JP2004215296A - Image predictive encoding method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To more efficiently encode image data by removing redundancy within a block in comparison with conventional technology. <P>SOLUTION: Image data divided into blocks are converted into conversion coefficients of two-dimensional columns, the converted conversion coefficients of the two-dimensional columns are quantized to obtain quantized conversion coefficients. A predictive block to predict a quantized DC coefficient of the current block is adaptively selected from either an upper block or a left block adjacent to the current block, and the quantized DC coefficient of the current block is predicted from the quantized DC coefficient of the adjacent block adaptively selected from either the upper block or the left block, to find a DC coefficient predictive error. A quantized AC coefficient of the current block is predicted from a quantized AC coefficient of the block selected for DC coefficient prediction, to find an AC coefficient predictive error. Variable length encoding is applied to the DC coefficient predictive error and the AC coefficient predictive error. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to an image prediction encoding apparatus and method, an image prediction decoding apparatus and method, and a recording medium. In particular, an image prediction encoding apparatus and method, and an image prediction decoding apparatus and method for storing digital image data of an image as a still image or a moving image on a recording medium such as an optical disk or transmitting the communication line. About. Further, the present invention relates to a recording medium on which a program including the steps of the image prediction encoding method is recorded and a recording medium on which a program including the steps of the image prediction decoding method is recorded.

  For efficient storage or transmission of digital images, compression encoding is required. As a method for compressing and encoding a digital image, in addition to discrete cosine transform (hereinafter, referred to as DCT transform) represented by JPEG (Joint Photographic Experts Group) and MPEG (Motion Picture Experts Group), subband encoding is used. , Wavelet coding, and fractal coding. To remove redundant signals between images, inter-image prediction using motion compensation is performed, and the difference signal is waveform-encoded.

  In the MPEG system, an input image is divided into a plurality of 16 × 16 macroblocks and processed. One macroblock is further divided into 8 × 8 blocks, subjected to 8 × 8 DCT transform processing, and then quantized. This is called intra-frame coding.

  On the other hand, a motion detection method including block matching detects a predicted macroblock having the smallest error in the target macroblock from another frame adjacent to the time, and subtracts the detected predicted macroblock from the target macroblock. Then, a difference macroblock is generated, subjected to 8 × 8 DCT transform, and then quantized. This is called inter-frame coding, and the predicted macroblock is called a time-domain predicted signal. As described above, MPEG does not predict an image from the same frame.

  An ordinary image has many spatially similar regions, and by using this property, an image can be approximated to a spatial region. Similarly to the prediction signal in the time domain, the prediction signal can be obtained from the same frame. This is called a spatial domain prediction signal.

  Since two spatially close pixel values are close, the prediction signal in the spatial domain is generally located at a position close to the target signal. On the other hand, on the receiving side or the reproducing side, since there is no original image, it is necessary to use a signal encoded and reproduced in the past as the prediction signal. From these two factors, it is necessary to generate a spatial domain prediction signal at high speed. This is because the pixel value is used to generate a prediction signal immediately after decoding and reproduction.

  Therefore, it is necessary to easily and accurately generate a prediction signal in the spatial domain. In addition, a configuration capable of high-speed operation is required in the encoding device and the decoding device.

  By the way, encoding of image data has been widely used in many international standards such as JPEG, MPEG1, H.261, MPEG2 and H.263. Each of the latter standards further improves coding efficiency. That is, an effort has been made to further reduce the number of bits compared to the conventional standard to express the same image quality.

Encoding of image data for a moving image includes intra-frame encoding and predictive frame encoding. Here, intra-frame coding refers to intra-frame coding of one frame within a screen. In a typical hybrid coding system, such as the MPEG1 standard, successive frames can be classified into three different types:
(A) Intra frame (hereinafter referred to as I frame),
(B) Predicted frame (hereinafter, referred to as P frame), and (c) Bidirectional predicted frame (hereinafter, referred to as B frame).

  I-frames are encoded independently of other frames, ie, I-frames are compressed without using other frames. The P frame has been encoded through motion detection and compensation by using the previous frame to predict the contents of the encoded frame (which is a P frame). B-frames are encoded by using motion detection and compensation using information from the previous frame and information from subsequent frames to predict the contents of the B-frame. The previous and subsequent frames are either I frames or P frames. The I frame belongs to the intra code mode. The P frame and the B frame belong to the prediction code mode.

  Just as the encoding properties of I-frames, P-frames and B-frames are different, their compression methods are also different. I-frames require more bits than P-frames and B-frames because they do not use temporal prediction to reduce redundancy.

  Here, MPEG2 will be described as an example. Assume that the bit rate is 4 Mbit / s and the image is a 30 frame / s image. Generally, the ratio of the number of bits used for I, P and B frames is 6: 3: 1. Thus, an I frame uses about 420 Kbits / s and a B frame uses about 70 Kbits / s. This is because the B frame is sufficiently predicted from both directions.

  FIG. 14 is a block diagram illustrating a configuration of a conventional image prediction encoding device. Since the DCT transform is performed on a block basis, all modern image coding methods are based on dividing an image into smaller blocks. In the intra-frame coding, first, as shown in FIG. 14, block sampling processing 1001 is performed on an input digital image signal. Then, after DCT transform processing 1004 is performed on these blocks after block sampling processing 1001, quantization processing 1005 and run-length Huffman variable length coding (VLC) processing 1006 are performed. Is executed. On the other hand, in predictive frame coding, a motion compensation process 1003 is performed on an input digital image, and a DCT transform process 1004 is performed on a motion-compensated block (that is, a predicted block). You. Next, a quantization process 1005 and a run-length Hoffman VLC coding (entropy coding) process 1006 are executed.

  The block-based DCT transform process 1004 removes or reduces spatial redundancy in the block being processed, and the motion estimation and compensation processes 1002, 1003 provide temporary redundancy between adjacent frames. Is known from conventional image coding techniques. In addition, a run-length Hoffman VLC encoding or other entropy encoding process 1006, performed after the DCT transform process 1004 and the quantization process 1005, removes statistical redundancy between the quantized DCT transform coefficients. . However, the processing is performed only for blocks in the screen.

  Digital images inherently have large spatial redundancy. This redundancy exists not only in blocks within a frame of an image, but also between blocks across blocks. However, it is clear from the above that the actual method does not use a method of removing redundancy between blocks of the image.

  In current image coding techniques, the DCT transform 1004 or other transform is performed on a block basis due to hardware implementation and computational constraints.

  Spatial redundancy is reduced by the block-based transformation process, but only within one block. The redundancy between two adjacent blocks is not considered very well, but could be further reduced with intra-frame coding, which always consumes a large number of bits.

  In addition, the block-based DCT transform process removes or reduces spatial redundancy in the block being processed, and the motion estimation and compensation process reduces the temporal redundancy between two adjacent frames. Eliminating or reducing redundancy is known from current image coding techniques. A zigzag scan and run-length Huffman VLC encoding process or other entropy encoding process that is performed after the DCT transform and quantization process removes statistical redundancy in the quantized DCT transform coefficients. Note that it is limited to one block.

  Digital images inherently contain high spatial redundancy. This redundancy exists not only within blocks, but also across and between blocks of the image. Therefore, as is apparent from the above, the existing method does not use any method for removing redundancy between blocks of one image except for the prediction of DC coefficients of JPEG, MPEG1, and MPEG2.

  In MPEG1 and MPEG2, DC coefficient prediction is performed by subtracting the DC value of the previous coded block from the currently coded block. This is a simple prediction method that has no adaptability or mode switching when the prediction is not appropriate. Furthermore, it only contains DC coefficients.

  In the current state of the art, zig-zag scanning is used for all blocks before run-length encoding. No attempt has been made to make the scan adaptive based on the contents of the block.

  FIG. 22 is a block diagram illustrating a configuration of a conventional image prediction encoding device. In FIG. 22, the image prediction coding apparatus of the related art includes a block sampling unit 2001, a DCT transform unit 2003, a quantization unit 2004, a zigzag scan unit 2005, and an entropy coding unit 2006. In this specification, the term “unit” means a circuit device.

  In intra-frame coding (that is, intra-frame coding), after a block sampling process 2001 is performed on an input image signal, a DCT transform process 2003 is directly performed, and a quantization process is performed. 2004, a zigzag scan process 2005 and an entropy encoding process 2006 are sequentially executed. On the other hand, in inter-frame coding (ie, inter-frame coding, ie, predictive frame coding), after block sampling processing 2001, motion detection and compensation processing is performed in unit 2011, and then The prediction error is obtained by the adder 2002 by subtracting the detection value from the unit 2011 from the image data. Further, a DCT transform process 2003 is performed on the prediction error, and then a quantization process 2004, a zigzag scan process 2005, and an entropy coding process 2006 are performed in the same manner as the intra-frame coding.

  In the local decoder provided in the image predictive encoding device in FIG. 22, the inverse quantization process and the inverse DCT transform process are executed in units 2007 and 2008. In intra-frame coding, the motion-detected and compensated predictions are added by an adder 2009 to the prediction errors reconstructed by units 2007 and 2008, and the additions are added to the locally decoded image data , And the decoded image data is stored in the frame memory 2010 of the local decoder. Finally, the bit stream is output from the entropy coding unit 2010 and transmitted to the other image prediction decoding apparatus.

  FIG. 23 is a block diagram showing a configuration of a conventional image prediction decoding apparatus. The bit stream is decoded by a variable length decoder (VLD: Variable Length Decoding) unit (or entropy decoding unit) 2021, and then the decoded image data is subjected to inverse quantization and inverse DCT. This is executed in units 2023 and 2024. In inter-frame coding, the motion-detected and compensated predictions formed in unit 2027 are added to the reconstructed prediction error by adder 2025 to form locally decoded image data. The locally decoded image data is stored in the frame memory 1026 of the local decoder.

JP-A-4-306095.

  In current image coding techniques, the DCT or other transform process is performed on a block basis due to hardware implementation and computational constraints. Spatial redundancy will be reduced by block-based transformations. However, it is only within a block. Redundancies between adjacent blocks are not sufficiently considered. In particular, no special consideration is given to intra-frame coding that always consumes a large number of bits.

  A first object of the present invention is to provide an image prediction encoding apparatus and method, and an image prediction decoding apparatus and method capable of easily, quickly and accurately generating predicted image data in a spatial domain. It is in.

  Further, a second object of the present invention is to eliminate the redundancy in a block and to more efficiently encode image data as compared with a conventional image prediction encoding apparatus and image prediction decoding apparatus. It is an object of the present invention to provide an image prediction encoding device and method, and an image prediction decoding device and method, which can be encoded or decoded.

  Furthermore, a third object of the present invention is to solve the problem that important transform coefficients are concentrated in different areas of a block depending on the internal properties of image data, and to provide a correct scanning method for a block. It is an object of the present invention to provide an image prediction encoding apparatus and method, and an image prediction decoding apparatus and method, which can improve the efficiency of entropy encoding processing by determining.

  Still another object of the present invention is to provide a recording medium which records each step of the above-mentioned image predictive encoding method or image predictive decoding method.

The image prediction encoding method according to the present invention, sampling the image signal into a plurality of blocks,
Converting the image signal of the block into a two-dimensional sequence of DCT coefficients having DC coefficients and AC coefficients;
Predicting a DC coefficient of the current block (C) from a DC coefficient of an adjacent block adaptively selected from either the left block (B) or the upper block (A).

  Preferably, the image prediction encoding method further includes quantizing the DCT coefficient before predicting the DC coefficient.

  Further, in the above-described image prediction encoding method, preferably, the prediction of the DC coefficient of the current block (C) is independently repeated over all the blocks of the macroblock.

The image prediction encoding method according to the present invention, sampling the image signal into a plurality of blocks,
Converting the image signal of the block into a two-dimensional sequence of DCT coefficients having DC coefficients and AC coefficients;
Predicting DC and AC coefficients of the current block (C) from the DCT coefficients of adjacent blocks adaptively selected from either the left block (B) or the upper block (A). Features.

The image prediction encoding method according to the present invention, the image signal is sampled into a plurality of blocks,
Converting the image signal of the block into a two-dimensional sequence of DCT coefficients having DC coefficients and AC coefficients;
Predicting the DC coefficient of the current block (C) from the DC coefficient of an adjacent block adaptively selected from either the left block (B) or the upper block (A);
The AC coefficient of the current block (C) is
(A) when the DC coefficient of the current block is selected from the left block (B), the first column of the left block (B);
(B) when the DC coefficient of the current block is selected from the upper block (A), predicting from a set of any of the coefficients with the first row of the upper block (A). And

  In the image prediction encoding method, preferably, the DC coefficient of the current block (C) is obtained from the DC coefficient of the adjacent block selected from either the left block (B) or the upper block (A). Is predicted according to the least bit use rule.

  Further, the image prediction encoding method preferably further comprises supplying an indication bit indicating whether or not the AC coefficient of the current block is predicted from the adjacent block.

The image prediction encoding method according to the present invention, sampling the image signal into a plurality of blocks,
Converting the image signal of the block into a two-dimensional sequence of DCT coefficients having DC coefficients and AC coefficients;
Quantizing the DCT coefficients into a quantized DCT value;
Predicting the quantized DC coefficients of the current block from the DC coefficients of adjacent blocks adaptively selected from either the left block or the upper block,
The DC coefficient of a block selected for use in the prediction of the quantized DC coefficient of the current block is measured by a ratio of a quantization step size of the current block to a quantization step size of the selected block. It is characterized by being performed.

The image prediction encoding method according to the present invention, sampling the image signal into a plurality of blocks,
Converting the image signal of the block into a two-dimensional sequence of DCT coefficients having DC coefficients and AC coefficients;
Quantizing the DCT coefficients into a quantized DCT value;
Predicting the quantized DC coefficients and the quantized AC coefficients of the current block from the DCT coefficients of adjacent blocks adaptively selected from either the left block or the upper block,
The DCT coefficients of the block selected to be used for the prediction of the quantized DC coefficients of the current block (C) and the quantized AC coefficients are a quantization step size of the selected block. Is measured by a ratio of the quantization step size of the current block to the current block.

An image prediction encoding method according to the present invention includes: converting a block of a sampled image signal into a two-dimensional sequence of DCT coefficients;
Obtaining predicted DCT transform coefficients by predicting DCT coefficients of the current block from DCT coefficients of adjacent blocks adaptively selected from either the left block or the upper block;
Obtaining a two-dimensional sequence of a plurality of differential DCT coefficients by subtracting the predicted DCT transform coefficients from the DCT coefficients of the current block;
Scanning a two-dimensional sequence of the plurality of differential DCT coefficients and converting the two-dimensional sequence to a one-dimensional sequence of DCT coefficients;
The above scan is
(1) Zigzag scanning when the AC coefficient of the current block is not predicted in the prediction;
(2) vertical scanning when the AC coefficient of the current block is predicted and the DC prediction refers to the left block;
(3) The AC coefficient of the current block is predicted, and the DC prediction is performed by one of horizontal scanning when referring to an upper block.

  Preferably, the image prediction encoding method further includes performing a variable length encoding of the one-dimensional sequence of the DCT coefficients.

  Further, in the above-mentioned image predictive encoding method, preferably, the above-mentioned transformation is characterized in that a block of a sampled image signal is transformed into a plurality of 8 × 8 blocks of DCT coefficients.

