JP3343554B1 - Image prediction decoding method and image prediction encoding device - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To reduce redundancy in a block and to decode image data more efficiently as compared with the related art. SOLUTION: AC coefficients of a current block (C) are predicted using quantized AC coefficients of adaptively selected prediction blocks. The ratio between the quantization step size of the current block (C) and the quantization step size of the selected prediction block is calculated by calculating the quantized AC coefficient of the prediction block selected for the AC coefficient prediction of the current block (C). And scale. The prediction result of the AC coefficient prediction is subjected to variable-length encoding, the quantized AC coefficient of the current block (C) is restored using the prediction result, and the quantized AC coefficient of the restored current block (C) is calculated. Remember. When coding a block to be coded later than the current block (C), the stored quantized AC coefficients are used as the quantized AC coefficients of the selected prediction block.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention 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 that is 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.

[0002]

2. Description of the Related Art Efficient storage or transmission of digital images requires compression encoding. As a method for compressing and encoding digital images, JPEG (Joint Ph
otographic Experts Group) and MPEG (Motion Pictu
In addition to discrete cosine transform (hereinafter, referred to as DCT transform) represented by re-Experts Group, there are waveform coding methods such as subband coding, wavelet coding, and fractal coding. In order 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 ones.
Processing is performed by dividing the macroblock into 6 × 16 macroblocks. One macroblock is further divided into 8 × 8 blocks,
Quantization is performed after performing DCT transform processing of × 8. This is called intra-frame coding.

On the other hand, by a motion detection method such as block matching, a prediction macroblock having the smallest error as a target macroblock is detected from another frame adjacent to time, and the detected prediction macroblock is determined as a target macroblock. The block is subtracted from the block to generate a difference macroblock, subjected to an 8 × 8 DCT transform, and then quantized. This is called inter-frame coding, and the predicted macroblock is called a time-domain predicted signal. In this way, 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.

[0006] Since two spatially close pixel values are close to each other, the predicted 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. It is necessary to rapidly generate a spatial domain prediction signal from these two factors. This is because the pixel value is used for generating 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.

[0008] By the way, image data is encoded by JPE
G, MPEG1, H.261, MPEG2 and H.263
Has been widely used for many international standards such as. 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.

[0009] Encoding of image data for a moving image includes intra-frame encoding and predictive frame encoding. Here, intra-frame encoding refers to intra-frame encoding of one frame within a screen. For example, M
In a typical hybrid coding system, such as the PEG1 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. P-frames are 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 frame is 1
It is encoded by using motion detection and compensation using information from the previous frame and information from the subsequent frame 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 characteristics of I-frames, P-frames and B-frames are different, their compression methods are also different. I-frames require more bits than P- 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. In general, I, P and B
The ratio of the number of bits used for the frame is 6: 3: 1. Therefore, an I-frame uses about 420 Kbits / s,
B frames use about 70 Kbits / s. Because B
This is because the frame is well predicted from both directions.

FIG. 14 is a block diagram showing a configuration of a conventional image predictive coding apparatus. 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 encoding, first, as shown in FIG. 14, a block sampling process 1001 is performed on an input digital image signal. Next, DCT transform processing 1004 is performed on these blocks after block sampling processing 1001.
Is performed, quantization processing 1005 and run-length Huffman variable length coding (VLC) are performed.
ng; entropy coding) processing 1006 is executed.
On the other hand, in predictive frame coding, a motion compensation process 1003 is performed on the input digital image,
Then, DCT transform processing 1004 is performed on the motion-compensated block (that is, the predicted block). Next, quantization processing 1005 and run-length Hoffman VLC encoding (entropy encoding) processing 10
06 is executed.

Block-based DCT transform processing 1004
Removes or reduces spatial redundancy in the block being processed, and the motion detection and compensation process 10
02,1003 is known from conventional image coding techniques to remove or reduce temporary redundancy between adjacent frames. Further, 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 the frame of the 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 the current image coding method, DCT
The conversion process 1004 or other conversion processes are performed on a block basis due to hardware implementation and computational constraints.

The 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 by using intra-frame coding, which always consumes a large number of bits.

In addition, the block-based DCT transform removes or reduces spatial redundancy in the block being processed, and the motion estimation and compensation process allows for Eliminating or reducing temporary redundancy is known from current image coding techniques. Zigzag scan and run-length Hoffman VLC performed after DCT transform processing and quantization processing
The encoding process or other entropy encoding process removes the statistical redundancy in the quantized DCT transform coefficients, but is still 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 methods do 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, D
The prediction of the C coefficient 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 coding. No attempt has been made to adapt the scan based on the contents of the block.

FIG. 22 is a block diagram showing the configuration of a conventional image predictive coding apparatus. In FIG. 22, a conventional image prediction encoding apparatus includes a block sampling unit 2001, a DCT transform unit 2003, a quantization unit 2004, and a zigzag scan unit 200.
5 and an entropy coding unit 2006.
In this specification, the term “unit” means a circuit device.

In intra-frame coding (ie, 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 Quantization process 2004, zigzag scan process 200
5 and the entropy coding processing 2006 are sequentially performed. 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,
Next, a prediction error is obtained by the adder 2002 by subtracting the detection value from the unit 2011 from the image data from the block sampling 2001. Further, a DCT transform process 2003 is performed on the prediction error, followed by a quantization process 2004, a zigzag scan process 2005, and an entropy encoding process 2006.
Is performed in the same manner as intra-frame coding.

In the local decoder provided in the image predictive encoding apparatus shown in FIG.
The T conversion processing is executed in units 2007 and 2008. In intra-frame coding, motion-detected and compensated predictions are stored in units 2007 and 20
08 is added to the prediction error reconstructed by 08 by an adder 2009, and the added value means locally decoded image data, and the decoded image data is
It 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 the configuration of a conventional image prediction decoding apparatus. The bitstream is
Variable Length Decoding (VLD)
Unit (or entropy decoding unit) 2021
Then, an inverse quantization process and an inverse DCT transform process are performed on the decoded image data in the units 2023 and 2024. In inter-frame coding, the motion-detected and compensated predicted values formed in unit 2027 are added to adder 2025
Is added to the reconstructed prediction error to form local decoded image data. The locally decoded image data is stored in the frame memory 1026 of the local decoder.
Is stored.

[0026]

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

A first object of the present invention is to provide an image prediction coding 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. Is to provide.

A second object of the present invention is to eliminate the redundancy in a block as compared with the conventional image predictive coding apparatus and image predictive decoding apparatus, and to improve the efficiency of image prediction. An object of the present invention is to provide an image prediction encoding apparatus and method capable of encoding or decoding data, and an image prediction decoding apparatus and method.

