. An encoding apparatus comprising: a second selection unit that selects a prediction mode that minimizes and determines a prediction mode for performing the encoding process.   The encoding apparatus according to claim 1, wherein the prediction mode selected by the first selection means is a prediction mode in a vertical direction or a horizontal direction.   The said 2nd selection means determines the prediction mode for performing the said encoding process by repeating the process which selects the prediction mode with a small difference value from two prediction modes, It is characterized by the above-mentioned. The encoding device described. An encoding method that performs an encoding process by dividing an input image into a predetermined block size,
A prediction image generation step of generating a prediction image of the encoding target block in a predetermined prediction mode using a pixel value of a block adjacent to the encoding target block of the predetermined block size;
A difference value calculation step of calculating a difference value between the prediction image generated in the prediction image generation step and the encoding target block;
A first selection step of selecting a prediction mode that minimizes the difference value calculated in the difference value calculation step from two or more prediction modes;
The difference value calculated in the difference value calculation step is the smallest among two or more prediction modes including the prediction mode in the prediction direction that is close to the prediction direction of the prediction mode selected in the first selection step. And a second selection step of determining a prediction mode for performing the encoding process.   The encoding method according to claim 4, wherein the prediction mode selected in the first selection step is a prediction mode in a vertical direction or a horizontal direction.   6. The prediction mode for performing the encoding process is determined by repeating a process of selecting a prediction mode having a small difference value from two prediction modes in the second selection step. The encoding method described in 1. A program for causing a computer to execute each step of an encoding method for performing an encoding process by dividing an input image into a predetermined block size,
A prediction image generation step of generating a prediction image of the encoding target block in a predetermined prediction mode using a pixel value of a block adjacent to the encoding target block of the predetermined block size;
A difference value calculation step of calculating a difference value between the prediction image generated in the prediction image generation step and the encoding target block;
A first selection step of selecting a prediction mode that minimizes the difference value calculated in the difference value calculation step from two or more prediction modes;
The difference value calculated in the difference value calculation step is the smallest among two or more prediction modes including the prediction mode in the prediction direction that is close to the prediction direction of the prediction mode selected in the first selection step. And a second selection step for determining a prediction mode for performing the encoding process.   A computer-readable recording medium, wherein the program according to claim 7 is recorded.

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