Still further, in the image prediction encoding method, preferably, the scanning is performed by:
(1) When the AC coefficients of the current block (C) are not predicted in the prediction, a plurality of 8 × 8 blocks of DCT transform coefficients are zigzag scanned in the following order:
0, 1, 5, 6, 14, 15, 27, 28;
2, 4, 7, 13, 16, 26, 29, 42;
3, 8, 12, 17, 25, 30, 41, 43;
9, 11, 18, 24, 31, 40, 44, 53;
10, 19, 23, 32, 39, 45, 52, 54;
20, 22, 33, 38, 46, 51, 55, 60;
21, 34, 37, 47, 50, 56, 59, 61;
35, 36, 48, 49, 57, 58, 62, 63;
(2) In the prediction, the AC coefficient of the current block (C) is predicted, and when the DC prediction refers to the left block, vertical scanning is performed in the following order:
0, 4, 6, 20, 22, 36, 38, 52;
1, 5, 7, 21, 23, 37, 39, 53;
2, 8, 19, 24, 34, 40, 50, 54;
3, 9, 18, 25, 35, 41, 51, 55;
10, 17, 26, 30, 42, 46, 56, 60;
11, 16, 27, 31, 43, 47, 57, 61;
12, 15, 28, 32, 44, 48, 58, 62;
13, 14, 29, 33, 45, 49, 59, 63;
(3) In the prediction, the AC coefficient of the current block (C) is predicted, and when the DC prediction refers to the upper block, horizontal scanning is performed in the following order;
0, 1, 2, 3, 10, 11, 12, 13;
4, 5, 8, 9, 17, 16, 15, 14;
6, 7, 19, 18, 26, 27, 28, 29;
20, 21, 24, 25, 30, 31, 32, 33;
22, 23, 34, 35, 42, 43, 44, 45;
36, 37, 40, 41, 46, 47, 48, 49;
38, 39, 50, 51, 56, 57, 58, 59;
52, 53, 54, 55, 60, 61, 62, 63;
Is performed.

  Further, in the image predictive coding method, preferably, the DC coefficient of the current block (C) is determined from the DC coefficient of an adjacent block selected from the left block (B) or the upper block (A). The prediction is performed according to the least bit use rule.

  Further, the image prediction encoding method preferably further comprises supplying an indication bit indicating whether or not the AC coefficient of the current block is predicted from the adjacent block.

An image prediction encoding apparatus according to a first aspect of the present invention includes: a dividing unit configured to divide input encoded image data into image data of a plurality of small areas adjacent to each other;
When encoding the image data of the small area to be processed among the image data of a plurality of small areas adjacent to each other divided by the division means, the reproduced data adjacent to the image data of the small area to be processed is encoded. The image data of the reproduction small area is set as the image data of the intra-screen prediction small area of the processing target small area, the image data of the intra-screen prediction small area is set as the image data of the optimal prediction small area, First generating means for generating image data of a difference small area that is a difference between the image data and the image data of the optimal prediction small area;
Encoding means for encoding the image data of the small difference area generated by the generating means;
Decoding means for decoding the image data of the difference small area encoded by the encoding means,
A second generation unit that generates image data of the reproduced small region by adding the image data of the difference small region decoded by the decoding unit to the image data of the optimal predicted small region.

Further, the image prediction encoding apparatus according to the second invention is a division unit that divides the input encoded image data into image data of a plurality of small areas adjacent to each other,
When encoding a small area to be processed among a plurality of small areas adjacent to each other divided by the division means, image data of a reproduced small area reproduced adjacent to the image data of the small area to be processed. From among the above, only the significant image data indicated by the input significant signal indicating whether the encoded image data is significant is regarded as the image data of the intra-screen prediction small region of the small region to be processed, and The image data of the intra-screen prediction small area is used as the image data of the optimal prediction small area, and the image data of the difference small area that is the difference between the image data of the processing target small area and the image data of the optimal prediction small area is generated. First generating means;
Encoding means for encoding the image data of the small difference area generated by the first generation means;
Decoding means for decoding the image data of the difference small area encoded by the encoding means,
A second generation unit that generates image data of the reproduced small region by adding the image data of the difference small region decoded by the decoding unit to the image data of the optimal predicted small region.

Further, the image prediction decoding apparatus according to a third aspect of the present invention includes: an analysis unit that analyzes the input encoded image data sequence and outputs an image difference signal;
Decoding means for decoding the image data of the reproduction difference small area from the difference image signal output from the analysis means,
A line memory for storing image data for generating image data of a predetermined intra-screen prediction small area;
By executing a prediction signal generation process on the image data from the line memory, the reproduced image data adjacent to the image data of the reproduction difference small area is set as the image data of the intra-screen prediction small area, and the Generating means for outputting image data of the predicted small area as image data of the optimal predicted small area;
The image data of the reproduction difference small area from the decoding means and the image data of the optimal prediction small area from the generation means are added, and the image data for generating the in-screen prediction small area of the addition result is output. And an adder for storing the data in the line memory.

Still further, the image predictive decoding apparatus according to the fourth invention is characterized in that the analyzing means analyzes the input encoded image data sequence and outputs an image difference signal, a motion vector signal, and a control signal. ,
Decoding means for decoding the difference image signal output from the analysis means into image data of a reproduced difference small area;
Control means for outputting a switching signal for controlling the motion compensation means and the generation means to selectively operate, based on the control signal output from the analysis means,
A frame memory for storing predetermined reproduction image data;
A line memory for storing image data for generating image data of a predetermined intra-screen prediction small area;
By executing a motion compensation process on the input motion vector signal in response to the switching signal from the control means, image data of the temporal prediction small area is generated from the frame memory, and the optimal prediction small area is generated. Motion compensation means for outputting as image data of
By executing a prediction signal generation process on the image data from the line memory in response to the switching signal from the control means, the reproduced image data adjacent to the image data of the reproduction difference small area is displayed on the screen. Generating means for outputting image data of the intra prediction small area as image data of the intra prediction small area as image data of the intra prediction small area,
By adding the image data of the reproduction difference small area from the decoding means and the optimal prediction small area from the generation means, the reproduction image data of the addition result is output, and the reproduction image data is stored in the frame memory. And an adder for storing only image data for generating the image data of the intra-screen prediction small area in the line memory.

An image predictive decoding apparatus according to a fifth aspect of the present invention includes: an analyzing unit that analyzes an input encoded image data sequence and outputs a compressed shape signal and an image difference signal;
First decoding means for decoding the compressed shape signal output from the analysis means into a reproduced shape signal;
A second decoding unit that decodes the difference image signal output from the analysis unit into image data of a reproduced difference small area;
A line memory for storing image data for generating image data of a predetermined intra-screen prediction small area;
By performing prediction signal processing on the image data from the line memory, significant image data indicated by the reproduction shape signal is selected from the reproduced image data adjacent to the image data in the reproduction difference small area. Generating means for outputting only the image data of the intra-screen predicted small area as image data of the intra-screen predicted small area, and outputting the image data of the intra-screen predicted small area as image data of the optimal predicted small area;
By adding the image data of the reproduced difference small area from the second decoding means and the optimal predicted small area from the generating means, the image data of the addition result is output and the intra-screen predicted small area is added. And an adder for storing only the image data for generating the image data in the line memory.

Further, the image prediction decoding apparatus according to the sixth invention analyzes the input encoded image data sequence and outputs a compressed shape signal, an image difference signal, a motion vector signal, and a control signal. Analysis means to perform
First decoding means for decoding the compressed shape signal output from the analysis means into a reproduced shape signal;
A second decoding unit for decoding the difference image signal output from the analysis unit into a reproduction difference small area;
Control means for outputting a switching signal for controlling the motion compensation means and the generation means to selectively operate based on the control signal output from the analysis means;
A frame memory for storing predetermined reproduction image data;
A line memory for storing image data for generating image data of a predetermined intra-screen prediction small area;
By performing a motion compensation process on the reproduced image data from the frame memory based on the motion vector signal output from the analysis means in response to the switching signal output from the control means, the temporal prediction is performed. Motion compensation means for generating image data of the small area and outputting the image data as the image data of the optimal predicted small area;
By performing a prediction signal process on the image data from the line memory in response to the switching signal output from the control means, the reproduced image data adjacent to the image data of the reproduction difference small area is processed. Generating means for outputting only significant image data indicated by the reproduction shape signal as image data of the intra-screen predicted small area, and outputting the image data of the intra-screen predicted small area as image data of the optimal predicted small area,
By adding the image data of the reproduction difference small area from the second decoding means and the optimal prediction small area from the generation means, the reproduction image data of the addition result is output, and the reproduction image data is added. An adding means for storing in the frame memory only image data for generating the intra prediction small area in the line memory.

An image prediction encoding apparatus according to a seventh aspect of the present invention includes: a sampling unit configured to sample an input image signal into image data of a plurality of blocks each including a two-dimensional array of pixel values;
Conversion means for converting the image data of the block sampled by the sampling means to coefficient data of a predetermined conversion area,
A block memory for storing the coefficient data of the restored block;
A prediction unit that forms coefficient data of a plurality of prediction blocks with respect to the coefficient data of the block converted by the conversion unit based on the coefficient data of the previously reconstructed block stored in the block memory;
From the coefficient data of the plurality of prediction blocks formed by the prediction means, the coefficient data of the most efficient prediction block is determined, selected and output, and the indicator representing the selected prediction block is designated by an indicator bit format. Determining means for transmitting to the image prediction decoding device at
First addition means for subtracting the coefficient data of the prediction block selected by the determination means from the coefficient data of the current block at the present time, thereby outputting coefficient data of a prediction error as a result of the subtraction;
Quantizing means for quantizing the prediction error coefficient data output from the first adding means;
Encoding means for entropy-encoding the prediction error coefficient data from the quantization means, and transmitting the encoded prediction error coefficient data to the image prediction decoding device;
Inverse quantization means for inversely quantizing the coefficient data of the prediction error from the quantization means and outputting the coefficient data of the restored block;
By adding the coefficient data of the prediction block output from the determination means to the coefficient data of the prediction error output from the inverse quantization means, the coefficient data of the restored block is output, and the block data is output to the block memory. Second adding means for storing;
An inverse transform unit for inversely transforming the coefficient data of the block output from the second adding unit to generate image data of the restored block.

An image prediction encoding apparatus according to an eighth aspect of the present invention includes a sampling unit that samples an input image signal into image data of a plurality of blocks including pixel values of a two-dimensional array,
Conversion means for converting the image data of a plurality of blocks sampled by the sampling means into coefficient data of a predetermined conversion area,
Quantizing means for quantizing the coefficient data of the transform area from the transforming means,
A block memory for storing the coefficient data of the restored block;
A prediction unit that forms coefficient data of a plurality of prediction blocks with respect to the coefficient data of the block converted by the conversion unit based on the coefficient data of the previously reconstructed block stored in the block memory;
From the coefficient data of the plurality of prediction blocks formed by the prediction means, the coefficient data of the most efficient prediction block is determined, selected and output, and the indicator representing the selected prediction block is designated by an indicator bit format. Determining means for transmitting to the image prediction decoding device at
First addition means for subtracting the coefficient data of the prediction block selected by the determination means from the coefficient data of the current block at the present time, thereby outputting coefficient data of a prediction error as a result of the subtraction;
Coding means for entropy coding the coefficient data of the prediction error from the first adding means and transmitting the coded coefficient data of the prediction error to the image prediction decoding device;
By adding the coefficient data of the prediction error from the first adding means to the coefficient data of the prediction block output from the determining means, the quantized coefficient data of the current block is restored and output, Second adding means for storing in the block memory;
An inverse quantization means for inversely quantizing and outputting the coefficient data of the current block output from the second addition means;
An inverse transform unit for inversely transforming the coefficient data of the current block from the inverse quantization unit to generate image data of a restored block.

Further, the image prediction encoding apparatus according to the ninth aspect includes a sampling unit that samples the input image signal into image data of a plurality of blocks each including a pixel value of a two-dimensional array,
Compensation means for generating and outputting image data of a prediction error of the motion-compensated block by performing a motion compensation process on the image data of the input block;
First adding means for subtracting the prediction error image data of the block output from the compensation means from the image data of the block output from the sampling means, and outputting the image data of the subtraction result block;
Conversion means for converting the image data of the block output from the first addition means into coefficient data of a predetermined conversion area;
A block memory for storing the coefficient data of the restored block;
A prediction unit that forms coefficient data of a plurality of prediction blocks with respect to the coefficient data of the block converted by the conversion unit based on the coefficient data of the previously reconstructed block stored in the block memory;
From the coefficient data of the plurality of prediction blocks formed by the prediction means, the coefficient data of the most efficient prediction block is determined, selected and output, and the indicator representing the selected prediction block is designated by an indicator bit format. Determining means for transmitting to the image prediction decoding device at
A second adding unit that outputs coefficient data of a prediction error resulting from the subtraction by subtracting the coefficient data of the prediction block selected by the determining unit from the coefficient data of the current block at the present time;
Quantizing means for quantizing the coefficient data of the prediction error output from the second adding means;
Encoding means for entropy-encoding the prediction error coefficient data from the quantization means, and transmitting the encoded prediction error coefficient data to the image prediction decoding device;
Inverse quantization means for inversely quantizing the coefficient data of the prediction error from the quantization means and outputting the coefficient data of the restored block;
By adding the coefficient data of the prediction block output from the determination means to the coefficient data of the prediction error output from the inverse quantization means, the coefficient data of the restored block is output, and the block data is output to the block memory. Third adding means for storing;
An inverse transforming means for inversely transforming the coefficient data of the block output from the third adding means to generate image data of the restored block;
By adding the image data of the prediction error of the motion-compensated block output from the compensation means to the image data of the restored block from the inverse transform means, the image data of the restored block is added to the compensation means. And a fourth adding means for outputting to

Still further, an image prediction encoding apparatus according to a tenth aspect of the present invention includes a sampling unit that samples an input image signal into image data of a plurality of blocks including pixel values of a two-dimensional array,
Compensation means for generating and outputting image data of a prediction error of the motion-compensated block by performing a motion compensation process on the image data of the input block;
First adding means for subtracting the prediction error image data of the block output from the compensation means from the image data of the block output from the sampling means, and outputting the image data of the subtraction result block;
Conversion means for converting the image data of the block output from the first addition means into coefficient data of a predetermined conversion area;
Quantizing means for quantizing the coefficient data of the transform area from the transforming means,
A block memory for storing the coefficient data of the restored block;
A prediction unit that forms coefficient data of a plurality of prediction blocks with respect to the coefficient data of the block converted by the conversion unit based on the coefficient data of the previously reconstructed block stored in the block memory;
From the coefficient data of the plurality of prediction blocks formed by the prediction means, the coefficient data of the most efficient prediction block is determined, selected and output, and the indicator representing the selected prediction block is designated by an indicator bit format. Determining means for transmitting to the image prediction decoding device at
A second adding unit that outputs coefficient data of a prediction error resulting from the subtraction by subtracting the coefficient data of the prediction block selected by the determining unit from the coefficient data of the current block at the present time;
Encoding means for entropy encoding the coefficient data of the prediction error from the second adding means, and transmitting the encoded coefficient data of the prediction error to the image prediction decoding apparatus;
By adding the coefficient data of the prediction error from the second addition means to the coefficient data of the prediction block output from the determination means, the quantized current block coefficient data is restored and output, Third adding means for storing in the block memory,
Inverse quantization means for inversely quantizing and outputting the coefficient data of the current block output from the third addition means,
Inverse transforming means for inversely transforming the coefficient data of the current block from the inverse quantizing means to generate image data of a restored block,
By adding the image data of the prediction error of the motion-compensated block output from the compensation means to the image data of the restored block from the inverse transform means, the image data of the restored block is added to the compensation means. And a fourth adding means for outputting to

An image prediction decoding device according to an eleventh invention is an image prediction decoding device provided corresponding to the image prediction encoding device according to the seventh invention,
Extracting means for extracting an instruction bit from the received data received from the image prediction encoding device,
A block memory for storing the coefficient data of the restored block;
Based on the prediction block indicated by the indication bit extracted by the extraction means, using the coefficient data of the previously restored block stored in the block memory, the coefficient data of the current block included in the received data is contained. Another prediction means for generating and outputting coefficient data of a prediction block for
Decoding means for entropy decoding the received data and outputting decoded prediction error coefficient data;
Inverse quantization means for inversely quantizing and outputting the prediction error coefficient data output from the decoding means,
By adding the coefficient data of the prediction block output from the another prediction means to the coefficient data of the prediction error output from the inverse quantization means, the coefficient data of the current block at the present time is restored and output. Third adding means for storing the data in the block memory;
Another inverse transforming means for inversely transforming the coefficient data of the current block output from the third adding means and outputting the restored image data of the current block is provided.