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

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

[0031]

According to the present invention, there is provided an image predictive decoding apparatus comprising: a blocking unit configured to block an image signal into a plurality of blocks; and an image signal of the block obtained by the blocking unit. Transforming means for transforming into DCT coefficients of a dimensional sequence, quantizing means for quantizing the DCT coefficients transformed by the transforming means, and an upper block (A) or a left block (B) adjacent to the current block (C). Either of the A of the current block (C)
Prediction block selection means for adaptively selecting a prediction block for predicting a C coefficient; and a quantized AC of the prediction block selected by the prediction block selection means.
An AC coefficient prediction unit that performs AC coefficient prediction of the current block (C) using the coefficient; and a quantized AC coefficient of the prediction block selected for the AC coefficient prediction of the current block (C). Scaling means for scaling using a ratio between the quantization step size of the current block (C) and the quantization step size of the selected prediction block, and a variable length encoding means for performing variable length coding on the prediction result of the AC coefficient prediction means. Long encoding means;
AC coefficient restoring means for restoring the quantized AC coefficient (QFx) of the current block (C) using the prediction result of the C coefficient estimating means, and the current block (C) restored by the AC coefficient restoring means. ) Quantized A
Storage means for storing C coefficients, and when encoding a block to be encoded later than the current block (C), the quantized A of the selected prediction block is encoded.
As the C coefficient, a quantized AC coefficient stored in the storage means is used.

Further, in the image predictive decoding method according to the present invention, an image signal is divided into a plurality of blocks, and the image signal of the block is converted into a two-dimensional DCT.
And transforms the transformed DCT coefficients into coefficients,
A prediction block for predicting the AC coefficient of the current block (C) is adaptively selected from either the upper block (A) or the left block (B) adjacent to the current block (C). The AC coefficient of the current block (C) is predicted using the quantized AC coefficient of the prediction block, and A of the current block (C) is predicted.
The quantized AC coefficients of the prediction block selected for C coefficient prediction are scaled using a ratio of the quantization step size of the current block (C) to the quantization step size of the selected prediction block. Then, the prediction result of the AC coefficient prediction is variable-length coded, and the quantized AC coefficient of the current block (C) is restored using the prediction result, and the quantization of the restored current block (C) is performed. When encoding a block to be encoded later than the current block (C), the stored AC coefficient is stored as the quantized AC coefficient of the selected prediction block. It is characterized by using the obtained AC coefficient.

An image predictive coding apparatus according to the first invention comprises:
Dividing means for dividing the input coded image data into image data of a plurality of small areas adjacent to each other; and a small area to be processed among the image data of a plurality of adjacent small areas divided by the dividing means. When encoding the image data of the above, the image data of the reproduced small area reproduced adjacent to the image data of the small area to be processed is set as the image data of the intra prediction small area of the small area to be processed, The image data of the intra-screen prediction small area is set as the image data of the optimal prediction small area, and the image data of the difference small area which 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, coding means for coding the image data of the small difference area generated by the generating means, and image data of the small difference area coded by the coding means. Decoding means for decoding the data, and adding the image data of the small difference area decoded by the decoding means to the image data of the optimal prediction small area to generate the reproduced small area image data. Second
Generating means.

The image predictive encoding apparatus according to the second invention is a division means for dividing 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, the encoding is performed from the image data of the reproduced small area reproduced adjacent to the image data of the small area to be processed. Only the significant image data indicated by the input significant signal indicating whether the image data is significant is regarded as the image data of the intra-screen predicted small area of the small area to be processed, and the image of the intra-screen predicted small area is used as the image data. A first raw data generating image data of a difference small area which is a difference between the image data of the small area to be processed and the image data of the optimum prediction small area, using the data as image data of the optimal prediction small area. Means, encoding means for encoding the image data of the small difference area generated by the first generation means, and decoding means for decoding the image data of the small difference area encoded by the encoding means And second generating means for generating image data of a reproduced small area by adding the image data of the difference small area decoded by the decoding means to the image data of the optimal predicted small area. Prepare.

Further, an image predictive decoding apparatus according to a third aspect of the present invention includes an analyzing means for analyzing an input coded image data sequence and outputting an image difference signal, and a difference output from the analyzing means. Decoding means for decoding the image data of the reproduction difference small area from the image signal, a line memory for storing image data for generating image data of a predetermined intra prediction small area, and an image from the line memory By executing a prediction signal generation process on the data, 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 image data of the intra-screen prediction small area is processed. Means for outputting image data of the optimal prediction small area, image data of the reproduction difference small area from the decoding means, and image data of the optimal prediction small area from the generation means. By adding the data, it outputs the image data for generating the intra-frame prediction small region of the addition result, an adding means for storing in said line memory.

Still further, the image prediction decoding apparatus according to the fourth invention analyzes the input coded image data sequence, and outputs an image difference signal, a motion vector signal, and a control signal. Analysis means; decoding means for decoding the difference image signal output from the analysis means into image data of a reproduced difference small area; and motion compensation means based on the control signal output from the analysis means. Means for outputting a switching signal for controlling the means to selectively operate, a frame memory for storing predetermined reproduced image data, and image data for generating image data of a predetermined intra-screen predicted small area By executing a motion compensation process on an input motion vector signal in response to a switching signal from the control means, A motion compensation means for generating image data of the temporal prediction small area from the memory, and outputting the image data as the image data of the optimal prediction small area; and, in response to a switching signal from the control means, for the image data from the line memory. Executing the prediction signal generation processing, the reproduced image data adjacent to the image data of the reproduction difference small area is set as the image data of the intra prediction small area, and the image data of the intra prediction small area is optimally predicted. Generating means for outputting the image data of the small area, image data of the reproduced difference small area from the decoding means, and the optimal predicted small area from the generating means; Output and store the reproduced image data in the frame memory, and generate only the image data for generating the image data of the intra prediction small area. An adding means for storing in said line memory.

An image predicting and decoding apparatus according to a fifth aspect of the present invention includes an analyzing means for analyzing an input coded image data sequence and outputting a compressed shape signal and an image difference signal; First decoding means for decoding the compressed shape signal output from the means into a reproduction shape signal, and second decoding means for decoding the difference image signal output from the analysis means into image data of a reproduction difference small area. Decoding means, a line memory for storing image data for generating image data of a predetermined intra-screen prediction small area, and performing a prediction signal process on the image data from the line memory,
From the reproduced image data adjacent to the image data of the reproduction difference small area, only significant image data indicated by the reproduction shape signal is set as the image data of the intra prediction small area, and the Generating means for outputting image data as image data of an optimal prediction small area; image data of a reproduction difference small area from the second decoding means;
By adding the optimum predicted small area from the generating means, the image data of the addition result is output, and only the image data for generating the image data of the intra-screen predicted small area is stored in the line memory. Adding means.