An image prediction decoding device according to a twelfth invention is an image prediction decoding device provided corresponding to the image prediction encoding device according to the eighth invention,
Extracting means for extracting an instruction bit from the received data received from the image prediction encoding device,
A block memory for storing the coefficient data of the restored block;
Based on the prediction block indicated by the indication bit extracted by the extraction means, using the coefficient data of the previously restored block stored in the block memory, the coefficient data of the current block included in the received data is contained. Another prediction means for generating and outputting coefficient data of a prediction block for
Decoding means for entropy decoding the received data and outputting decoded prediction error coefficient data;
By adding the coefficient data of the prediction block output from the prediction means to the coefficient data of the prediction error output from the decoding means, the coefficient data of the current block at the present time is restored and output. Third adding means for storing in a memory;
Inverse quantization means for inversely quantizing and outputting the prediction error coefficient data output from the third addition means,
Another inverse transforming means for inversely transforming the coefficient data of the current block output from the inverse quantizing means and outputting the restored image data of the current block.

Furthermore, an image prediction decoding device according to a thirteenth invention is an image prediction decoding device provided corresponding to the image prediction encoding device according to the ninth invention,
Extracting means for extracting an instruction bit from the received data received from the image prediction encoding device,
A block memory for storing the coefficient data of the restored block;
Based on the prediction block indicated by the indication bit extracted by the extraction means, using the coefficient data of the previously restored block stored in the block memory, the coefficient data of the current block included in the received data is contained. Another prediction means for generating and outputting coefficient data of a prediction block for
Decoding means for entropy decoding the received data and outputting decoded prediction error coefficient data;
Inverse quantization means for inversely quantizing and outputting the prediction error coefficient data output from the decoding means,
By adding the coefficient data of the prediction block output from the another prediction means to the coefficient data of the prediction error output from the inverse quantization means, the coefficient data of the current block at the present time is restored and output. Third adding means for storing the data in the block memory;
Another inverse transforming means for inversely transforming the coefficient data of the current block output from the third adding means and outputting the restored image data of the current block;
Another compensating means for outputting motion-compensated prediction error data by performing motion compensation processing on the image data of the current block output from the another inverse transform means,
The motion compensation prediction error data output from the another compensating unit is subtracted from the current block image data output from the another inverse transforming unit, and the image data of the block resulting from the subtraction is output. A fifth adding means.

Still further, an image prediction decoding apparatus according to a fourteenth invention is an image prediction decoding apparatus provided corresponding to the image prediction encoding apparatus according to the tenth invention,
Extracting means for extracting an instruction bit from the received data received from the image prediction encoding device,
A block memory for storing the coefficient data of the restored block;
Based on the prediction block indicated by the indication bit extracted by the extraction means, using the coefficient data of the previously restored block stored in the block memory, the coefficient data of the current block included in the received data is contained. Another prediction means for generating and outputting coefficient data of a prediction block for
Decoding means for entropy decoding the received data and outputting decoded prediction error coefficient data;
By adding the coefficient data of the prediction block output from the prediction means to the coefficient data of the prediction error output from the decoding means, the coefficient data of the current block at the present time is restored and output. Third adding means for storing in a memory;
Inverse quantization means for inversely quantizing and outputting the prediction error coefficient data output from the third addition means,
Another inverse transform means for inversely transforming the coefficient data of the current block output from the inverse quantization means and outputting the restored image data of the current block;
Another compensating means for outputting motion-compensated prediction error data by performing motion compensation processing on the image data of the current block output from the another inverse transform means,
The motion compensation prediction error data output from the another compensating unit is subtracted from the current block image data output from the another inverse transforming unit, and the image data of the block resulting from the subtraction is output. A fifth adding means.

An image prediction encoding apparatus according to a fifteenth aspect, comprising: sampling means for sampling an input image signal into image data of a plurality of blocks each including a two-dimensional array of pixel values;
Conversion means for converting the image data of the block sampled by the sampling means to coefficient data of a predetermined conversion area,
A block memory for storing the coefficient data of the restored block;
A prediction unit that forms coefficient data of a plurality of prediction blocks with respect to the coefficient data of the block converted by the conversion unit based on the coefficient data of the previously reconstructed block stored in the block memory;
The coefficient data of the most efficient prediction block and the scanning method among the coefficient data of the plurality of prediction blocks formed by the prediction means are determined, selected and output, and an instruction indicating the selected prediction block and the scanning method is provided. Determining means for transmitting a child to the image prediction decoding device in the form of an indication bit;
First addition means for subtracting the coefficient data of the prediction block selected by the determination means from the coefficient data of the current block at the present time, thereby outputting coefficient data of a prediction error as a result of the subtraction;
Quantizing means for quantizing the prediction error coefficient data output from the first adding means;
A scanning unit that performs a scan process on the coefficient data of the prediction error from the quantization unit using the scan method determined by the determination unit, and outputs coefficient data of the prediction error after the scan process;
Encoding means for entropy encoding coefficient data of the prediction error after the scan processing output from the scanning means, and transmitting the encoded coefficient data of the prediction error to the image prediction decoding device,
Inverse quantization means for inversely quantizing the coefficient data of the prediction error from the quantization means and outputting the coefficient data of the restored block;
By adding the coefficient data of the prediction block output from the determination means to the coefficient data of the prediction error output from the inverse quantization means, the coefficient data of the restored block is output, and the block data is output to the block memory. Second adding means for storing;
An inverse transform unit for inversely transforming the coefficient data of the block output from the second adding unit to generate image data of the restored block.

An image prediction encoding apparatus according to a sixteenth aspect of the present invention includes: a sampling unit that samples an input image signal into image data of a plurality of blocks including pixel values of a two-dimensional array;
Conversion means for converting the image data of a plurality of blocks sampled by the sampling means into coefficient data of a predetermined conversion area,
Quantizing means for quantizing the coefficient data of the transform area from the transforming means,
A block memory for storing the coefficient data of the restored block;
A prediction unit that forms coefficient data of a plurality of prediction blocks with respect to the coefficient data of the block converted by the conversion unit based on the coefficient data of the previously reconstructed block stored in the block memory;
The coefficient data of the most efficient prediction block and the scanning method among the coefficient data of the plurality of prediction blocks formed by the prediction means are determined, selected and output, and an instruction indicating the selected prediction block and the scanning method is provided. Determining means for transmitting a child to the image prediction decoding device in the form of an indication bit;
First addition means for subtracting the coefficient data of the prediction block selected by the determination means from the coefficient data of the current block at the present time, thereby outputting coefficient data of a prediction error as a result of the subtraction;
Scanning means for executing scan processing on the coefficient data of the prediction error from the first adding means by the scanning method determined by the determining means, and outputting coefficient data of the prediction error after the scanning processing;
Encoding means for entropy encoding coefficient data of the prediction error after the scan processing output from the scanning means, and transmitting the encoded coefficient data of the prediction error to the image prediction decoding device,
By adding the coefficient data of the prediction error from the first adding means to the coefficient data of the prediction block output from the determining means, the quantized coefficient data of the current block is restored and output, Second adding means for storing in the block memory;
An inverse quantization means for inversely quantizing and outputting the coefficient data of the current block output from the second addition means;
An inverse transform unit for inversely transforming the coefficient data of the current block from the inverse quantization unit to generate image data of a restored block.
Further, the image predictive encoding apparatus according to a seventeenth aspect includes: a sampling unit configured to sample the input image signal into image data of a plurality of blocks each including a two-dimensional array of pixel values;
Compensation means for generating and outputting image data of a prediction error of the motion-compensated block by performing a motion compensation process on the image data of the input block;
First adding means for subtracting the prediction error image data of the block output from the compensation means from the image data of the block output from the sampling means, and outputting the image data of the subtraction result block;
Conversion means for converting the image data of the block output from the first addition means into coefficient data of a predetermined conversion area;
A block memory for storing the coefficient data of the restored block;
A prediction unit that forms coefficient data of a plurality of prediction blocks with respect to the coefficient data of the block converted by the conversion unit based on the coefficient data of the previously reconstructed block stored in the block memory;
The coefficient data of the most efficient prediction block and the scanning method among the coefficient data of the plurality of prediction blocks formed by the prediction means are determined, selected and output, and an instruction indicating the selected prediction block and the scanning method is provided. Determining means for transmitting a child to the image prediction decoding device in the form of an indication bit;
A second adding unit that outputs coefficient data of a prediction error resulting from the subtraction by subtracting the coefficient data of the prediction block selected by the determining unit from the coefficient data of the current block at the present time;
Quantizing means for quantizing the coefficient data of the prediction error output from the second adding means;
A scanning unit that performs a scan process on the coefficient data of the prediction error from the quantization unit using the scan method determined by the determination unit, and outputs coefficient data of the prediction error after the scan process;
Encoding means for entropy encoding coefficient data of the prediction error after the scan processing output from the scanning means, and transmitting the encoded coefficient data of the prediction error to the image prediction decoding device,
Inverse quantization means for inversely quantizing the coefficient data of the prediction error from the quantization means and outputting the coefficient data of the restored block;
By adding the coefficient data of the prediction block output from the determination means to the coefficient data of the prediction error output from the inverse quantization means, the coefficient data of the restored block is output, and the block data is output to the block memory. Third adding means for storing;
An inverse transforming means for inversely transforming the coefficient data of the block output from the third adding means to generate image data of the restored block;
By adding the image data of the prediction error of the motion-compensated block output from the compensation means to the image data of the restored block from the inverse transform means, the image data of the restored block is added to the compensation means. And a fourth adding means for outputting to

Still further, an image prediction encoding apparatus according to an eighteenth aspect of the present invention includes a sampling unit configured to sample an input image signal into image data of a plurality of blocks including pixel values of a two-dimensional array,
Compensation means for generating and outputting image data of a prediction error of the motion-compensated block by performing a motion compensation process on the image data of the input block;
First adding means for subtracting the prediction error image data of the block output from the compensation means from the image data of the block output from the sampling means, and outputting the image data of the subtraction result block;
Conversion means for converting the image data of the block output from the first addition means into coefficient data of a predetermined conversion area;
Quantizing means for quantizing the coefficient data of the transform area from the transforming means,
A block memory for storing the coefficient data of the restored block;
A prediction unit that forms coefficient data of a plurality of prediction blocks with respect to the coefficient data of the block converted by the conversion unit based on the coefficient data of the previously reconstructed block stored in the block memory;
The coefficient data of the most efficient prediction block and the scanning method among the coefficient data of the plurality of prediction blocks formed by the prediction means are determined, selected and output, and an instruction indicating the selected prediction block and the scanning method is provided. Determining means for transmitting a child to the image prediction decoding device in the form of an indication bit;
A second adding unit that outputs coefficient data of a prediction error resulting from the subtraction by subtracting the coefficient data of the prediction block selected by the determining unit from the coefficient data of the current block at the present time;
Scanning means for executing scan processing on the coefficient data of the prediction error from the second adding means by the scanning method determined by the determining means, and outputting coefficient data of the prediction error after the scanning processing;
Encoding means for entropy encoding coefficient data of the prediction error after the scan processing output from the scanning means, and transmitting the encoded coefficient data of the prediction error to the image prediction decoding device,
By adding the coefficient data of the prediction error from the second addition means to the coefficient data of the prediction block output from the determination means, the quantized current block coefficient data is restored and output, Third adding means for storing in the block memory,
Inverse quantization means for inversely quantizing and outputting the coefficient data of the current block output from the third addition means,
Inverse transforming means for inversely transforming the coefficient data of the current block from the inverse quantizing means to generate image data of a restored block,
By adding the image data of the prediction error of the motion-compensated block output from the compensation means to the image data of the restored block from the inverse transform means, the image data of the restored block is added to the compensation means. And a fourth adding means for outputting to

An image prediction decoding apparatus according to a nineteenth aspect is an image prediction decoding apparatus provided corresponding to the image prediction encoding apparatus according to the fifteenth aspect,
Extracting means for extracting an instruction bit from the received data received from the image prediction encoding device,
A block memory for storing the coefficient data of the restored block;
Based on the prediction block indicated by the indication bit extracted by the extraction means, using the coefficient data of the previously restored block stored in the block memory, the coefficient data of the current block included in the received data is contained. Another prediction means for generating and outputting coefficient data of a prediction block for
Decoding means for entropy decoding the received data and outputting decoded prediction error coefficient data;
An inverse scan process is performed on the coefficient data of the prediction error output from the decoding unit based on the scan method indicated by the instruction bit extracted by the extraction unit, and the prediction error of the prediction error after the inverse scan process is performed. Inverse scanning means for outputting coefficient data;
Inverse quantization means for inversely quantizing and outputting the coefficient data of the prediction error after inverse scan processing output from the inverse scan means,
By adding the coefficient data of the prediction block output from the another prediction means to the coefficient data of the prediction error output from the inverse quantization means, the coefficient data of the current block at the present time is restored and output. Third adding means for storing the data in the block memory;
Another inverse transforming means for inversely transforming the coefficient data of the current block output from the third adding means and outputting the restored image data of the current block is provided.

An image prediction decoding apparatus according to a twentieth aspect is an image prediction decoding apparatus provided corresponding to the image prediction encoding apparatus according to the sixteenth aspect,
Extracting means for extracting an instruction bit from the received data received from the image prediction encoding device,
A block memory for storing the coefficient data of the restored block;
Based on the prediction block indicated by the indication bit extracted by the extraction means, using the coefficient data of the previously restored block stored in the block memory, the coefficient data of the current block included in the received data is contained. Another prediction means for generating and outputting coefficient data of a prediction block for
Decoding means for entropy decoding the received data and outputting decoded prediction error coefficient data;
An inverse scan process is performed on the coefficient data of the prediction error output from the decoding unit based on the scan method indicated by the instruction bit extracted by the extraction unit, and the prediction error of the prediction error after the inverse scan process is performed. Inverse scanning means for outputting coefficient data;
By adding the coefficient data of the prediction block output from the prediction means to the coefficient data of the prediction error output from the inverse scanning means, the coefficient data of the current block at the present time is restored and output. Third adding means for storing in a memory;
Inverse quantization means for inversely quantizing and outputting the prediction error coefficient data output from the third addition means,
Another inverse transforming means for inversely transforming the coefficient data of the current block output from the inverse quantizing means and outputting the restored image data of the current block.

Furthermore, an image prediction decoding apparatus according to a twenty-first aspect is an image prediction decoding apparatus provided corresponding to the image prediction encoding apparatus according to the seventeenth aspect,
Extracting means for extracting an instruction bit from the received data received from the image prediction encoding device,
A block memory for storing the coefficient data of the restored block;
Based on the prediction block indicated by the indication bit extracted by the extraction means, using the coefficient data of the previously restored block stored in the block memory, the coefficient data of the current block included in the received data is contained. Another prediction means for generating and outputting coefficient data of a prediction block for
Decoding means for entropy decoding the received data and outputting decoded prediction error coefficient data;
An inverse scan process is performed on the coefficient data of the prediction error output from the decoding unit based on the scan method indicated by the instruction bit extracted by the extraction unit, and the prediction error of the prediction error after the inverse scan process is performed. Inverse scanning means for outputting coefficient data;
Inverse quantization means for inversely quantizing and outputting the coefficient data of the prediction error after inverse scan processing output from the inverse scan means,
By adding the coefficient data of the prediction block output from the another prediction means to the coefficient data of the prediction error output from the inverse quantization means, the coefficient data of the current block at the present time is restored and output. Third adding means for storing the data in the block memory;
Another inverse transforming means for inversely transforming the coefficient data of the current block output from the third adding means and outputting the restored image data of the current block;
Another compensating means for outputting motion-compensated prediction error data by performing motion compensation processing on the image data of the current block output from the another inverse transform means,
The motion compensation prediction error data output from the another compensating unit is subtracted from the current block image data output from the another inverse transforming unit, and the image data of the block resulting from the subtraction is output. A fifth adding means.
Still further, an image prediction decoding apparatus according to a twenty-second invention is an image prediction decoding apparatus provided corresponding to the image prediction encoding apparatus according to the eighteenth invention,
Extracting means for extracting an instruction bit from the received data received from the image prediction encoding device,
A block memory for storing the coefficient data of the restored block;
Based on the prediction block indicated by the indication bit extracted by the extraction means, using the coefficient data of the previously restored block stored in the block memory, the coefficient data of the current block included in the received data is contained. Another prediction means for generating and outputting coefficient data of a prediction block for
Decoding means for entropy decoding the received data and outputting decoded prediction error coefficient data;
An inverse scan process is performed on the coefficient data of the prediction error output from the decoding unit based on the scan method indicated by the instruction bit extracted by the extraction unit, and the prediction error of the prediction error after the inverse scan process is performed. Inverse scanning means for outputting coefficient data;
By adding the coefficient data of the prediction block output from the prediction means to the coefficient data of the prediction error output from the inverse scanning means, the coefficient data of the current block at the present time is restored and output. Third adding means for storing in a memory;
Inverse quantization means for inversely quantizing and outputting the prediction error coefficient data output from the third addition means,
Another inverse transform means for inversely transforming the coefficient data of the current block output from the inverse quantization means and outputting the restored image data of the current block;
Another compensating means for outputting motion-compensated prediction error data by performing motion compensation processing on the image data of the current block output from the another inverse transform means,
The motion compensation prediction error data output from the another compensating unit is subtracted from the current block image data output from the another inverse transforming unit, and the image data of the block resulting from the subtraction is output. A fifth adding means.

  The image prediction encoding method according to the twenty-third aspect includes a step in which each unit in the image prediction encoding apparatus is replaced with each step.

  Furthermore, an image prediction decoding method according to a twenty-fourth aspect includes a step in which each unit in the image prediction decoding apparatus is replaced with each step.

  A recording medium according to a twenty-fifth aspect of the present invention is a recording medium that stores a program including each step in the image prediction encoding method.

  Further, a recording medium according to a twenty-sixth aspect is a recording medium recording a program including each step in the image prediction decoding method.

As described above in detail, according to the image prediction encoding apparatus according to the present invention, a dividing unit that divides input encoded image data into image data of a plurality of small areas adjacent to each other,
When encoding the image data of the small area to be processed among the image data of a plurality of small areas adjacent to each other divided by the division means, the reproduced data adjacent to the image data of the small area to be processed is encoded. The image data of the reproduction small area is set as the image data of the intra-screen prediction small area of the processing target small area, the image data of the intra-screen prediction small area is set as the image data of the optimal prediction small area, First generating means for generating image data of a difference small area that is a difference between the image data and the image data of the optimal prediction small area;
Encoding means for encoding the image data of the small difference area generated by the generating means;
Decoding means for decoding the image data of the difference small area encoded by the encoding means,
A second generation unit that generates image data of the reproduced small region by adding the image data of the difference small region decoded by the decoding unit to the image data of the optimal predicted small region.
Therefore, a high-precision prediction signal can be easily generated with a small amount of computation compared to the conventional technology simply by using the reproduced pixel value adjacent to the image data of the small area to be processed as the pixel value of the intra-screen prediction signal. And the unique effect that the number of bits for intra-frame encoding can be reduced can be obtained.
Further, according to the image prediction encoding apparatus according to the present invention, a sampling unit that samples the input image signal into image data of a plurality of blocks each including a pixel value of a two-dimensional array,
Conversion means for converting the image data of the block sampled by the sampling means to coefficient data of a predetermined conversion area,
A block memory for storing the coefficient data of the restored block;
A prediction unit that forms coefficient data of a plurality of prediction blocks with respect to the coefficient data of the block converted by the conversion unit based on the coefficient data of the previously reconstructed block stored in the block memory;
From the coefficient data of the plurality of prediction blocks formed by the prediction means, the coefficient data of the most efficient prediction block is determined, selected and output, and the indicator representing the selected prediction block is designated by an indicator bit format. Determining means for transmitting to the image prediction decoding device at
First addition means for subtracting the coefficient data of the prediction block selected by the determination means from the coefficient data of the current block at the present time, thereby outputting coefficient data of a prediction error as a result of the subtraction;
Quantizing means for quantizing the prediction error coefficient data output from the first adding means;
Encoding means for entropy-encoding the prediction error coefficient data from the quantization means, and transmitting the encoded prediction error coefficient data to the image prediction decoding device;
Inverse quantization means for inversely quantizing the coefficient data of the prediction error from the quantization means and outputting the coefficient data of the restored block;
By adding the coefficient data of the prediction block output from the determination means to the coefficient data of the prediction error output from the inverse quantization means, the coefficient data of the restored block is output, and the block data is output to the block memory. Second adding means for storing;
An inverse transform unit for inversely transforming the coefficient data of the block output from the second adding unit to generate image data of the restored block.
Therefore, it is possible to provide a new image prediction encoding device and a new image prediction decoding device that increase the current encoding efficiency. In this device, no complicated means is required to increase the coding efficiency, and its circuit configuration can be formed very simply and easily.
Further, according to the image prediction encoding apparatus according to the present invention, a sampling unit that samples the input image signal into image data of a plurality of blocks each including a pixel value of a two-dimensional array,
Conversion means for converting the image data of the block sampled by the sampling means to coefficient data of a predetermined conversion area,
A block memory for storing the coefficient data of the restored block;
A prediction unit that forms coefficient data of a plurality of prediction blocks with respect to the coefficient data of the block converted by the conversion unit based on the coefficient data of the previously reconstructed block stored in the block memory;
The coefficient data of the most efficient prediction block and the scanning method among the coefficient data of the plurality of prediction blocks formed by the prediction means are determined, selected and output, and an instruction indicating the selected prediction block and the scanning method is provided. Determining means for transmitting a child to the image prediction decoding device in the form of an indication bit;
First addition means for subtracting the coefficient data of the prediction block selected by the determination means from the coefficient data of the current block at the present time, thereby outputting coefficient data of a prediction error as a result of the subtraction;
Quantizing means for quantizing the prediction error coefficient data output from the first adding means;
A scanning unit that performs a scan process on the coefficient data of the prediction error from the quantization unit using the scan method determined by the determination unit, and outputs coefficient data of the prediction error after the scan process;
Encoding means for entropy encoding coefficient data of the prediction error after the scan processing output from the scanning means, and transmitting the encoded coefficient data of the prediction error to the image prediction decoding device,
Inverse quantization means for inversely quantizing the coefficient data of the prediction error from the quantization means and outputting the coefficient data of the restored block;
By adding the coefficient data of the prediction block output from the determination means to the coefficient data of the prediction error output from the inverse quantization means, the coefficient data of the restored block is output, and the block data is output to the block memory. Second adding means for storing;
An inverse transform unit for inversely transforming the coefficient data of the block output from the second adding unit to generate image data of the restored block.
Therefore, it is very effective in reducing or eliminating redundancy in the transform domain beyond adjacent blocks, reducing the number of bits used, and thereby greatly improving the coding efficiency. be able to. This is also useful as a tool in new video compression algorithms.

  Hereinafter, preferred embodiments according to the present invention will be described with reference to the accompanying drawings.

<First Embodiment Group>
The first embodiment group includes the first to fourth embodiments.

<First embodiment>
FIG. 1 is a block diagram illustrating a configuration of an image prediction encoding device according to a first embodiment of the present invention.

  In FIG. 1, 101 is an input terminal, 102 is a first adder, 103 is an encoder, 106 is an output terminal, 107 is a decoder, 110 is a second adder, 111 is a line memory, and 112 is a prediction. It is a signal generator.

  Hereinafter, the configuration and operation of the image prediction encoding device will be described. Image data to be encoded is input to an input terminal 101. Here, the input image data is divided into a plurality of adjacent small areas.

  FIG. 2 shows an image of input image data when divided into 8 × 8 small areas, and FIG. 3 shows an image of input image data when divided into triangular small areas. Image data of a plurality of small areas is sequentially encoded. Image data of a small area to be processed is input to the adder 102 via the input terminal 101 and the line 113. On the other hand, the prediction signal generator 112 generates image data of the intra-screen predicted small area, and outputs the generated image data to the adder 102 via the line 121 as the image data of the optimal predicted small area.

  The adder 102 subtracts the corresponding pixel value of the optimal prediction small area from the prediction signal generator 112 from the pixel value of the input image data in the processing target small area, and obtains the image data of the difference small area resulting from the subtraction. Is generated and output to the encoder 103 to execute a compression encoding process. In the present embodiment, the encoder 103 includes a DCT transformer 104 and a quantizer (Q) 105, and the image data in the small difference area is converted into an image signal in the frequency domain by the DCT converter 104, and the DCT transform coefficient Get. Next, the DCT transform coefficients are quantized by the quantizer 105. The quantized image data of the small area is output to the output terminal 106 via a line 116 and further converted into a variable-length or fixed-length code, and then stored on a recording medium such as an optical disk or via a communication line. (Not shown).

  At the same time, the quantized image data of the small area is input to a decoder 107, where the decoder 107 includes an inverse quantizer 108 and an inverse DCT transformer 109. Is restored to the image data of the expanded difference small area. In the present embodiment, after the input small region image data is inversely quantized by the inverse quantizer 108, the inversely quantized image data is converted to an inverse discrete cosine transform (hereinafter, referred to as an inverse DCT transformer). .) 109 converts the image signal into a spatial domain image signal. The obtained image data of the expanded difference small area is output to the adder 110, and the adder 110 outputs the image data of the expanded difference small area from the prediction signal generator 112 via the lines 121 and 122. The image data of the reproduction small area is generated by adding the optimum prediction image signal to be reproduced, and the reproduction pixel value for generating the intra-screen prediction image signal is stored in the line memory 111 from the image data of the reproduction small area. I do. The prediction signal generator 112 generates image data of an intra-screen prediction small area as described below. That is, the prediction signal generator 112 generates the pixel value of the reproduced image data adjacent to the image data of the small region to be processed as the pixel value of the image data of the intra prediction small region.

In FIG. 2, assuming that a block 200 is a small area to be processed, the pixel values of adjacent reproduced image data are a ₀ , a ₁ , a ₂ ,..., A ₆ , a ₇ , b ₀ , b ₁ , and b. ₂ ,..., B ₆ , b ₇ . 3, when the triangle 301 and the objective small region to be processed, the pixel values of the adjacent reconstructed image data _{g 0, g 1, ...,} g 4, f 0, f 1, f 2, ..., f 7 , it is a f _8. Assuming that the triangle 300 in FIG. 3 is a small area to be processed, the pixel values of the adjacent reproduced image data are e ₀ , h ₀ , h ₁ ,..., H ₄ . These pixel values are stored in the line memory 111. The prediction signal generator 112 accesses the line memory 111 and reads out the pixel values of the adjacent image data as the pixel values of the image data of the intra prediction small area.

  FIGS. 4 and 5 are block diagrams showing the configuration of the first and second embodiments of the prediction signal generator used in the image prediction encoding apparatus of FIG. 1, respectively.

In FIG. 4, pixel values a ₀ , a ₁ , a ₂ ,..., A ₆ , and a ₇ horizontally adjacent to the small region to be processed are input from the line memory 111 to the prediction signal generator 112, The generator 401 in the signal generator 112 generates the image data 403 of the intra-screen prediction small area by repeatedly outputting the same pixel in the horizontal direction, for example, eight times. Here, the image data 403 of the intra-screen predicted small area is used when there is no pixel adjacent to the small area to be processed in the vertical direction.

In FIG. 5, pixel values b ₀ , b ₁ , b ₂ ,..., B ₆ , and b _{7 that} are vertically adjacent to the small region to be processed are input from the line memory 111 to the prediction signal generator 112 and predicted. The generator 402 in the signal generator 112 generates image data 404 of the intra prediction small area by repeatedly outputting pixels in the vertical direction, for example, eight times. Here, the image data 404 of the intra-screen predicted small area is used when there is no pixel horizontally adjacent to the small area to be processed. When there are adjacent pixel values in both the horizontal direction and the vertical direction, image data of an intra prediction small area is generated as in the third embodiment shown in FIG.

  FIG. 6 is a block diagram showing the configuration of a third embodiment of the prediction signal generator used in the image prediction encoding apparatus of FIG.

  6, image data 403 of an intra-screen prediction small area generated by a generator 401 (see FIG. 5) and image data 404 of an intra-screen prediction small area generated by a generator 402 are sent to an adder 500. The input, adder 500 averages the two input image data by dividing the sum of the two input image data by two. As described above, since the adjacent reproduced pixels are repeatedly output by the generators 401 and 402 and only the averaging operation is performed by the adder 500, the image data of the intra prediction small area can be generated at high speed. . Note that the image data of the intra prediction small area may be generated by linearly interpolating the pixel values of two adjacent image data.

  FIG. 7 is a block diagram showing the configuration of a fourth embodiment of the prediction signal generator used in the image prediction encoding device of FIG.

In FIG. 7, pixel values a ₀ , a ₁ , a ₂ ,..., A ₆ , and a ₇ of image data horizontally adjacent to the small region to be processed are input from the line memory 111 to the generator 401. , The generator 401 generates image data of the first intra prediction small area by repeatedly outputting pixels in the horizontal direction. On the other hand, pixel values b ₀ , b ₁ , b ₂ ,..., B ₆ , and b _{7 that} are vertically adjacent to the small region to be processed are input from the line memory 111 to the generator 402, and the generator 402 The image data of the second intra prediction small area is generated by repeatedly outputting pixels in the vertical direction. The image data of the first intra-screen predicted small area and the image data of the second intra-screen predicted small area are input to the adder 500, and these two image data are averaged to obtain a third intra-screen predicted small area. Generate image data for the area.

  On the other hand, the image data of the small area to be processed is input to error calculators 601, 602, and 603 via line 616. Here, the image data of the first predicted small area in the screen and the image data of the small area to be processed are input to an error calculator 601, and the error calculator 601 calculates the absolute value of the error between the two image data. Is calculated and output to the comparator 604. Further, the image data of the second predicted small area in the screen and the image data of the small area to be processed are input to the error calculator 602, and the error calculator 602 is the absolute value of the error between these two pieces of image data. The second absolute error is calculated and output to the comparator 604. Further, the image data of the third predicted small area in the screen and the image data of the small area to be processed are input to the error calculator 603, and the error calculator 603 calculates the absolute value of the error between these two image data. A certain third absolute error is calculated and output to the comparator 604.

  The comparator 604 compares the three input absolute errors with each other, determines the one with the smallest absolute error, and sets the switch 605 so as to output the image data of the intra prediction small area corresponding to the absolute error to the line 121. Control. At the same time, the comparator 604 outputs an identifier for identifying the image data of the first, second, and third intra prediction small areas via the line 615 to the device on the receiving side or the reproducing side. With this identifier, the image data of the intra prediction small area on the screen is uniquely determined on the receiving side or the reproducing side. By using the image data of the intra prediction small area having the smallest error as described above, it is possible to suppress a difference signal at the time of encoding and to reduce the number of generated bits.

<Second embodiment>
FIG. 8 is a block diagram showing the configuration of an image predictive coding apparatus according to a second embodiment of the present invention, in which the same components as those in FIG. 1 are denoted by the same reference numerals. The image predictive coding apparatus of FIG. 8 is different from the image predictive coding apparatus of FIG. 1 in that a motion detector 700, a motion compensator 701, an optimal mode selector 703, and a frame memory 702 are additionally provided. Features.

  Hereinafter, the configuration and operation of the image predictive encoding device in FIG. 8 will be described.

  As in the first embodiment, the input image data of the small area to be processed is input to the adder 102 via the input terminal 101, and the adder 102 converts the image data of the small area to be processed into After subtraction from the image data of the optimal prediction small area input via the line 121 from the optimal mode selector 703, the image data resulting from the subtraction is output to the encoder 103. The encoder 103 compression-encodes the input subtracted image data and outputs it via the output terminal 106. At the same time, the encoder 103 outputs the compressed and encoded small-region image data to the decoder 107 to perform decompression decoding. After that, the image data is output to the adder 110, and the decompressed and decoded image data is added to the image data of the optimal prediction small area.

  Next, as in the first embodiment, only the pixel values of the image data used for generating the image data of the intra prediction small area are stored in the line memory 111, and all the pixel values of the reproduced image are stored in the line memory 111. The data is stored in the frame memory 702.

  When the image data of the next image is input via the input terminal 101, the motion detector 700 receives the image data of the small area to be processed and the reproduced image data stored in the frame memory 702. , The motion detector 700 detects the motion of the image by a method such as block matching, and outputs a motion vector via a line 705. The output motion vector is sent to the motion compensator 701 at the same time as, for example, being variable-length coded and stored or transmitted (not shown). The motion compensator 701 generates image data of a small temporal prediction region from the reproduced image in the frame memory 702 based on the motion vector, and outputs the image data to the optimal mode selector 703. The motion detection processing and the motion compensation processing include forward prediction, backward prediction, and bidirectional prediction, and these methods are disclosed in, for example, US Pat. No. 5,193,004.