Further, the image predictive decoding device according to the sixth aspect of the present 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. Analyzing means for outputting a compressed shape signal output from the analyzing means into a reproduced shape signal, and a differential image signal output from the analyzing means for converting a reproduced difference signal into a reproduced differential signal. Second decoding means for decoding the area, and 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 reproduced image data, a line memory for storing image data for generating image data for a predetermined intra-screen predicted small area, and a frame output from the control means. Generating the image data of the temporal prediction small area by executing 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 input signal. A motion compensation unit that outputs the image data of the optimal prediction small area, and a prediction signal process performed on the image data from the line memory in response to a switching signal output from the control unit. From among the reproduced image data adjacent to the image data of the reproduction difference small area, only significant image data indicated by the reproduction shape signal is set as the image data of the intra prediction small area,
Generating means for outputting the image data of the intra prediction small area as image data of the optimal prediction small area; image data of the reproduction difference small area from the second decoding means; By adding the areas, the reproduced image data of the addition result is output, the reproduced image data is stored in the frame memory, and only the image data for generating the intra-screen predicted small area is stored in the line memory. Storage means for storing.

An image predictive coding apparatus according to a seventh invention comprises:
Sampling means for sampling the input image signal into image data of a plurality of blocks each including a two-dimensional array of pixel values; and converting the image data of the block sampled by the sampling means into coefficient data of a predetermined conversion area. A conversion unit; a block memory for storing the restored coefficient data of the block; and a 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. Prediction means for forming coefficient data of a plurality of prediction blocks with respect to, and coefficient data of the most efficient prediction block among coefficient data of the plurality of prediction blocks formed by the prediction means are determined, selected and output. And an indicator representing the selected prediction block in the form of an indication bit. Determining means for transmitting to the image prediction decoding apparatus, and subtracting the coefficient data of the prediction block selected by the determining means from the coefficient data of the current block at the present time, thereby outputting coefficient data of the prediction error of the subtraction result A first adder, a quantizer for quantizing the prediction error coefficient data output from the first adder, and entropy coding of the prediction error coefficient data from the quantizer to perform encoding. Encoding means for transmitting the decoded prediction error coefficient data to the image prediction decoding apparatus, and inverse quantization for dequantizing the prediction error coefficient data from the quantization means and outputting the restored block coefficient data. Adding the coefficient data of the prediction block output from the determining means to the coefficient data of the prediction error output from the inverse quantization means. By outputting the restored coefficient data of the block and inversely transforming the coefficient data of the block output from the second addition means stored in the block memory and the second addition means, Inverse conversion means for generating image data of the block.

An image predictive encoding apparatus according to an eighth aspect of the present invention provides a sampling predictor for sampling 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 the plurality of blocks into coefficient data of a predetermined conversion area, and quantization means for quantizing the coefficient data of the conversion area from the conversion means,
A block memory for storing the restored coefficient data of the block; and a plurality of coefficient data for the block converted by the conversion means, based on the coefficient data of the previously reconstructed block stored in the block memory. Predicting means for forming coefficient data of a prediction block of the plurality of prediction blocks, and among the coefficient data of the plurality of prediction blocks formed by the prediction means, determine and select and output the coefficient data of the most efficient prediction block; Deciding means for transmitting an indicator representing the selected prediction block to the image prediction decoding apparatus in the form of a designation bit, and subtracting the coefficient data of the prediction block selected by the deciding means from the coefficient data of the current block at the present time. Thereby, the first adding means for outputting coefficient data of the prediction error of the subtraction result,
Encoding means for entropy encoding the coefficient data of the prediction error from the first adding 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 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, and stored in the block memory. A dequantizing means for dequantizing and outputting the coefficient data of the current block output from the second adding means, and inversely transforming the coefficient data of the current block from the dequantizing means. And inverse conversion means for generating image data of the restored block.

Further, the image predictive coding apparatus according to the ninth aspect of the present invention comprises a sampling means for sampling the input image signal into image data of a plurality of blocks each including a two-dimensional array of pixel values, By performing motion compensation processing on the image data of (i), the compensation means for generating and outputting the image data of the prediction error of the motion-compensated block, and the image data of the block output from the sampling means, First adding means for subtracting the prediction error image data of the block output from the compensating means and outputting the image data of the block resulting from the subtraction; and calculating the block image data output from the first adding means. A conversion unit that converts the coefficient data of the predetermined conversion area into coefficient data, a block memory that stores the coefficient data of the restored block, A prediction unit configured to form coefficient data of a plurality of prediction blocks based on coefficient data of a block reconstructed before and stored in the block memory, based on coefficient data of the block converted by the conversion unit; Among 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 represented in the form of an indication bit. Determining means for transmitting to the image prediction decoding apparatus, and by subtracting the coefficient data of the prediction block selected by the determining means from the coefficient data of the current block at the present time,
Second adding means for outputting coefficient data of a prediction error as a result of the subtraction, quantizing means for quantizing coefficient data of the prediction error output from the second adding means, and prediction error from the quantization means Encoding means for entropy encoding the coefficient data of the prediction error, and transmitting the encoded prediction error coefficient data to the image prediction decoding apparatus; and dequantizing and restoring the prediction error coefficient data from the quantization means. Dequantizing means for outputting the coefficient data of the block thus obtained, and adding the coefficient data of the prediction block output from the determining means to the coefficient data of the prediction error output from the dequantizing means, thereby performing the restoration. Output the coefficient data of the block obtained and store it in the third block memory.
, An inverse transform unit for inversely transforming the coefficient data of the block output from the third adder unit to generate image data of a restored block, and a restored image data from the inverse transform unit. A fourth adding unit that outputs the restored block image data to the compensation unit by adding the motion-compensated block prediction error image data output from the compensation unit to the block image data; Is provided.