  On the other hand, as in the first embodiment, the prediction signal generator 112 generates image data of the intra-screen prediction small area and outputs the image data to the optimal mode selector 703, and simultaneously optimizes the image data of the processing target small area. Output to the mode selector 703. The optimal mode selector 703 determines, based on the image data of the intra prediction small area and the image data of the temporal prediction small area, the image data of the small area to be processed (for example, the sum of the absolute values of the differences for each pixel). ) Is selected, and the selected image data is output to the adder 102 as the image data of the optimal prediction small area. Further, an identifier indicating which predicted small area image data is selected is output to the receiving side or the reproducing side via the line 709 and transmitted.

  As described above, since it is not necessary to transmit a motion vector between frames by introducing intra prediction into the image data of the inter-frame motion compensation coding, the number of bits can be further reduced.

  In the first and second embodiments, significant pixels are present on the entire screen. There may be pixels that are not significant if they are not significant in the screen. For example, in an image captured by chroma key, pixels representing a subject are significant, and pixels representing an area such as blue as a background are insignificant pixels. By encoding and transmitting the texture and the shape of a significant object, it is possible to reproduce and display the object. When the prediction signal generator 112 generates image data of an intra-screen prediction small area for such an input image, insignificant pixel values cannot be used.

  9 to 11 show schematic diagrams of an input image having significant pixels and insignificant pixels. In the present embodiment, a shape signal is used to indicate whether a pixel is significant. The shape signal is compression-encoded by a predetermined method and transmitted to a receiving side or a reproducing side. As a method of encoding a shape, there is a method such as chain encoding. The compressed shape signal is also expanded and reproduced, and an intra prediction signal is generated using the reproduced shape signal as described below.

In FIG. 9, the shape curve 800 is a boundary line, the direction indicated by the arrow is inside the object, and the image data inside the object is made up of significant pixels. Among the reproduced pixels adjacent to the small area 802 to be processed, b ₄ , b ₅ , b ₆ , and b ₇ are significant pixels, and only these pixel values are repeated to display the screen of the small area 802 to be processed. The pixel value of the intra prediction small area is used.

In FIG. 10, the shape curve 804 is a boundary line, the direction indicated by the arrow is inside the object, and the image data inside the object is made up of significant pixels. Of the reproduced pixels adjacent to the small area 805 to be processed, a ₄ , a ₅ , a ₆ , and a ₇ are significant pixels. Is the pixel value of the intra-screen prediction small area.

Further, in FIG. 11, the curve 808 is the boundary line, the direction indicated by the arrow is inside the object, and the image data inside the object is composed of significant pixels. Among the reproduced pixels adjacent to the small region 810 to be processed, a _{a 5, a 6, a 7} , b 4, b 5, b 6, b 7 significant pixels, and only these pixel values Is repeated, and where two pixel values overlap, a value obtained by averaging those pixel values is used as the pixel value of the intra-screen prediction small area of the small area 810 to be processed.

In FIG. 11, for example, the value of the pixel z _{77 in} the small region 810 to be processed is an average value of a ₇ and b ₇ . Where there is no pixel value, the average value of two pixel values adjacent in the horizontal and vertical directions is calculated. For example, the value of a pixel z ₁₄ is the average value of a ₅ and b _4. In this manner, image data of a screen prediction small area of an image having an arbitrary shape is generated.

  In the above embodiment, a small area divided into a square shape has been described. However, the present invention is not limited to this, and the screen may be divided into triangular small areas as in FIG. Also in this case, the image processing is executed similarly.

As another embodiment, an average value may be obtained using only significant pixel values, and the average value may be used as the pixel value of the intra-screen prediction small area. Specifically, in FIG. 9, the average value of the pixels b ₄ , b ₅ , b ₆ , and b ₇ is calculated, and the calculated average value is used as the pixel value of the intra-screen prediction small area. In FIG. 10, the average value of the pixels a ₄ , a ₅ , a ₆ , and a ₇ is calculated, and the calculated average value is used as the pixel value of the intra prediction small area. In FIG. 11, the average value of the pixels a ₅ , a ₆ , a ₇ , b ₄ , b ₅ , b ₆ , and b ₇ is calculated and used as the pixel value of the intra prediction small area.

<Third embodiment>
FIG. 12 is a block diagram illustrating a configuration of an image prediction decoding device according to the third embodiment of the present invention.

  12, 901 is an input terminal, 902 is a data analyzer, 903 is a decoder, 906 is an adder, 907 is an output terminal, 908 is a controller, 909 is a motion compensator, 910 is a prediction signal generator, and 911 is A line memory 912 is a frame memory.

  Hereinafter, the configuration and operation of the image prediction decoding apparatus of FIG. 12 will be described. In FIG. 12, the compression-encoded image data is input to a data analyzer 902, which analyzes the input image data and decodes the image data of the compressed difference small area via a line 915. And outputs a control signal to the controller 908 via a line 926, and outputs the above-described motion vector (if any) to the motion compensator 909. The decoder 903 includes an inverse quantizer 904 and an inverse DCT transformer 905, expands the compressed image data of the small difference area, and restores the image data of the expanded small difference area.

  In the present embodiment, the compressed image data of the small difference area is inversely quantized by the inverse quantizer 904, and the image data of the frequency domain after the inverse quantization is inversely quantized by the inverse DCT transformer 905. Converted to image data. The image data of the expanded difference small area after the conversion is input to the adder 906, and the adder 906 converts the input image data of the expanded difference small area from the motion compensator 923 or the prediction signal generator 922 to the switch 913 and the line. 924 is added to the image data of the optimal predicted small area transmitted via the 924 to generate image data of the reproduced small area as a result of the addition. The adder 906 outputs the reproduced image data to the output terminal 907 via the line 917 and stores the image data in the frame memory 912 at the same time. Further, the pixel value of the image data used to generate the image of the intra-screen prediction small area is stored in the line memory 911.

  Image data of the optimal prediction small area is determined by the controller 908 based on a control signal from the data analyzer 902, and switching of the switch 913 is controlled. When the image data of the intra prediction small area is selected by the controller 908, the switch 913 connects the line 924 to the line 922, and in response to the control signal from the controller 908, the prediction signal generator 910 switches the line memory 911 to the line memory 911. An access is made, and an adjacent reproduced pixel value is output as a pixel value of the intra prediction small area. The details of the operation of the prediction signal generator 910 have been described in detail above with reference to FIGS. When the image data of the temporal prediction small area is selected by the controller 908, the switch 913 connects the line 924 to the line 923, and in response to a control signal from the controller 908, the motion compensator 909 causes the data analyzer 902 Performs a motion compensation process on the image data from the frame memory 912 based on the motion vector sent from the frame 912 via the line 925 to generate the image data of the temporal prediction small area, and the switch 913 and the line 924 Is output to the adder 906 via.

<Fourth embodiment>
FIG. 13 is a block diagram showing the configuration of an image prediction decoding apparatus according to a fourth embodiment of the present invention. In FIG. 13, the same components as those in FIG. The image prediction decoding apparatus in FIG. 13 is characterized in that a shape decoder 990 is additionally provided in addition to the basic configuration of the image prediction decoding apparatus in FIG. The basic operation of the image prediction decoding apparatus in FIG. 13 is the same as that in FIG. 12, and only different operations will be described in detail below.

  In the present embodiment, the compression-encoded image data includes compression-encoded shape data. The data analyzer 902 extracts the shape data and outputs it to the shape decoder 990. In response, the shape decoder 990 expands and reproduces the shape signal. The reproduced shape signal is input to the prediction signal generator 910 while being transmitted to the reception side or the reproduction side. The prediction signal generator 910 generates image data of the intra-screen prediction small area based on the reproduced shape signal, as described with reference to FIGS. 9 to 11. In this way, image data of an intra-screen predicted small area of an image having an arbitrary shape can be generated, and the image data can be decoded and reproduced on the receiving side or the reproducing side.

  A feature of the third and fourth embodiments is that a line memory 911 is provided. If there is no line memory 911, pixels for generating image data of the intra prediction small area must be accessed from the frame memory 912. In order to generate a prediction signal using pixels in adjacent small regions, it is necessary to write and read the frame memory at high speed. By providing a dedicated line memory or buffer, it is possible to generate image data of the intra prediction small area at high speed without using a high-speed frame memory.

  In the above embodiment, the average value of the plurality of pixel values may be a predetermined weighted average value.

  As described above, according to the first embodiment of the present invention, the reproduced pixel value adjacent to the image data of the small area to be processed is simply used as the pixel value of the intra-screen prediction signal, Thus, it is possible to easily generate a high-precision prediction signal with a small amount of calculation as compared with the above, and to obtain a unique effect that the number of bits of intra-frame coding can be reduced. Further, since the line memory 911 is provided to store reproduced pixel values used for generating the intra-screen prediction signal, the pixel value can be accessed at high speed, and the intra-screen prediction signal can be transmitted at high speed. Can be generated.

<Second embodiment group>
The second embodiment group includes the fifth to seventh embodiments.

  In view of the problems of the prior art, the present inventor has found that the image coding efficiency is not only between two images or between two blocks in one image, but also between two blocks in one image. Has been found to further improve the image coding efficiency by removing the redundancy of.

  The inventor has found that the DCT transform coefficients at the same position in adjacent blocks are often very similar. In particular, it has been found that the approximation is high when the textures of the original images for the two blocks are very similar or include the same image pattern, for example, straight lines, corners, etc. The same information means redundancy by information theory.

  This type of redundancy, which exists in the DCT transform domain beyond the block, can be eliminated or greatly reduced by adaptive intra prediction (intra-frame prediction) from previous blocks. Then, in the next VLC entropy encoding process, higher encoding efficiency can be achieved by entropy with a small prediction. As a result of this DCT transform domain prediction, the input of redundant data to the VLC entropy coding circuit can be greatly reduced. This can save a lot of bits. Therefore, the image quality of the encoded image data is clearly improved.

  The present embodiment according to the present invention provides a scheme for appropriately predicting DCT transform coefficients from other blocks. This scheme removes the redundancy that exists beyond adjacent blocks and reduces the entropy of the quantized DCT transform coefficients, thereby reducing the number of bits required to encode the DCT transform coefficients. be able to.

  The DCT transform coefficient of the current block to be processed (hereinafter referred to as the current block) can be predicted from the DCT transform coefficient at the same position in the previous adjacent block. Adjacent blocks have already been decoded during processing. That is, the first DC coefficient is predicted by the first DC coefficient in one of the previously decoded neighboring blocks. Also, the second coefficient AC1 is predicted from the second coefficient AC1 in the same decoded block. Thereafter, the same operation is performed. By using this method, several predicted blocks are separated from the currently coded DCT transform block by an upwardly leftward, diagonally leftward, upwardly diagonally rightward, and upwardly adjacent neighbor. Can be obtained from the decoded block. These predicted blocks are checked by performing the actual entropy coding. Then, after a prediction block having a smaller number of bits is selected, the block is entropy-encoded and transmitted to an image prediction decoding device on the reception side or the reproduction side together with additional indication bits. The image prediction decoding apparatus is informed from which adjacent block the current block is predicted.

  The method of the present embodiment according to the present invention can predict the DCT transform coefficient of the current block. The DCT transform coefficients generally have good correlation with the DCT transform coefficients of other adjacent blocks. The reason is that the DCT transform tends to give the same value or the same distribution of DCT transform coefficients to similar block images.

  In general, first, a DCT transform process based on a block is performed on input image data, which is an intra frame or a temporarily predicted frame. After the DCT transform coefficients of the current block have been obtained, the prediction processing of the DCT transform domain can be executed before and after quantization.

  As shown in FIG. 15, the DCT transform coefficients of the current block are already decoded blocks, and are adjacent blocks, that is, upper left block B1, upper block B2, upper right block B3, and left block. It can be predicted from B4. The predicted block is obtained by subtracting all of the DCT transform coefficients of the current block from all of the DCT transform coefficients of the previous adjacent block at the same position. In addition, it can be obtained by partially subtracting DCT transform coefficients instead of all DCT transform coefficients.

  The predicted DCT transform coefficients in different predicted blocks are quantized if the prediction is performed before quantization. Next, entropy coding processing is performed on the DCT transform coefficients. The entropy coding process is the same as that of the image predictive coding device, and it is checked which predicted block is used as the lower bit.

  A prediction block using the lower bits is selected, and the selected prediction block is entropy coded with an indication bit that informs the picture prediction decoding device of the prediction decision.

  In the image prediction decoding device, a block predicted using the instruction bits is decoded. That is, after inverse entropy decoding of the DCT transform coefficients predicted for one block, the DCT transform coefficients for that block are the reference DCT transform coefficients of adjacent blocks that were decoded before represented by the indicator bits. Is added to the decoded DCT transform coefficients. Finally, an inverse DCT transform is applied to the reconstructed DCT transform coefficients for each block, yielding decoded image data.

  The present embodiment according to the present invention is based on spatial redundancy that is usually removed by a transform such as a DCT transform, redundancy that is removed between frames by motion estimation and compensation, and quantized transform coefficients within a block. It is an object of the present invention to provide an image coding apparatus capable of reducing other types of redundancy existing in the DCT domain beyond adjacent blocks, in addition to the statistical redundancy removed by entropy coding.

  As can be seen from FIG. 14 showing a prior art image predictive coding apparatus, the image predictive coding apparatus generally used for conventional image coding (for example, in MPEG) includes a block sampling unit 1001 and a DCT transform. A unit 1004, a quantizer 1005 and an entropy encoder 1006 are provided.

  In intra-frame coding (intra-frame coding), first, block sampling processing is performed on an input image signal. Next, DCT conversion processing is directly performed. Subsequently, a quantization process and an entropy coding process are performed. On the other hand, in the inter-frame encoding (prediction frame encoding), after the block sampling processing, the processing of the current frame to be processed is performed by the motion detection unit 1002 and the motion compensation unit 1003 on the image data. Further, DCT conversion processing is performed. Further, a quantization process and an entropy coding process are performed.

  Here, in the entropy encoding unit 1006, the quantized value is entropy-encoded and code data is output. Entropy coding is a method that assigns short codewords to frequently occurring values and long codewords to values that rarely occur, thereby encoding the data so as to approach the average amount of information, entropy. This is a method that greatly reduces the cost. This is lossless coding. Various schemes have been proposed as entropy coding, but Huffman coding is used in the baseline system. The Huffman coding method differs between the quantized DC coefficient value and the AC coefficient value, that is, the DC coefficient indicates the average value of an 8 × 8 pixel block, but in a general image, the average value of an adjacent block is Often have similar values. Therefore, entropy coding is performed after calculating the difference from the previous block. In this case, the values concentrate around zero, so that entropy coding is effective. For the AC coefficient, for example, zigzag scanning is performed to convert two-dimensional data into one-dimensional data. Further, since many 0s occur especially in the AC coefficient including the high frequency component, the entropy coding is performed by using the value of the AC coefficient having a value other than 0 and the number of the preceding 0s (run length) as a set.

  Rate controller 1007 feeds back the bits used for previously encoded blocks, controls the processing of quantization unit 1005, and adjusts the code bit rate. Here, the rate controller 1007 assigns a different bit amount to each encoded object data, each frame and each encoded block based on the nature of the encoded unit and the available bits. Control the code bit rate. In addition, the inverse quantization process and the inverse DCT transform process are executed in units 1008 and 1009 as a part of the local decoder. Image data decoded by the local decoder is stored in the local decoded frame memory 1010 and used for motion detection processing. Reference numeral 1011 denotes a reference frame memory for storing a previous original frame for motion detection. Finally, the bit stream is output from the entropy coding unit 1006 and sent to the image prediction decoding device on the receiving side or the reproducing side.

  FIG. 15 is a schematic diagram of an image for explaining an adaptive DCT transform area for intra prediction.

  FIG. 15 shows that, in the DCT transform area, four 8 × 8 DCT transform blocks constitute a macroblock. Here, B0 indicates the current block having the DCT transform coefficient of 8 × 8 at the present time. B2 indicates an upper adjacent block that has already been decoded. B1 and B3 indicate two obliquely adjacent blocks already decoded. B4 indicates the immediately preceding block adjacent to the left side. It can be seen from FIG. 15 that a block having DCT transform coefficients can be predicted from a plurality of decoded adjacent blocks having 8 × 8 DCT transform coefficients.

  It should be noted that it is always different from which block the current block was predicted. Therefore, a decision based on the minimum bit usage rule is performed, and the decision is adaptively given to different blocks on the image prediction decoding device side. The decision is notified to the image prediction decoding apparatus by the indication bit. Here, the minimum bit usage rule is used to determine a prediction method among a plurality of different prediction methods, and after each prediction method is applied, a bit amount used to encode a block is counted. You. As a result, the method that yields the least amount of bits used is selected as the prediction method to use.

  Note that DCT transform domain prediction can be performed after and / or before quantization.

<Fifth embodiment>
FIG. 16 is a block diagram illustrating a configuration of an image prediction encoding device according to a fifth embodiment of the present invention. The image prediction encoding apparatus in FIG. 16 is characterized in that the DCT transform region prediction processing is executed after the quantization processing.

  In FIG. 16, first, block sampling is executed by the block sampling unit 1012 on the input image signal. Then, in the intra-frame encoding, the sampled block image data is input to the DCT transform unit 1014 through the adder 1013 without being processed by the adder 1013. On the other hand, in predictive frame coding, the adder 1013 subtracts the motion detection image data output from the motion detection and compensation unit 1025 from the sampled block image data, and converts the resulting image data into a DCT transform unit 1014. Output to Then, after the DCT transform processing is executed by the unit 1014, the quantization processing is executed by the unit 1015.

  DCT transform domain prediction processing is performed in unit 1017, and 1018 is a block memory for storing previously decoded blocks for prediction. The adder 1016 subtracts the decoded adjacent block output from the DCT transform domain prediction unit 1017 from the current DCT transform block output from the quantization unit 1015. The determination of the encoded adjacent block is performed in the DCT transform domain prediction unit 1017. Finally, an entropy VLC encoding process is performed on the predicted DCT transform block by unit 1020, and the encoded bits are written to a bitstream.

  The adder 1019 restores the current DCT transform block by adding an adjacent block before being used for prediction to the prediction block. Next, inverse quantization and inverse DCT are performed on the restored DCT transform block in units 1021 and 1022, respectively. The image data of the block locally decoded and output from the inverse DCT transform unit 1022 is input to the adder 1023. The adder 1023 obtains reconstructed image data by adding the image data of the previous frame to the image data of the restored block, and stores the reconstructed image data in the frame memory 1024. Motion detection and compensation processing is performed in unit 1025. A frame memory 1024 is used to store previous frames for motion detection and compensation processing.

<Sixth embodiment>
FIG. 17 is a block diagram illustrating a configuration of an image prediction encoding device according to a sixth embodiment of the present invention. The image prediction encoding apparatus in FIG. 17 is characterized in that DCT transform area prediction processing is executed before quantization processing. The unit 1026 performs block sampling processing on the input image signal. Next, the adder 1027 performs subtraction for predictive frame encoding, and the image data resulting from the subtraction is passed through the DCT transform unit 1028, the adder 1029, and the quantization unit 1030, and the entropy VLC encoding unit 1034 and the inverse quantum Output to the conversion unit 1033.

  The block memory 1032 stores image data of the previous block for the DCT transform area prediction processing of the unit 1031. The image data of the current DCT transform block output from the DCT transform unit 1028 is subtracted by the adder 1029 from the previous DCT transform block selected by the DCT transform area prediction unit 1031 according to the minimum bit use rule. The image data of the DCT transform block resulting from the subtraction is quantized by the quantization unit 1030 and then output to the inverse quantization unit 1033 and the entropy VLC encoding unit 1034. The inverse quantization unit 1033 restores the input quantized image data of the DCT transform block by inverse quantization and outputs the restored image data to the adder 1035. The adder 1035 adds the image data of the previous DCT transform block from the DCT transform area prediction unit 1031 to the restored image data of the DCT transform block, and stores the image data of the previous block as the addition result in the block memory 1032. And outputs it to the inverse DCT transform unit 1036.

  The inverse DCT transform unit 1036 performs an inverse DCT transform process on the image data of the block before being input from the adder 1035, and outputs the restored image data after the transform process to the adder 1037. The adder 1037 adds the image data of the frame before output from the motion detection and compensation unit 1025 to the restored image data output from the inverse DCT transform unit 1036, and stores the image data of the addition result in the frame memory 1038. And then output to the motion detection and compensation unit 1025.

<B1. General description of mode determination>
FIG. 18 is a block diagram showing a configuration of the DCT transform region prediction circuits 1017 and 1031 in FIGS. 16 and 17.

In FIG. 18, reference numeral 1040 denotes a block memory for storing image data of a previous adjacent block for prediction. The current block to be processed is input to the unit 1041, and the unit 1041 subtracts the input image data of the current block from the previous adjacent DCT transform block stored in the block memory 1040 to obtain the next 4 blocks. Image data of various types of predictive DCT transform blocks are obtained.
(A) No-Pred block indicated by 1042,
(B) Up-Pred block indicated by 1043,
(C) Left-Pred block indicated by 1044,
(D) Another-Pred block indicated by 1045.

  Here, the above four types of blocks are shown using two bits. That is, for example, “00” indicates a No-Pred block, “01” indicates an Up-Pred block, “10” indicates a Left-Pred, and “11” indicates an Other-Pred block.

  The No-Pred block is the current image data of the DCT transform block at the time of no prediction. The Up-Pred block indicates image data of a prediction block obtained when the block used for prediction is the DCT transform block B2 adjacent adjacent above. The Left-Pred block indicates image data of a prediction block obtained when the block used for prediction is the DCT transform block B4 adjacent on the left. The Other-Pred block indicates image data of the prediction block when the prediction is performed only on the DC coefficient. In the case of Other-Pred, there are two types of prediction methods. That is, Up-DC-Pred (1046) indicates the image data of the prediction block obtained when the prediction is performed only on the DC coefficient based on the DCT transform block B2 adjacent above. Left-DC-Pred (1047) indicates image data of a prediction block obtained when prediction is performed only on the DC coefficient based on the DCT transform block B4 adjacent on the left side. For these two cases, another bit is needed for the indication. For example, "0" is used to indicate Up-DC-Pred (1046), and "1" is used to indicate Left-DC-Pred (1047).

  Although the prediction based on the blocks B1 and B3 that are obliquely adjacent to each other is possible, the prediction result is not as good as that based on the prediction for the upper and left blocks, and is not used in the present embodiment.

  All predicted blocks are checked and checked by performing the actual entropy coding process by unit 1048. The bits used for different predicted blocks are compared in unit 1049. Finally, unit 1050 determines the predicted DCT transform block based on the least bit usage rule and outputs the predicted DCT transform block along with the indication bits. That is, the predicted DCT transform block having the minimum number of bits is selected.

<B2. Implementation of mode determination>
FIG. 19 is a schematic diagram of an image showing an example of a coding method of DC / AC prediction in the DCT transform domain prediction circuit of FIG.

  In FIG. 19, a subset of the previously defined DC / AC predicted image data is shown for actual use. The current block 1101 is the upper left 8 × 8 block of the current macroblock, and the current block 1102 is the upper right 8 × 8 block of the current macroblock. A and B are 8 × 8 blocks adjacent to the current block 1101. The highlighted top row and left column of the current block 1101 are predicted from the same locations of adjacent blocks A and B, respectively. That is, the top row of the current block 1101 is predicted from the top row of the block A above it, and the left column of the current block 1101 is predicted from the left column of the left block B. In a similar procedure, the current block 1102 is predicted from the block D above and the current block 1 to the left.

Let C (u, v) be the block to be coded, and let E _i (u, v) be the prediction error for mode i, each block of A (u, v) and / or B (u, v) Is obtained by subtracting the predicted value from In a practical implementation, only the following three most frequent modes are used, as described in section B1.

(A) Mode 0: DC prediction only

[Equation 1]
E ₀ (0,0) = C (0,0) − (A (0,0) + B (0,0)) / 2,
E ₀ (u, v) = C (u, v),
u ≠ 0; v ≠ 0; u = 0,..., 7; v = 0,.

(B) Mode 1: DC / AC prediction from upper block

[Equation 2]
E ₁ (0, v) = C (0, v) −A (0, v), v = 0,.
E ₁ (u, v) = C (u, v),
u = 1, ..., 7; v = 0, ..., 7

(C) Mode 2: DC / AC prediction from left block [Equation 3]
E ₂ (u, 0) = C (u, 0) −B (u, 0), u = 0,.
E ₂ (u, v) = C (u, v),
u = 0, ..., 7; v = 1, ..., 7.

The mode is selected by calculating the sum of the absolute values of the errors predicted for the four luminance signal blocks in the macroblock, SAD _modei , and selecting the mode having the minimum value.

[Equation 4]
SAD _modei
= Σ [E _i (0,0) + 32 · ΣE _i (u, 0) + 32 · ΣE _i (0, v)],
b u v
i = 0, ..., 2; b = 0, ..., 3; u, v = 1, ..., 7

  The mode determination can be performed both on a block basis and on a macroblock basis, depending on differences in applications targeting different coding bit rates. The modes are encoded using the variable length codes in Table 1 below.

  When DC / AC prediction is performed after quantization, the preceding horizontal neighboring block or vertical neighboring block usually uses different quantization steps, so in order to perform DC / AC prediction accurately, Several types of weighting factors are needed to scale the quantized DCT transform coefficients.

  Let QacA be the quantized DCT transform coefficient of block A (see FIG. 19) and QacB be the quantized DCT transform coefficient of block B (see FIG. 19). Assuming that QstepA is a quantization step used for quantization of block A, QstepB is a quantization step used for quantization of block A, and QstepC is a quantization step used for quantization of current block C. , And thus the scaling equation is:

[Equation 5]
Q'acA = (QacA × QstepA) / QstepC
[Equation 6]
Q′acB = (QacB × QstepB) / QstepC

  Here, Q'acA is a DCT transform coefficient from block A, and is used for prediction of the top row of current block C. Q′acB is a DCT transform coefficient from block B, and is used for prediction of the left column of current block C.

<Seventh embodiment>
FIG. 20 is a block diagram illustrating a configuration of an image prediction decoding device according to the seventh embodiment of the present invention.

  In FIG. 20, the bit stream from the image prediction coding apparatus is input to an entropy VLD decoding unit 1051 and is subjected to variable length decoding. The image data of the DCT transform block is restored by adding the decoded image data to the image data of the previous adjacent DCT transform block from the DCT transform region prediction unit 1053 by the adder 1052. Which block is the previous neighboring DCT transform block is signaled by indication bits taken from the bitstream and used in unit 1053 for prediction. Reference numeral 1054 denotes a block memory for storing adjacent DCT transform blocks used for prediction. The restored DCT transform block obtained from the adder 1052 is output to the inverse DCT transform unit 1055. The inverse DCT transform unit 1055 performs an inverse DCT transform process on the input DCT transform block, generates restored DCT transform coefficient image data, and outputs the image data to the adder 1056. The adder 1056 adds the restored image data from the inverse DCT transform unit 1055 to the image data of the previous frame from the motion detection and compensation unit 1057 to thereby obtain a motion-detected and compensated and decoded image. Generate and output data. The decoded image data is temporarily stored in a frame memory for storing image data of a previous frame for motion detection and compensation, and then output to the motion detection and compensation unit 1057. The motion detection and compensation unit 1057 performs a motion detection and compensation process on the input image data.

  Further, the decoded image data output from the adder 1056 is restored to the original image data by a reverse restoration process corresponding to the process of the block sampling units 1012 and 1026 in FIGS.

  Further, reference numeral 1059 denotes an inverse quantization unit. When the DCT transform region prediction processing is performed before the quantization processing as shown in FIG. 17, the inverse quantization unit 1059 is inserted at the position of 1059a in FIG. On the other hand, when the DCT transform area prediction processing is performed after the quantization processing as shown in FIG. 16, the inverse quantization unit 1059 is inserted at the position of 1059b in FIG.

  FIG. 21 is a flowchart showing a decoding method of DC / AC prediction in the image prediction decoding apparatus of FIG. That is, FIG. 21 illustrates details of decoding of a bitstream for acquiring a DC / AC prediction mode and reconstructing DCT transform coefficients from adjacent DC / AC prediction values.

  First, in step 1059, the instruction bit is decoded from the input bit stream. In step 1060, the flag of the instruction bit is checked. If the flag is “0”, the image data of the upper block and the left block is determined in step 1061. The DC value is calculated from the average value of. If “NO” in the step 1060, the process proceeds to a step 1062. If the instruction flag checked in the step 1062 is “10”, the image data of the left column of the left block is extracted in a step 1063, and the process proceeds to a step 1065. If “NO” in the step 1062, the process proceeds to a step 1064. If the display flag checked in the step 1064 is “11”, the image data of the uppermost line of the upper block is extracted in a step 1065, and the process proceeds to a step 1066. Finally, in step 1066, the DCT transform coefficients obtained or extracted in step 1061, 1063, or 1065 are added to the corresponding DCT transform coefficients of the current block.

  Further, hereinafter, a modified example of the present embodiment group will be described.

(A) The block sampling units 1012 and 1026 indicate that the pixels of the two-dimensional array in the group of four blocks are composed of odd-numbered pixels in odd-numbered rows in the first block and in the second block. Consisting of even-numbered pixels in odd-numbered rows, in the third block consisting of odd-field pixels in even-numbered rows, and in fourth block consisting of even-numbered pixels in even-numbered rows, Interleaving processing for alternately inserting pixels may be included.
(B) The prediction block is selected from blocks previously stored in the block memory and previously restored and located adjacent to the coded current block, and includes all transforms in the block. A coefficient may be selected.
(C) the prediction block is selected from blocks previously stored in the block memory and previously reconstructed and located adjacent to the current block being coded, and a predetermined subset It may be selected as the transform coefficient of the block.

(D) the prediction block is selected from blocks previously stored in the block memory and previously restored, which are positioned adjacent to the upper and left sides of the coded current block; Only the transform coefficients in the top row and the leftmost column of the block may be used, and the remaining transform coefficients may be set to zero.
(E) The prediction block is selected from blocks previously stored in the block memory and previously restored and located near the encoded current block, and the transform coefficients of each block are weighted differently. It may be weighted by a function.
(F) The prediction block is selected from blocks previously stored in the block memory and reconstructed and located in the vicinity of the coded current block. A conversion operation may be performed.

(G) The prediction block may be a weighted average of a plurality of blocks stored in the block memory and previously restored, the blocks being located in the vicinity of the encoded current block.
(H) Based on the decoded image data, when forming a two-dimensional array of pixels from a plurality of groups of four interleaved blocks and restoring the original image data, the odd-numbered rows All odd-numbered pixels are obtained from the first block, even-numbered pixels in odd-numbered rows are obtained from the second block, and odd-numbered pixels in even-numbered rows are obtained from the third block. An inverse interleaving process may be performed on the decoded image data so that the even-numbered pixels in the first row are obtained from the fourth block.

  As described above, according to the present embodiment group according to the present invention, it is very effective to remove or reduce the redundancy of the DCT transform area between adjacent blocks, and as a result, the number of bits used can be reduced. Finally, the coding efficiency can be greatly improved. Referring to FIG. 18 as an example of a detailed image prediction encoding device, the prediction process is preferably performed only by using the upper or left adjacent block.

  For sequences containing QCIF, 6.4% of bits can be saved for higher bit rate coding and 20% of bits can be saved for lower bit rate coding. Also, about 10% of bits can be saved with respect to other QCIF sequences such as test sequences such as Akiyo, Mother, and Daughter. In addition, more bit savings are possible for CIF and CCIR sequences.

  As described above, according to the second embodiment group of the present invention, it is possible to provide a new image prediction coding device and a new image prediction decoding device that increase the current coding efficiency. In this device, no complicated means is required to increase the coding efficiency, and the circuit configuration can be formed very simply and easily.

<Third embodiment group>
The third embodiment group includes the eighth embodiment.

  In view of the problems of the prior art, the present inventor has found that the image coding efficiency reduces the redundancy between blocks in an image as well as between two images or within a block in one image. In addition, the present inventor has conceived to further improve the redundancy by making the block scan pattern appropriate.