Still further, the image predictive encoding apparatus according to the tenth aspect of the present invention is characterized in that a sampling means for sampling an input image signal into a plurality of blocks of image data including pixel values in a two-dimensional array, By performing motion compensation processing on the image data of (i), the compensation means for generating and outputting the image data of the prediction error of the motion-compensated block, and the image data of the block output from the sampling means, First adding means for subtracting the prediction error image data of the block output from the compensating means and outputting the image data of the block resulting from the subtraction; and calculating the block image data output from the first adding means. Conversion means for converting coefficient data of a predetermined conversion area into coefficient data of the predetermined conversion area; and quantization means for quantizing coefficient data of the conversion area from the conversion means. A block memory for storing the coefficient data of the restored block, and a coefficient data of the block converted by the conversion means based on the coefficient data of the previously reconstructed block stored in the block memory. A prediction unit that forms coefficient data of a plurality of prediction blocks; and a coefficient data of a prediction block having the highest efficiency among coefficient data of the plurality of prediction blocks formed by the prediction unit. Determining means for transmitting an indicator representing the selected prediction block to the image prediction decoding device in the form of an indication bit; and subtracting the coefficient data of the prediction block selected by the determining means from the coefficient data of the current block at the present time. By doing so, the second addition means for outputting coefficient data of the prediction error of the subtraction result, and the second addition means Encoding means for entropy encoding the prediction error coefficient data from the means, and transmitting the encoded prediction error coefficient data to the image prediction decoding device; and prediction error coefficient data from the second addition means. A third adder for restoring and outputting the quantized coefficient data of the current block by adding the coefficient data of the prediction block output from the determiner, and storing the data in the block memory; The inverse quantization means for inversely quantizing the coefficient data of the current block output from the third addition means and outputting the inversely quantized data, and the coefficient data of the current block output from the inverse quantization means are inversely transformed to be restored. An inverse transform unit for generating image data of the block, and outputting the image data of the restored block from the inverse transform unit to the image data of the compensation unit. A fourth adding unit that outputs the restored block image data to the compensation unit by adding the image data of the prediction error of the motion-compensated block.

An image predictive decoding apparatus according to an eleventh aspect of the present invention is an image predictive decoding apparatus provided corresponding to the image predictive encoding apparatus according to the seventh aspect of the present invention. Extracting means for extracting an instruction bit from the received data, a block memory for storing coefficient data of a reconstructed block, and storing in the block memory based on a prediction block indicated by the instruction bit extracted by the extracting means. Another prediction means for generating and outputting coefficient data of a prediction block with respect to the coefficient data of the current block included in the received data, using the coefficient data of the previously restored block, Decoding means for entropy decoding the data and outputting decoded prediction error coefficient data; and Inverse quantization means for inversely quantizing and outputting the prediction error coefficient data, and the prediction block coefficient data output from the another prediction means to the prediction error coefficient data output from the inverse quantization means. By the addition, the coefficient data of the current block at the current time is restored and output, and the coefficient data of the current block output from the third addition means and the third addition means stored in the block memory are inverted. And another inverse conversion means for outputting the converted and restored image data of the current block.

An image predictive decoding device according to a twelfth aspect is an image predictive decoding device provided corresponding to the image predictive encoding device according to the eighth aspect, wherein the image predictive encoding device Extraction means for extracting the instruction bits from the received data received from, a block memory for storing the coefficient data of the reconstructed block, and a prediction block indicated by the instruction bits extracted by the extraction means,
Another prediction for generating and outputting coefficient data of a prediction block with respect to coefficient data of a current block included in the reception data using coefficient data of a previously restored block stored in the block memory. Means for entropy decoding the received data, and decoding means for outputting decoded coefficient data of the prediction error;
By adding the coefficient data of the prediction block output from the prediction unit to the coefficient data of the prediction error output from the decoding unit, the current block coefficient data of the current block is restored and output. A third adder for storing in the memory, an inverse quantizer for inversely quantizing the coefficient data of the prediction error output from the third adder, and a current block output from the inverse quantizer And another inverse transforming means for inversely transforming the coefficient data of the current block and outputting the restored image data of the current block.

Further, an image predictive decoding apparatus according to a thirteenth aspect is an image predictive decoding apparatus provided corresponding to the image predictive encoding apparatus according to the ninth aspect, wherein the image predictive encoding apparatus Extracting means for extracting an indicator bit from the received data received from the block memory, a block memory for storing coefficient data of a reconstructed block, and the block memory based on a prediction block indicated by the indicator bit extracted by the extracting means. Another prediction means for generating and outputting coefficient data of a prediction block with respect to coefficient data of a current block included in the received data, using coefficient data of a previously restored block stored in the received data, Decoding means for entropy decoding the received data and outputting decoded prediction error coefficient data; and An inverse quantization means for inversely quantizing and outputting the coefficient data of the prediction error output, and a coefficient of the prediction error output from the inverse quantization means, A third adding means for restoring and outputting the current coefficient data of the current block by adding the coefficient data to the data, and a coefficient data for the current block output from the third adding means. By inversely transforming the image data of the current block and outputting the restored image data of the current block, and performing motion compensation processing on the image data of the current block output from the another inverse transforming means. And another compensation means for outputting prediction error data for motion compensation, and image data of a current block outputted from the other inverse transformation means By subtracting the prediction error data of a motion compensation output from the further compensation means, and a fifth adding means for outputting the image data of the restored block of the subtraction result.

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, wherein Extracting means for extracting an instruction bit from received data received from the device, a block memory for storing coefficient data of a reconstructed block, and the block based on a prediction block indicated by the instruction bit extracted by the extracting means. Another prediction means for generating and outputting coefficient data of a prediction block with respect to coefficient data of a current block included in the received data, using coefficient data of a previously restored block stored in a memory; , Entropy decoding the received data,
Decoding means for outputting decoded prediction error coefficient data, and adding the prediction block coefficient data output from the prediction means to the prediction error coefficient data output from the decoding means, The coefficient data of the current block at the present time is restored and output, and the third addition means stored in the block memory and the coefficient data of the prediction error output from the third addition means are dequantized and output. Inverse quantization means, another inverse transformation 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, and the other inverse transformation means Compensating means for outputting motion prediction error data by performing motion compensation processing on the image data of the current block output from Subtracting the prediction error data of the motion compensation output from the another compensating means from the image data of the current block output from the other inverse transforming means, and outputting the restored image data of the subtracted block And a fifth adding means for performing the operation.

An image prediction encoding apparatus according to a fifteenth aspect of the present invention provides a 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, Means for converting the image data of the restored block into coefficient data of a predetermined conversion area, a block memory for storing the restored coefficient data of the block, and a coefficient of the previously reconstructed block stored in the block memory. Based on the data, 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, and among the coefficient data of the plurality of prediction blocks formed by the prediction unit,
Determining means for determining and selecting the most efficient coefficient data of the predicted block and the scanning method, outputting the selected prediction block and the indicator indicating the selected scanning method to the image prediction decoding apparatus in the form of instruction bits And the coefficient data of the prediction block selected by the determining means,
By subtracting from the current coefficient data of the current block, the first addition means for outputting coefficient data of the prediction error resulting from the subtraction, and quantizing the prediction error coefficient data output from the first addition means. Quantizing means, and scanning means for executing a scanning process on the coefficient data of the prediction error from the quantization 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 a prediction error after the scanning process output from the scanning means, and transmitting the encoded coefficient data of the prediction error to an image prediction decoding device; and Dequantizing means for dequantizing coefficient data of a prediction error from the means and outputting coefficient data of a reconstructed block; The coefficient data of the prediction block output from the inverse quantization unit is added to the coefficient data of the prediction error output from the inverse quantization means, thereby outputting the restored coefficient data of the block and storing the coefficient data in the block memory. 2 adding means and an inverse transforming means for inversely transforming the coefficient data of the block output from the second adding means to generate image data of the restored block.