  It has been found that the DCT transform coefficients in adjacent blocks at the same location are often very similar. This is true if the characteristics of the original images for the two blocks are very similar, or if the horizontal or vertical lines, diagonals and other image patterns contain the same. From an information theory perspective, the same information means redundancy.

  Redundancy that exists in the DCT transform domain beyond the block can be removed or reduced by the adaptive prediction of the previous block. This results in that VLC entropy coding can achieve higher coding efficiency for less entropy of the prediction error signal.

  At the same time, it is well known that horizontal and vertical structures result in a significant concentration of DCT transform coefficients in the leftmost column and topmost transform block. Therefore, the embodiment according to the present invention can solve the above-mentioned problems in coefficient scanning by adapting the scan based on the prediction mode.

  Embodiments according to the present invention provide a method for adaptively predicting DCT transform coefficients of a current block from other blocks, thereby removing redundancy between adjacent blocks. The prediction error information is further reduced by adapting the scanning method to a prediction mode that makes the entropy of the quantized DCT transform coefficients smaller. As a result, the number of bits for encoding DCT transform coefficients can be reduced.

  To solve this problem, a method for performing the prediction mode determination is obtained based on the actual bit rate generated by each prediction and scanning method.

  Embodiments according to the present invention provide a method for predicting DCT transform coefficients of a current block. Since the DCT transform tends to give the same value, or the same distribution of DCT transform coefficients, to the image data of the same block, the current block usually maintains good correlation with the DCT transform coefficients in other adjacent blocks. I have.

  The input image data is either an intra-frame or a temporarily predicted frame. First, a DCT transform process based on a normal block is performed on the input image data. Be executed. After the DCT transform coefficients of the current block are obtained, the prediction of the DCT transform domain can be performed before or after quantization.

  The DCT transform coefficient in the current block can be predicted from a previous adjacent block located diagonally (obliquely) on the upper left side. They have already been decoded at that time, as shown in FIG. The predicted block generates a predicted error signal by subtracting one or more DCT coefficients of a previous adjacent block from DCT coefficients of the same position in the current block.

  The prediction error signals from the different prediction modes are quantized if the prediction is made before the quantization process. The quantized prediction error signal is scanned against a sequence of image data before entropy coding is performed. The block predicted based on the minimum bit usage rule, that is, the predicted block having the minimum bit, is selected. The encoded data of this block is sent to the image prediction decoding device together with the prediction mode to be used.

  The image prediction decoding device decodes the predicted block using the used prediction mode and the encoded data of the block. After inverse entropy decoding on the encoded data for the block, the quantized prediction error is inversely scanned according to the scan mode used. If the quantization process is performed after the prediction process, the block will be dequantized. The reconstructed block may be obtained by adding the DCT transform coefficients in a previously decoded neighboring block, indicated by the prediction mode, to the current DCT transform coefficients. On the other hand, if the quantization process is performed before the prediction process, the reconstructed coefficients are inversely quantized. Finally, an inverse DCT transform is applied to the reconstructed DCT transform coefficients for each block to obtain a decoded image.

  An embodiment according to the present invention provides an image prediction encoding apparatus and an image prediction decoding apparatus that reduce redundancy existing in a DCT transform domain beyond an adjacent block.

<Eighth embodiment>
FIG. 24 is a block diagram illustrating a configuration of an image prediction encoding device according to the eighth embodiment of the present invention. The image prediction encoding apparatus of FIG. 24 is different from the image prediction encoding apparatus of the prior art of FIG.
(A) adder 2035,
(B) H / V / Z scan unit 2036,
(C) adder 2038,
(D) a block memory 2039; and (e) a DCT transform domain prediction unit 2040 having quantization scaling.

  In the intra-frame encoding (intra-frame encoding), after a block sampling process is performed on the input image signal by the unit 2031, the DCT transform process is directly performed by the unit 2033. Next, in the unit 2034, quantization processing is performed on the DCT transform coefficients output from the DCT transform unit 2033. On the other hand, in the inter-frame coding or the inter-frame coding (predictive frame coding), after the block sampling processing of the unit 2031, the adder 2032 uses the motion detection and compensation unit 2045 from the image data after the block sampling processing. By subtracting the output image data, prediction error data is obtained. Next, the prediction error data is output to the adder 2035 via the DCT transform unit 2033 that performs the DCT transform process and the quantization unit 2034 that performs the quantize process. The DCT transform coefficients are predicted by the DCT transform domain processing of the unit 2040, and the predicted DCT transform coefficients are input to the adder 2035. The adder 2035 subtracts the DCT transform coefficient predicted from the DCT transform area prediction unit 2040 from the DCT transform coefficient from the quantization unit 2034, and calculates the DCT transform coefficient of the prediction error of the subtraction result as H / V / Output to the Z scan unit 2036 and the adder 2038. The H / V / Z scan unit 2036 adaptively performs a horizontal scan, a vertical scan, or a zigzag scan on the input DCT transform coefficients depending on the selected prediction mode, and performs a scan process. The DCT transform coefficients are output to an entropy VLC encoding unit 2037. Next, the entropy VLC encoding unit 2037 performs an entropy VLC encoding process on the input DCT transform coefficients, and transmits the encoded bit stream to the image prediction decoding device on the reception side or the reproduction side.

  The adder 2038 adds the quantized DCT transform coefficient output from the adder 2035 and the predicted DCT transform coefficient from the DCT transform area prediction unit 2040 to obtain the restored quantized DCT transform coefficient. Get data. The quantized DCT transform coefficient data is output to the block memory 2039 and the inverse quantization unit 2041.

  In the local decoder provided in the image prediction encoding apparatus, the restored DCT transform coefficient data from the adder 2038 is temporarily stored in a block memory 2039 for storing data of one block for performing the next prediction. After that, it is output to the DCT transform domain prediction unit 2040. The inverse quantization unit 2041 inversely quantizes the input quantized DCT transform coefficient and outputs the result to the inverse DCT transform unit 2042, and then the inverse DCT transform unit 2042 converts the input restored DCT transform coefficient into the inverse DCT By executing the conversion process, the image data of the current block is restored and output to the adder 2043.

  In inter-frame coding, an adder 2043 is used to generate image data that has been motion-detected and compensated by the motion-detection and compensation unit 2045 and to recover the image data from the inverse DCT transform unit 2042 in order to generate locally decoded image data. The decoded image data is added to obtain locally decoded image data, which is stored in the frame memory 2044 of the local decoder. The configuration and processing of the adder 2043, the frame memory 2044, and the motion detection and compensation unit 2045 are the same as those of the units 2009, 2010, and 2011 of the related art in FIG.

  Finally, the bit stream is output from the entropy coding unit 2037 and sent to the image predictive coding device.

FIG. 25 is a block diagram illustrating a configuration of an image prediction decoding device according to the eighth embodiment of the present invention. The image prediction decoding device of FIG. 25 is different from the image prediction decoding device of the prior art of FIG.
(A) H / V / Z scan unit 2052,
(B) adder 2053,
(C) DCT transform region prediction unit 2055, and (d) block memory 2054,
It is characterized by having.

  In FIG. 25, the bit stream from the image prediction encoding device is decoded in the variable length decoder unit 2051. The decoded data is input to the H / V / Z reverse scan unit 2052 and is scanned horizontally in the reverse direction, vertically in the reverse direction, or zigzag in the reverse direction, depending on the scan mode. The data after the scan processing is input to an adder 2053, and the adder 2053 adds the data after the inverse scan processing and the prediction error data from the DCT transform prediction unit 2055 to obtain a decoded DCT transform coefficient. The data is obtained and output to the inverse quantization unit 2056 and stored in the block memory 2054. Next, the inverse quantization unit 2056 inversely quantizes the input coded DCT transform coefficient data to obtain inversely quantized DCT transform coefficient data, and outputs it to the inverse DCT transform unit 2057. The inverse DCT transform unit 2057 performs an inverse DCT transform process on the input DCT transform coefficient data, restores the original image data, and outputs it to the adder 2058. In the inter-frame encoding, the adder 2058 adds the image data from the inverse DCT transform unit 2057 to the prediction error data from the motion estimation and compensation unit 2060 to obtain the locally decoded image data. Output to an external device and stored in the frame memory 2059.

  Further, the decoded image data output from the adder 2058 is restored to the original image data by a reverse restoration process corresponding to the process of the block sampling unit 2031 in FIG.

  In the above embodiment, the quantization process is performed before the prediction process. In a modified example, a quantization process may be performed after the prediction process. In this case, in the local decoder and the image prediction decoding device, an inverse quantization process is performed before the prediction value is added. All other details are the same as in the above embodiment.

  FIG. 26 is a schematic diagram of an image showing a structure of a macroblock and a block of a frame obtained from block division and showing a block prediction method in the eighth embodiment. The enlarged view of FIG. 26 shows how the prediction data for the current block is encoded. Here, the block C (u, v) is obtained from the block A (u, v) adjacent on the upper side and the block B (u, v) adjacent on the left. Next, this embodiment will be described in more detail in the present invention.

<C1. Coefficient number used for forecasting>
The number of coefficients used for prediction depends on the sequence of image data. The flag AC_Coeff is used to adaptively select the optimal number of coefficients used for each image. The flags are shown in Table 2 below and are sent from the image prediction encoding device to the image prediction decoding device as part of the side information. Table 2 shows the fixed length code and FLC for the flag AC_Coeff. Here, FLC (Fixed Length Coding) is reversible coding that assigns a fixed length codeword to represent all possible events.

  Here, ACn is A (0, n) or B (n, 0), depending on the mode used.

  In the special case of this embodiment, all AC coefficients in the top row and leftmost column are used for prediction. In this case, when both the image predictive encoding device and the image predictive decoding device agree with this default value, no flag is required.

<C2. Scaling of quantization step>
When neighboring blocks are quantized using different quantization step sizes from the current block, the prediction of AC coefficients is not very efficient. Therefore, the prediction method is modified so that the prediction data is scaled by the ratio of the quantization step size of the current current block and the ratio of the quantization step of the block of prediction data. This definition is defined in the next section C3. Is given using the equation at.

<C3. Prediction mode>
The plurality of modes to be set are as follows.

(A) Mode 0: DC prediction from the block above the processing block (abbreviated as “upper DC mode”)

[Equation 7]
E ₀ (0,0) = C (0,0) −A (0,0),
E ₀ (u, v) = C (u, v)

(B) Mode 1: DC prediction from the block on the left side of the processing block (abbreviated as “left DC mode”)

[Equation 8]
E ₁ (0,0) = C (0,0) −B (0,0),
E ₁ (u, v) = C (u, v)

(C) Mode 2: DC / AC prediction from the upper block from the processing block (abbreviated as “upper DC / AC mode”)

[Equation 9]
E ₂ (0,0) = C (0,0) −A (0,0),
E ₂ (0, v) = C (0, v) −A (0, v) · Q _A / Q _C ,
v = 1, 2,..., AC_Coeff,
E ₂ (u, v) = C (u, v)

(D) Mode 3: DC / AC prediction from the block on the left side of the processing block (abbreviated as “left DC / AC mode”)

[Equation 10]
E ₃ (0,0) = C (0,0) -B (0,0),
E ₃ (u, 0) = C (u, 0) −B (u, 0) · Q _B / Q _C
u = 1, 2,..., AC_Coeff,
E ₃ (u, v) = C (u, v)

<C4. Adaptive Horizontal / Vertical / Zigzag Scan>
Given the four prediction modes as described above, the efficiency of intra-frame coding can be further improved by employing coefficient scanning.

  FIGS. 27, 28, and 29 are schematic diagrams of images for explaining the order of horizontal scan, vertical scan, and horizontal scan used for coefficient scanning in the eighth embodiment. Here, these scans are collectively referred to as H / V / Z scans.

<C5. Determination of explicit mode>
In the determination of the explicit mode, the determination of the prediction mode is performed in the image predictive coding apparatus, and the determination information is obtained by using some coded bit information in the bit stream. To the image prediction decoding device.

  FIG. 30 is a flowchart showing a mode determination process used in the eighth embodiment.

  In FIG. 30, the DCT transform coefficient data of the current block is input to a unit 2062, and the unit 2062 subtracts the input DCT transform coefficient data of the current block from the DCT transform coefficient data of the adjacent block from the block memory 2061. Performs a DCT transform prediction process. In the unit 2062, the sections C3. In the four modes described in the above, the DCT transform prediction processing is executed. Next, in the H / V / Z scan unit 2063, a coefficient scan process is performed. Here, as shown in FIG. The corresponding scan processing described in the above is executed. Further, the DCT transform coefficient data after the scan processing is sent to the entropy coding unit 2064, where the variable length coding processing is performed. Then, in unit 2065, all bits generated in the different modes are compared, and in unit 2066 a block of DCT transform coefficients in the prediction mode that produces the least number of bits is selected. These DCT transform coefficient data bits are sent from the unit 2066 as a bit stream to the image prediction decoding device together with the prediction mode value. Note that the prediction mode is encoded using the fixed length codes shown in Table 3 below.

<C6. Determination of Implicit Mode>
In the second embodiment of the mode determination, the image prediction encoding device and the image prediction decoding device share the same prediction mode determination function. Both the image prediction encoding device and the image prediction decoding device determine the directionality regarding the prediction mode determination based on the DC coefficient values of the decoded blocks adjacent to the current block. That is, in the determination of the implicit mode, the determination of the implicit mode is performed in the image prediction encoding device and the image prediction decoding device using some rules. Then, the additional information data indicating the mode determination is not sent from the image prediction encoding device to the image prediction decoding device.

  FIG. 31 is a schematic diagram of an image showing the relationship between blocks in the implicit mode determination according to the eighth embodiment. That is, FIG. 31 shows the positional relationship between each block and the current block to be predicted.

  In FIG. 31, a block C is a current block to be processed which is currently being predicted. Block A is a block above the current block C under prediction. Block C is a block located on the left side of current block C. The block C 'is a block between the block A and the block B which are diagonally opposite to the current block C.

  First, the direction of DC is determined. Using a separate determination method, it is determined whether the AC coefficient is also being predicted. To do this, the sum of the differences between the absolute values of the prediction coefficients is compared to the absolute value of the non-prediction coefficients to determine which is smaller. One bit is used for this instruction to the picture prediction decoding apparatus. The following equations are used to determine the direction of DC prediction and whether the AC coefficients are predicted. Table 3 summarizes the four possible conclusions.

(A1) If [Equation 11]
(B (0,0) -C '(0,0) <C' (0,0) -A (0,0))
When,
[Equation 12]
E (0,0) = C (0,0) -A (0,0)
And
(A1) If

[Equation 13]
7 7
(ΣC (0, v) ≧ ΣC (0, v) −A (0, v))
v = 1 v = 1

When,

[Equation 14]
E (0, v)
= C (0, v) -A (0, v) · Q _A / Q _C , v = 1, ..., 7,

(A2) If Equation 13 is not satisfied,
[Equation 15]
E (0, v) = C (0, v)
It is.

(A2) If Equation 11 is not satisfied,
[Equation 16]
E (0,0) = C (0,0) -B (0,0)
And
(B1) If

[Equation 17]
7 7
(ΣC (u, 0) ≧ ΣC (u, 0) −B (u, 0))
v = 1 v = 1

When,

[Equation 18]
E (u, 0)
= C (u, 0) -B (u, 0) · Q B / Q C, v = 1, ..., 7,

(B2) If Equation 17 is not satisfied,
[Equation 19]
E (u, 0) = C (u, 0)
It is.

Furthermore, for all other coefficients,
[Equation 20]
E (u, v) = C (u, v)
It is.

  In the above-described eighth embodiment, the DCT transform coefficient prediction process is performed on the quantized transform coefficient data by the unit 2040. However, the present invention is not limited to this, and is similar to the sixth embodiment in FIG. Alternatively, the conversion may be performed on transform coefficient data that is not quantized. In this case, in the corresponding image prediction decoding apparatus, in FIG. 25, the inverse quantization unit 2056 is moved and inserted into the inverse scan unit 2052 and the adder 2053.

  Hereinafter, a modified example of the eighth embodiment will be described.