The image predictive coding apparatus according to a sixteenth aspect of the present invention provides a sampling means for sampling 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 the plurality of blocks into coefficient data of a predetermined conversion area, quantization means for quantizing the coefficient data of the conversion area from the conversion means, and coefficient data of the restored block. Based on the block memory to be stored and the coefficient data of the previously reconstructed block stored in the block memory, coefficient data of a plurality of prediction blocks is formed from the coefficient data of the block converted by the conversion unit. Predictive means to
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 apparatus in the form of an instruction bit, and subtracting coefficient data of a prediction block selected by the determining means from coefficient data of a current block at the present time, thereby predicting a subtraction result. A first adder for outputting coefficient data of the error, and a scan process performed by the scan method determined by the determiner on the coefficient data of the prediction error from the first adder; A scanning means for outputting coefficient data of the prediction error of the image, and a prediction after the scanning process outputted from the scanning means. Encoding means for entropy-encoding the error coefficient data and transmitting the encoded prediction error coefficient data to the image predictive decoding device; and the prediction error coefficient data from the first adding means, A second adding means for restoring and outputting the quantized coefficient data of the current block by adding the coefficient data of the prediction block outputted from the means, and storing the data in the block memory; Inverse quantization means for inversely quantizing the coefficient data of the current block output from the adding means and outputting the result; and image data of the block restored by inversely transforming the coefficient data of the current block from the inverse quantization means And inverse conversion means for generating Further, an image prediction encoding apparatus according to a seventeenth aspect of the present invention comprises a sampling unit for sampling an input image signal into image data of a plurality of blocks each including a two-dimensional array of pixel values, and image data of the input block. The motion compensation processing is performed on the compensation means for generating and outputting the image data of the prediction error of the motion-compensated block, and from the image data of the block output from the sampling means, First adding means for subtracting the image data of the prediction error of the output block and outputting the image data of the block as a result of the subtraction; and converting the image data of the block output from the first adding means into a predetermined transform. A conversion unit for converting the coefficient data of the area, a block memory for storing the coefficient data of the restored block, A prediction unit for forming coefficient data of a plurality of prediction blocks from coefficient data of a block converted by the conversion unit based on coefficient data of a block reconstructed before stored in a memory; Among the coefficient data of the plurality of prediction blocks formed by, the coefficient data of the most efficient prediction block and the scanning method are determined, selected and output,
Determining means for transmitting an indicator representing the selected prediction block and the scanning method to the image prediction decoding apparatus in the form of an instruction bit; and transmitting coefficient data of the prediction block selected by the determination means to the current block of the current block. A second adding unit that outputs coefficient data of a prediction error resulting from the subtraction by subtracting the coefficient data from the coefficient data; a quantizing unit that quantizes the coefficient data of the prediction error output from the second adding unit; Scanning means for performing a scan process on the coefficient data of the prediction error from the quantization means by the scanning method determined by the determination means, and outputting coefficient data of the prediction error after the scan processing; The entropy encoding is performed on the coefficient data of the prediction error after the scan processing output from the Encoding means for transmitting the data to the image prediction decoding apparatus, inverse quantization means for inversely quantizing the coefficient data of the prediction error from the quantization means, and outputting coefficient data of the restored block, By adding the coefficient data of the prediction block output from the means to the coefficient data of the prediction error output from the inverse quantization means, the restored coefficient data of the block is output and stored in the block memory. Third adding means;
Inverse transform means for generating image data of a restored block by inversely transforming the coefficient data of the block output from the third adding means, and image data of the restored block from the inverse transform means A fourth adding unit that adds the image data of the prediction error of the motion-compensated block output from the compensating unit and outputs the restored image data of the block to the compensating unit.

Still further, an image predictive encoding apparatus according to an eighteenth aspect of the present invention comprises a sampling means for sampling an input image signal into image data of a plurality of blocks including pixel values in a two-dimensional array; By performing motion compensation processing on the image data of (i), the compensation means for generating and outputting the image data of the prediction error of the motion-compensated block, and the image data of the block output from the sampling means, First adding means for subtracting the prediction error image data of the block output from the compensating means and outputting the image data of the block resulting from the subtraction; and calculating the block image data output from the first adding means. Conversion means for converting coefficient data of a predetermined conversion area into coefficient data of the predetermined conversion area, and quantization means for quantizing coefficient data of the conversion area from the conversion means A block memory for storing the coefficient data of the restored block, and a coefficient data of the block converted by the conversion means based on the coefficient data of the previously reconstructed block stored in the block memory. Prediction means for forming coefficient data of a plurality of prediction blocks; and coefficient data of the most efficient prediction block and a scanning method among coefficient data of the plurality of prediction blocks formed by the prediction means are determined, selected and output. Determining means for transmitting an indicator indicating the selected prediction block and the scanning method to the image prediction decoding apparatus in the form of an indication bit; and transmitting coefficient data of the prediction block selected by the determination means at the current time. By subtracting from the coefficient data of the block, the coefficient data of the prediction error resulting from the subtraction is output. A second adding means for performing a scan process on the coefficient data of the prediction error from the second addition means by the scan method determined by the determining means, and calculating the coefficient data of the prediction error after the scan processing; A scanning unit for outputting, and an encoding unit for entropy-encoding the coefficient data of the prediction error after the scan processing output from the scanning unit 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 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. The third adding means stored in the block memory and the coefficient data of the current block output from the third adding means are inverted. Inverse quantization means for quantizing and outputting; inverse transform means for generating image data of a restored block by inversely transforming coefficient data of the current block from the inverse quantization means; and Adding the image data of the prediction error of the motion-compensated block output from the compensating means to the image data of the reconstructed block, and outputting the restored block image data to the compensating means. And an adding means.