(A) The block sampling unit 2031 determines that the pixels of the two-dimensional array in the group of four blocks consist of odd-numbered pixels in odd-numbered rows in the first block, and odd-numbered pixels in odd-numbered rows in the second block. The pixels are alternated so that they consist of even-numbered pixels in a row, the third block consists of odd-field pixels in even-numbered rows, and the fourth block consists of even-numbered pixels in even-numbered rows. May be included.
(B) the prediction block is selected from blocks previously stored in the block memory and previously reconstructed and located adjacent to the current block being coded, and all coefficients in the block are selected. Data may be selected.
(C) the prediction block is selected from blocks previously stored in the block memory and previously reconstructed and located adjacent to the current block being coded, and a predetermined subset It may be selected as coefficient data of a block.

(D) the prediction block is selected from blocks previously stored in the block memory and previously restored, which are positioned adjacent to the upper and left sides of the coded current block; Only the coefficient data in the top row and the leftmost column of the block may be used, and the remaining coefficient data may be set to zero.
(E) the predicted block is stored in the block memory and selected from previously restored blocks according to the criteria described above;
It is determined that the image prediction encoding device and the image prediction decoding device perform communication by using only the subset including one or more coefficient data from the top row or the leftmost column of the block. Is also good.
(F) the predicted block is stored in the block memory and selected from previously restored blocks according to the criteria described above;
The image predictive coding apparatus determines that only the subset including one or more coefficient data from the top row or the leftmost column of the block is used, and indicates the determined subset and the number of coefficient data. The flag may be notified to the image prediction decoding device by periodically inserting the flag into the data transmitted to the image prediction decoding device.

(G) the prediction block is stored in the block memory and selected from previously restored blocks according to the criteria described above;
The coefficient data of each block may be multiplied by a ratio equal to the ratio between the quantization step size of the current block to be encoded and the quantization step size of the prediction block.
(H) the predicted block is stored in the block memory and selected from previously restored blocks according to the criteria described above;
The coefficient data of each block may be weighted with different weighting functions.
(I) the prediction block is stored in the block memory and selected from previously restored blocks according to the above criteria;
A predetermined conversion operation may be performed on the coefficient data of each block. (J) The prediction block may be obtained as a weighted average of previously restored blocks stored in the block memory and located adjacent to the current block to be encoded.

(K) Scan method
(I) a horizontal scan in which coefficient data is scanned from left to right, line by line, starting at the top row and ending at the bottom row;
(Ii) a vertical scan in which coefficient data is scanned starting from the leftmost column and ending with the rightmost column for each column from the top row to the bottom row;
(Iii) The coefficient data may include at least one of a zigzag scan that is diagonally scanned from the leftmost coefficient data in the uppermost row to the rightmost coefficient data in the lowermost row.

(L) the predicted block is stored in the block memory and selected from previously restored blocks according to the criteria described above;
The prediction mode of the prediction block is
(I) a first mode in which only the uppermost and leftmost coefficient data representing the average value of the block, referred to as a DC coefficient, from a block located above the current block to be processed is used for prediction;
(Ii) a second mode in which only DC coefficients from a block located on the left side of the current block to be processed are used for prediction;
(Iii) a third mode in which the DC coefficient and zero or more AC coefficients including high-frequency components from the top row of the block located above the current block to be processed are used for prediction;
(Iv) a fourth mode in which a DC coefficient and zero or more AC coefficients including high-frequency components from the leftmost column of a block located on the left side of the current block to be processed are used for prediction;
Including at least one prediction mode of
The coefficient data of the prediction error may be scanned by a zigzag scan method.

(M) the predicted block is stored in the block memory and selected from previously restored blocks according to the criteria described above;
The coefficient data of the prediction error is scanned according to one of the scanning methods described above,
The prediction mode for predicting the coefficient data of the prediction error is as follows:
(I) A first mode in which only DC coefficients in a block located above a current block to be processed are used for prediction, and a scan process is performed by zigzag scan on coefficient data of the prediction error. ,
(Ii) A second mode in which only DC coefficients in a block located on the left side of the current block to be processed are used for prediction, and a scan process is performed on the coefficient data of the prediction error by zigzag scan. ,
(Iii) DC coefficients and 0 or more AC coefficients including high-frequency components in the top row of the block located above the current block to be processed are used for prediction, and the coefficient data of the prediction error is A third mode in which scan processing is performed in horizontal scanning;
(Iv) The DC coefficient in the leftmost column of the block located on the left side of the current block to be processed and zero or more AC coefficients including high-frequency components are used for prediction, and the coefficient data of the prediction error is On the other hand, a fourth mode in which scan processing is performed by vertical scanning,
May be included.

(N) When forming a two-dimensional array of pixels from a plurality of groups of four interleaved blocks based on the decoded image data and restoring the original image data, an odd-numbered row Are obtained from the first block, even-numbered pixels in the odd-numbered row are obtained from the second block, and odd-numbered pixels in the even-numbered row are obtained from the third block. The deinterleaving process may be performed on the decoded image data so that the even-numbered pixels in the even-numbered rows are obtained from the fourth block.
(O) The image prediction encoding device and the image prediction decoding device may determine the prediction mode using the same predetermined rule.
(P) The image prediction encoding device and the image prediction decoding device may determine the scanning method using the same predetermined rule.

  As described above, according to the third embodiment group according to the present invention, it is very effective to reduce or eliminate redundancy in the DCT transform domain beyond adjacent blocks, Can be reduced, and as a result, the coding efficiency can be greatly improved. This is also useful as a tool in new video compression algorithms.

  In the above embodiments, the image predictive encoding device and the image predictive decoding device have been described. However, the present invention is not limited to this. The image prediction encoding method may include a step in which each step is replaced by a step, or an image prediction decoding method including a step in which components such as each unit and each unit in the image prediction decoding apparatus are replaced with each step It may be. In this case, for example, each step of the image prediction encoding method and / or the image prediction decoding method is stored in a storage device as a program, and a controller such as a microprocessor unit (MPU) and a central processing unit (CPU) By executing the program, the image prediction encoding process and / or the image prediction decoding process is performed.

  Further, the present invention may be a recording medium recording a program including each step in the image prediction encoding method and / or the image prediction decoding method. The recording medium has a disk shape in which a recording area is divided into sector shapes or a recording area is divided into blocks in a spiral shape, for example, an optical disk or a magneto-optical disk such as a CD-ROM or a DVD, or And a magnetic recording disk such as a floppy disk.

FIG. 1 is a block diagram illustrating a configuration of an image prediction encoding device according to a first embodiment of the present invention. FIG. 2 is a schematic diagram when an input image input to the image predictive encoding device in FIG. 1 is divided into 8 × 8 blocks. FIG. 2 is a schematic diagram when an input image input to the image predictive encoding device in FIG. 1 is divided into triangular regions. FIG. 2 is a block diagram illustrating a configuration of a first embodiment of a prediction signal generator used in the image prediction encoding device in FIG. 1. FIG. 6 is a block diagram illustrating a configuration of a second embodiment of the prediction signal generator used in the image prediction encoding device in FIG. 1. FIG. 11 is a block diagram illustrating a configuration of a third embodiment of the prediction signal generator used in the image prediction encoding device in FIG. 1. FIG. 13 is a block diagram illustrating a configuration of a fourth embodiment of the prediction signal generator used in the image prediction encoding device in FIG. 1. It is a block diagram showing the composition of the picture prediction coding device which is a 2nd embodiment concerning the present invention. FIG. 9 is a schematic diagram illustrating an example of an input image input to the image predictive encoding device in FIGS. 1 and 8 and having significant pixels. FIG. 9 is a schematic diagram illustrating an example of an input image input to the image predictive encoding device in FIGS. 1 and 8 and having significant pixels. FIG. 9 is a schematic diagram illustrating an example of an input image input to the image predictive encoding device of FIGS. 1 and 8 and having an insignificant pixel. It is a block diagram showing the composition of the picture prediction decoding device which is a 3rd embodiment concerning the present invention. It is a block diagram showing the composition of the picture prediction decoding device which is a 4th embodiment concerning the present invention. FIG. 11 is a block diagram illustrating a configuration of a conventional image prediction encoding device. FIG. 5 is a schematic diagram of an image for explaining an adaptive DCT transform area for intra prediction. It is a block diagram showing the composition of the picture prediction coding device which is a 5th embodiment concerning the present invention. It is a block diagram showing the composition of the picture prediction coding device which is a 6th embodiment concerning the present invention. FIG. 18 is a block diagram illustrating a configuration of a DCT transform region prediction circuit in FIGS. 16 and 17. FIG. 19 is a schematic diagram of an image illustrating an example of a coding method of DC / AC prediction in the DCT transform domain prediction circuit in FIG. 18. It is a block diagram showing the composition of the picture prediction decoding device which is a 7th embodiment concerning the present invention. 21 is a flowchart illustrating a decoding method of DC / AC prediction in the image prediction decoding device of FIG. 20. FIG. 11 is a block diagram illustrating a configuration of a conventional image prediction encoding device. FIG. 11 is a block diagram illustrating a configuration of a conventional image prediction decoding device. It is a block diagram showing the composition of the picture prediction coding device which is an 8th embodiment concerning the present invention. It is a block diagram showing the composition of the picture prediction decoding device which is an 8th embodiment concerning the present invention. It is a mimetic diagram of a picture which shows a structure of a macroblock of a frame and a block in an 8th embodiment, and shows a block prediction method. It is a mimetic diagram of an image for explaining an order of a horizontal scan used for a coefficient scan in an 8th embodiment. It is a mimetic diagram of an image for explaining an order of a vertical scan used for a coefficient scan in an 8th embodiment. It is a mimetic diagram of an image for explaining an order of a zigzag scan used for a coefficient scan in an 8th embodiment. It is a flowchart which shows the mode determination process used in 8th Embodiment. It is a schematic diagram of the image which shows the relationship of the block in the implicit mode determination of 8th Embodiment.

Explanation of reference numerals

101 ... input terminal,
102 a first adder,
103 ... encoder,
104 DCT converter,
105 ... Quantizer,
106 output terminal,
107 ... decoder,
108 ... Inverse quantizer,
109 ... Inverse DCT converter,
110 ... second adder,
111 ... line memory,
112 ... prediction signal generator,
200 ... block,
300, 301 ... triangle,
401, 402 ... generator,
403, 404 ... image data,
500 ... adder,
601, 602, 603: error calculator,
604 ... comparator,
605 ... switch,
700: motion detector,
701: motion compensator,
702: frame memory,
703: optimal mode selector,
800, 804 ... shape curve,
802, 805, 810 ... small area to be processed,
808 ... curve,
901, input terminal,
902: Data analyzer,
903: Decoder,
904: inverse quantizer,
905: inverse DCT converter,
906 ... adder,
907 ... output terminal,
908 ... controller,
909: motion compensator,
910... A prediction signal generator;
911: Line memory,
912: Frame memory,
913 ... switch,
922... A prediction signal generator;
923: motion compensator,
990 ... shape decoder,
1001 ... Block sampling unit,
1002 ... motion detection unit,
1003 ... compensation unit,
1004 ... DCT converter,
1005 ... Quantization unit,
1006 ... entropy coding unit,
1007 ... Rate controller,
1008, 1009 ... unit,
1010: Local decoding frame memory
1011: Reference frame memory,
1012 ... Block sampling unit,
1013 ... adder,
1014 ... DCT conversion unit,
1015 ... Quantization unit,
1016 ... adder,
1017: DCT transform domain prediction unit,
1018 ... Block memory,
1019 ... adder,
1020 ... entropy VLC coding unit,
1021... Inverse quantization unit,
1022... Inverse DCT transform unit,
1023 ... adder,
1024: frame memory,
1025: motion detection and compensation unit,
1026 ... Block sampling unit,
1027 ... adder,
1028 DCT conversion unit,
1029 ... adder,
1030 ... Quantization unit,
1031: DCT transform area prediction unit,
1032: block memory,
1033: inverse quantization unit,
1034 ... entropy VLC encoding unit,
1035 ... adder,
1036: inverse DCT conversion unit,
1037 ... adder,
1038: Frame memory,
1040 ... Block memory,
1041 ... unit,
1042 ... No-Pred block,
1043 ... Up-Pred block,
1044: Left-Pred block,
1045 ... Other-Pred block,
1048, 1049, 1050 ... unit,
1051... Entropy VLD decoding unit
1052 ... adder,
1053: DCT transform area prediction unit,
1054: block memory,
1055: inverse DCT conversion unit,
1056 ... adder,
1057 ... Motion detection and compensation unit,
1059: inverse quantization unit,
1101, 1102 ... current block,
2031 ... Block sampling unit,
2032 ... adder,
2033 DCT conversion unit,
2034 ... Quantization unit,
2035 ... adder,
2036: H / V / Z scan unit,
2037 ... entropy VLC encoding unit,
2038 ... adder,
2039 ... block memory,
2040: DCT transform area prediction unit,
2041... Inverse quantization unit,
2042 ... Inverse DCT transform unit,
2043 ... adder,
2044 ... frame memory,
2045: motion detection and compensation unit,
2051 ... variable length decoder unit,
2052 ... H / V / Z scan unit,
2053 ... adder,
2054 ... Block memory,
2055: DCT transform area prediction unit,
2056: inverse quantization unit,
2057: inverse DCT conversion unit,
2058 ... adder,
2059 ... frame memory,
2060 ... Motion detection and compensation unit,
2061 ... Block memory,
2062 ... subtraction unit
2063 ... H / V / Z scan unit,
2064 ... entropy coding unit,
2065: comparison unit,
2066 ... selection unit,
B0: current block,
B1 ... upper left block,
B2: Upper block,
B3: Upper right block,
B4: Left block.

Claims (6)

A conversion step of converting the blocked image data into a two-dimensional sequence of conversion coefficients;
A quantization step of quantizing the transformed coefficients of the two-dimensional sequence to obtain a quantized transform coefficient;
A predictive block selecting step of adaptively selecting a predictive block to predict a quantized DC coefficient of the current block from either the upper block or the left block adjacent to the current block;
DC coefficient prediction for obtaining a DC coefficient prediction error by predicting a quantized DC coefficient of a current block from a quantized DC coefficient of an adjacent block adaptively selected from either the upper block or the left block Steps and
An AC coefficient prediction step of predicting a quantized AC coefficient of the current block from the quantized AC coefficients of the selected block for the DC coefficient prediction to obtain an AC coefficient prediction error; And an encoding step of performing variable length encoding of the AC coefficient prediction error.   2. The image prediction encoding method according to claim 1, wherein bit information indicating whether or not the AC coefficient prediction has been performed at the time of encoding is output as an encoded bit stream. The AC coefficient prediction of the current block is
In the case of selecting the left block as the prediction block during the DC coefficient prediction of the current block, the AC coefficient prediction is performed using the quantized AC coefficient in the first column of the left block as a prediction value,
In the case of selecting the upper block as the prediction block during the DC coefficient prediction of the current block, the AC coefficient prediction is performed using the quantized AC coefficient in the first row of the upper block as a prediction value. The image predictive encoding method according to claim 1, wherein: An image prediction encoding device that encodes image data,
A converter for converting the blocked image data into a two-dimensional sequence of conversion coefficients;
A quantizer that quantizes the transform coefficients of the two-dimensional sequence to obtain a quantized transform coefficient;
Predictive block selecting means for adaptively selecting a predictive block for predicting the quantized DC coefficient of the current block from either the upper block or the left block adjacent to the current block;
DC coefficient prediction for obtaining a DC coefficient prediction error by predicting a quantized DC coefficient of a current block from a quantized DC coefficient of an adjacent block adaptively selected from either the upper block or the left block Means,
AC coefficient prediction means for predicting the quantized AC coefficient of the current block from the quantized AC coefficient of the selected block for the DC coefficient prediction to obtain an AC coefficient prediction error, and the DC coefficient prediction error And an encoding means for performing variable length encoding of the AC coefficient prediction error.   The image prediction encoding apparatus according to claim 4, wherein bit information indicating whether or not the AC coefficient prediction is being performed at the time of encoding is output as an encoded bit stream. The AC coefficient prediction of the current block is
In the case of selecting the left block as the prediction block during the DC coefficient prediction of the current block, the AC coefficient prediction is performed using the quantized AC coefficient in the first column of the left block as a prediction value,
In the case of selecting the upper block as the prediction block during the DC coefficient prediction of the current block, the AC coefficient prediction is performed using the quantized AC coefficient in the first row of the upper block as a prediction value. The image prediction encoding apparatus according to claim 4, wherein:

Images