An image predictive decoding device according to a nineteenth aspect is an image predictive decoding device provided corresponding to the image predictive encoding device according to the fifteenth aspect, wherein the image predictive decoding device receives the image predictive decoding device from the image predictive encoding device. Extracting means for extracting an instruction bit from the received data, a block memory for storing coefficient data of a reconstructed block, and storing in the block memory based on a prediction block indicated by the instruction bit extracted by the extracting means. Another prediction means for generating and outputting coefficient data of a prediction block with respect to the coefficient data of the current block included in the received data using the coefficient data of the previously restored block,
Decoding means for entropy decoding the received data and outputting decoded prediction error coefficient data; and prediction error coefficient data output from the decoding means, extracted by the extraction means. Based on the scan method indicated by the indicated bit, performs reverse scan processing, and outputs coefficient data of the prediction error after the reverse scan processing, and reverse scan processing that is output from the reverse scan processing. Inverse quantization means for inversely quantizing and outputting the prediction error coefficient data, and adding the prediction block coefficient data output from the another prediction means to the prediction error coefficient data output from the inverse quantization means By doing so, the third addition means for restoring and outputting the coefficient data of the current block at the present time and storing the coefficient data in the block memory is provided. And inverse transform coefficient data of the current block outputted from said third adding means, and a separate inverse conversion means for outputting the image data of the restored current block.

An image prediction decoding apparatus according to a twentieth invention is an image prediction decoding apparatus provided corresponding to the image prediction encoding apparatus according to the sixteenth invention, wherein the image prediction decoding apparatus is Extracting means for extracting an instruction bit from the received data received from the block memory, a block memory for storing coefficient data of a reconstructed block, and the block memory based on a prediction block indicated by the instruction bit extracted by the extracting means. Another prediction means for generating and outputting coefficient data of a prediction block with respect to coefficient data of a current block included in the received data, using coefficient data of a previously restored block stored in the received data, Decoding means for entropy decoding the received data and outputting decoded prediction error coefficient data; and A reverse scan process is performed on the output prediction error coefficient data based on the scan method indicated by the instruction bit extracted by the extraction unit, and the prediction error coefficient data after the reverse scan process is output. The inverse scan means and the coefficient data of the prediction block output from the prediction means are added to the coefficient data of the prediction error output from the inverse scan means to restore the coefficient data of the current block at the present time. A third adding means for outputting and storing in the block memory, a dequantizing means for dequantizing and outputting the coefficient data of the prediction error output from the third adding means, Another inverse transform that inversely transforms the coefficient data of the current block output from and outputs the restored image data of the current block And a stage.

Further, an image predictive decoding apparatus according to a twenty-first aspect is an image predictive decoding apparatus provided corresponding to the image predictive encoding apparatus according to the seventeenth aspect, wherein Extracting means for extracting an indicator bit from the received data received from the block memory, a block memory for storing coefficient data of a reconstructed block, and the block memory based on a prediction block indicated by the indicator bit extracted by the extracting means. Another prediction means for generating and outputting coefficient data of a prediction block with respect to coefficient data of a current block included in the received data, using coefficient data of a previously restored block stored in the received data, Decoding means for entropy decoding the received data and outputting decoded prediction error coefficient data; and decoding means A reverse scan process is performed on the coefficient data of the prediction error output from the base station based on the scan method indicated by the instruction bit extracted by the extraction unit, and the coefficient data of the prediction error after the reverse scan process is obtained. Inverse scanning means for outputting, inverse quantization means for inversely quantizing the coefficient data of the prediction error after the inverse scanning process outputted from the inverse scanning means and outputting the data, and a prediction block outputted from the another prediction means. Third adding means for restoring and outputting the coefficient data of the current block at the present time by adding the coefficient data to the coefficient data of the prediction error output from the inverse quantization means, and storing the data in the block memory And inversely transform the coefficient data of the current block output from the third adding means,
Another inverse transform unit that outputs the restored image data of the current block, and a motion compensation process is performed on the image data of the current block output from the another inverse transform unit, thereby obtaining a prediction error of motion compensation. Another compensating means for outputting data, and subtracting the prediction error data of the motion compensation output from the another compensating means from the image data of the current block output from the other inverse transforming means,
A fifth adding unit that outputs image data of the block in which the subtraction result is restored. 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, wherein the image prediction decoding apparatus receives the image prediction decoding apparatus from the image prediction encoding apparatus. Extracting means for extracting an instruction bit from the received data, a block memory for storing coefficient data of the reconstructed block, and storing in the block memory based on a prediction block indicated by the instruction bit extracted by the extracting means. Using the previously restored block coefficient data
Another prediction means for generating and outputting coefficient data of a prediction block with respect to coefficient data of a current block included in the reception data at the present time, and entropy decoding of the reception data to obtain a coefficient of a decoded prediction error Decoding means for outputting data; and performing inverse scanning on the coefficient data of the prediction error output from the decoding means, based on a scanning method indicated by the instruction bits extracted by the extracting means. Inverse scanning means for outputting coefficient data of a prediction error after inverse scanning, and coefficient data of a prediction block output from the prediction means,
A third adding means for restoring and outputting the current coefficient data of the current block by adding the coefficient data to the prediction error output from the inverse scanning means and storing the coefficient data in the block memory; A dequantizing means for dequantizing and outputting the coefficient data of the prediction error output from the adding means, and an inverse transform of the coefficient data of the current block output from the dequantizing means to obtain a restored current block. Another inverse transforming means for outputting the image data of the current block, and performing motion compensation processing on the image data of the current block outputted from the other inverse transforming means, thereby outputting prediction error data for motion compensation. From the image data of the current block output from the another inverse transforming means, and the motion compensation output from the other compensating means. Fifth prediction error data by subtracting the outputs the image data of the restored block of the subtraction result
And an adding means.

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

Further, the picture predictive decoding method according to the twenty-fourth aspect of the present invention includes steps in which each unit in the picture predictive decoding apparatus is replaced with each step.

A recording medium according to a twenty-fifth aspect of the present invention is a recording medium storing a program including each step in the above-described image predictive encoding method.

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

[0057]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments according to the present invention will be described below 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 showing a configuration of an image predictive coding apparatus according to a first embodiment of the present invention.

In FIG. 1, reference numeral 101 denotes an input terminal;
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 signal generator.

Hereinafter, the configuration and operation of the image predictive coding apparatus 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. Show. 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 optimal predicted small area image data.

The adder 102 subtracts the corresponding pixel value of the optimal predicted small area from the prediction signal generator 112 from the pixel value of the input image data in the small area to be processed, and obtains the difference small area resulting from the subtraction. , And outputs the image data 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 in 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 the decoder 107, where the decoder 1
07 includes an inverse quantizer 108 and an inverse DCT transformer 109, and restores the input small area image data to the expanded difference small area image data. 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). .) 10
9, the image signal is converted into an image signal in the spatial domain. The image data of the expanded difference small area obtained in this manner is added to the adder 110.
The adder 110 adds the optimal prediction image signal output from the prediction signal generator 112 via the lines 121 and 122 to the image data of the expanded difference small area, Is generated, and a reproduction pixel value for generating an intra-screen prediction image signal is stored in the line memory 111 from the image data of the reproduction small area. 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 area to be processed as the pixel value of the image data of the intra prediction small area.

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, b _2,
..., it is a b _6, b _7. In FIG. 3, assuming that a triangle 301 is a small area to be processed, the pixel values of adjacent reproduced image data are g ₀ , g ₁ ,..., G ₄ , f ₀ , f ₁ , f ₂ ,.
f ₇ and 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. Prediction signal generator 11
2 accesses the line memory 111 and reads 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 show first and second predictive signal generators used in the image predictive coding apparatus of FIG. 1, respectively.
FIG. 3 is a block diagram showing a configuration of the example.

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

[0068] In FIG. 5, the pixel values b ₀ adjacent in the vertical direction with respect to the objective small region to be _{processed, b 1, b 2, ...} , b 6, b
₇ is input from the line memory 111 to the prediction signal generator 112, and the generator 402 in the prediction signal generator 112 repeatedly outputs the pixels in the vertical direction, for example, eight times to output the image data of the intra-screen prediction small area. 404 is generated.
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 and vertical directions, the image data of the 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 picture prediction encoding apparatus of FIG.

In FIG. 6, image data 403 (see FIG. 5) of an intra-screen predicted small area generated by generator 401 and image data 404 of an intra-screen predicted small area generated by generator 402 are added. Input to the adder 500, the adder 500 averages these two pieces of image data by dividing the sum of the two pieces of input image data by two. In this way, the adjacent reproduced pixels by the generators 401 and 402 are repeatedly output,
Since only the averaging operation is performed by 00, 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 picture prediction encoding apparatus of FIG.

In FIG. 7, the pixel values a ₀ , a ₁ , and
a ₂ ,..., a ₆ , and a ₇ are input from the line memory 111 to the generator 401, and the generator 401 repeatedly outputs pixels in the horizontal direction to output image data of the first intra prediction small area. Generate On the other hand, pixel values b ₀ , b ₁ , b ₂ ,... Vertically adjacent to the small region to be processed
b ₆ and b ₇ are input to the generator 402 from the line memory 111, and the generator 402 generates image data of the second intra prediction small area by repeatedly outputting pixels in the vertical direction. The image data of the first predicted small area in the screen and the image data of the second predicted small area in the screen are added to the adder 50.
The image data of the third predicted small area in the screen is generated by averaging these two pieces of image data.

On the other hand, the image data of the small area to be processed is
Error calculators 601, 602, 60 via line 616
3 is input. 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. 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 an absolute value of an error between these two 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 the value of the comparator 6 is calculated.
04.

The comparator 604 compares the three input absolute errors with each other to determine the one with the smallest absolute error, and outputs the corresponding image data of the intra prediction small area to the line 121. The switch 605 is controlled. At the same time, the comparator 604 outputs an identifier for identifying the image data of the first, second and third predicted small areas in the screen to the receiving or reproducing apparatus via the line 615. With this identifier, the image data of the intra prediction small area on the receiving side or the reproducing side is uniquely determined. By using the image data of the intra prediction small area having the smallest error in this way, it is possible to suppress the difference signal at the time of encoding, and it is possible 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. It is attached. 8 is different from the image prediction encoding apparatus in 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 coding apparatus shown 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 outputs the image data of the small area to be processed. After subtracting the data from the optimal prediction small area image data input via the line 121 from the optimal mode selector 703, the subtracted image data is output to the encoder 103. The encoder 103 compression-encodes the input subtracted image data and outputs it through 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 the conversion, 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, while the pixels of the reproduced image are stored. All values are stored in the frame memory 702.

When image data of the next image is input via the input terminal 101, the motion detector 700 outputs the image data of the small area to be processed and the reproduced image data stored in the frame memory 702. Is input and the motion detector 7
00 detects motion of an image by a method such as block matching and outputs a motion vector via a line 705. The outputted motion vector is sent to the motion compensator 701 at the same time as, for example, variable-length coding, storing or transmitting (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 generated image data to the optimal mode selector 703. In the motion detection processing and the motion compensation processing, there are forward prediction, backward prediction, and bidirectional prediction, and these methods are described in, for example, US Pat.
No. 04.

On the other hand, as in the first embodiment, the prediction signal generator 112 generates the image data of the intra-screen prediction small area and outputs it to the optimal mode selector 703, and at the same time, generates the image data of the small area to be processed. The data is output to the optimal mode selector 703. The optimum mode selector 703 determines the most error (for example, the sum of the absolute values of the differences for each pixel) in the image data of the small region to be processed from the image data of the intra prediction small region and the image data of the temporal prediction small region. ) Is selected, and the selected image data is output to the adder 102 as the image data of the optimal prediction small area. An identifier indicating which predicted small area image data is selected is output to the receiving side or the reproducing side via a line 709 and transmitted.

As described above, by introducing intra prediction into the image data of the inter-frame motion compensation coding, it is not necessary to transmit a motion vector between frames, so that 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 with 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 of the significant object and its shape, it is possible to reproduce and display the object. When the prediction signal generator 112 generates image data of an intra prediction small area for such an input image, insignificant pixel values cannot be used.

FIGS. 9 to 11 show schematic diagrams of an input image having significant 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 expanded and reproduced again, 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 composed 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 be the pixel values of the intra-screen prediction small area of the small area 802 to be processed.

In FIG. 10, the shape curve 804
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 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 area 810 to be processed,
a ₅ , a ₆ , a ₇ , b ₄ , b ₅ , b ₆ , and b ₇ are significant pixels, and only these pixel values are repeatedly output. When two pixel values overlap each other, A value obtained by averaging the pixel values is set 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 area 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,
Value of a pixel z ₁₄ is the average value of a ₅ and b _4. in this way,
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 performed similarly.

As another embodiment, a significant pixel value
The average value using only
The pixel value of the small area may be used. Specifically, in FIG.
Pixel b_Four, B_Five, B₆, B₇Calculate the average of the calculated
The average value is set as the pixel value of the intra prediction small area. In FIG.
Is the pixel a_Four, A_Five, A₆, A₇Calculate the average of the
The obtained average value is used as the pixel value of the intra prediction small area. FIG.
Then, pixel a_Five, A₆, A ₇, B_Four, B_Five, B₆, B₇The average of
The value is calculated and used as the pixel value of the intra prediction small area.

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

In FIG. 12, reference numeral 901 denotes an input terminal;
2 is a data analyzer, 903 is a decoder, 906 is an adder, 907 is an output terminal, 908 is a controller, 909
Denotes a motion compensator, 910 denotes a prediction signal generator, 911 denotes a line memory, and 912 denotes a frame memory.

The configuration and operation of the picture prediction decoding apparatus shown in FIG. 12 will be described below. In FIG. 12, the compression-encoded image data is input to a data analyzer 902,
The data analyzer 902 analyzes the input image data, outputs the compressed differential small area image data to the decoder 903 via the line 915, and outputs the control signal to the line 9
26 to the controller 908, and
The above-described motion vector (only when it exists) is output to the motion compensator 909. The decoder 903 includes the inverse quantizer 90
4 and an inverse DCT transformer 905, and expands the compressed image data of the small difference area to restore the image data of the expanded small difference area.

In this 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 inverse DCT.
The image data is converted into image data in the spatial domain by the converter 905. The converted image data of the expanded difference small area is added to the adder 90.
6 is input to the adder 906, and the image data of the input decompressed difference area is input from the motion compensator 923 or the prediction signal generator 922 through the switch 913 and the line 924. To generate image data of a reproduction small area as a result of the addition. Adder 90
6 outputs the reproduced image data to an output terminal 907 via a line 917 and simultaneously outputs the frame memory 91
2 is stored. Further, the pixel value of the image data used for generating the image of the intra prediction small area is stored in the line memory 911.

The image data of the optimal prediction small area is supplied to the controller 90 based on a control signal from the data analyzer 902.
8, the 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 the controller 908
In response to the control signal from, the prediction signal generator 910 accesses the line memory 911 and outputs the adjacent reproduced pixel values as the pixel values of the intra-screen 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 controller 908 selects the image data of the temporal prediction small area, the switch 913 changes the line 924 to the line 923.
, And in response to a control signal from the controller 908, the motion compensator 909 performs motion compensation on the image data from the frame memory 912 based on the motion vector sent from the data analyzer 902 via line 925. By executing the processing, the image data of the temporal prediction small area is generated and output to the adder 906 via the switch 913 and the line 924.

<Fourth Embodiment> FIG. 13 is a block diagram showing a configuration of an image prediction decoding apparatus according to a fourth embodiment of the present invention. The same reference numerals are given. 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 the compression-encoded shape data. The data analyzer 902 extracts this shape data and outputs it to the shape decoder 990. In response to this, 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 receiving side or the reproducing side. The prediction signal generator 910 includes:
Based on the reproduced shape signal, as described with reference to FIGS. 9 to 11, the image data of the intra prediction small area is generated. In this manner, 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. Without the line memory 911, the pixels for generating the 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 areas, it is necessary to write and read the frame memory at high speed. By providing a dedicated line memory or buffer, it becomes possible to generate the 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 merely used as the pixel value of the intra prediction signal. In addition, it is possible to easily generate a high-precision prediction signal with a small amount of calculation compared with the related art, 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 the reproduced pixel value used for generating the intra prediction signal, the pixel value can be accessed at high speed, and the intra prediction signal can be transmitted at high speed. Can be generated.

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

The present inventor considered the problems of the prior art,
The image coding efficiency is 2 between two images or within one image.
Not only between the interiors of one block, but also
It has been found that removing the redundancy between two blocks further improves the image coding efficiency.

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

This type of redundancy that exists in the DCT transform domain beyond the block can be eliminated or significantly reduced by adaptive intra prediction (intra-frame prediction) from the previous block. And the next VLC
In the entropy coding process, higher coding efficiency can be achieved by entropy having 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 method for appropriately predicting DCT transform coefficients from other blocks. This scheme eliminates 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 in one of the adjacent blocks previously decoded
Are predicted. 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 may be shifted upward, to the left, diagonally to the left, upward, diagonally to the right, and upward to the currently encoded DCT transform block. 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 notified of which adjacent block has predicted the current block.

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 uses D
This is because the same value or the same distribution of the CT conversion coefficient tends to be given.

Normally, first, DCT transform processing based on blocks is performed on input image data, which are intra frames or temporarily predicted frames. 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, ie, upper left block B
1, upper block B2, upper right block B3, and left block 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. Also all D
It can be obtained by partially subtracting the DCT transform coefficient instead of the CT transform coefficient.

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 together with an instruction bit that informs the picture prediction decoding apparatus of a prediction decision.

In the picture prediction decoding apparatus, 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 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 provides spatial redundancy normally removed by transforms such as DCT, redundancy removed between frames by motion detection and compensation, and quantized transform coefficients in blocks. And an image coding apparatus capable of reducing other types of redundancy existing in the DCT transform domain beyond adjacent blocks, in addition to the statistical redundancy removed by entropy coding. is there.

FIG. 1 shows a conventional image predictive coding apparatus.
As can be seen from FIG. 4, conventional image coding (eg, MP
A commonly used image predictive coding device is a block sampling unit 1001, D
It comprises a CT transform unit 1004, a quantizer 1005 and an entropy encoder 1006.

In intra-frame coding (intra-frame coding), first, block sampling processing is performed on an input image signal. Then DC directly
T conversion processing is performed. Subsequently, a quantization process and an entropy coding process are performed. On the other hand, in inter-frame coding (predictive frame coding),
After the block sampling processing, the motion detection unit 1
002 and the processing of the motion compensation unit 1003 are executed, and further, the DCT transform processing is executed. Further, a quantization process and an entropy encoding process are performed.

Here, the entropy coding unit 10
At 06, the quantized value is entropy coded and code data is output. Entropy coding is a method that assigns a short codeword to frequently occurring values and a long codeword to values that rarely occur, thereby encoding the data so that it approaches the average information entropy. Is a method that greatly reduces 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 are concentrated around 0, so that entropy coding is effective. Also,
For the AC coefficient, for example, a zigzag scan is performed and 2
Converts dimensional data into one-dimensional data. Furthermore, since many AC coefficients including high-frequency components generate many 0s, entropy coding is performed using a set of AC coefficient values having values other than 0 and the number of 0s before them (run length) as a set.

The rate controller 1007 feeds back the bits used for the previously encoded block, controls the processing of the 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 performed in units 1008 and 100
9 is performed. The image data decoded by the local decoder is stored in a local decoded frame memory 1010.
And used for motion detection processing. 1011
Is a reference frame memory for storing a previous original frame for motion detection. Then, 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 shows an adaptive DC for intra prediction.
It is a schematic diagram of an image for explaining a T conversion area.

FIG. 15 shows that, in the DCT transform area, four 8 × 8 DCT transform blocks constitute a macro block. Here, B0 indicates the current block having the 8 × 8 DCT transform coefficient. B2 indicates the 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. FIG. 15 shows that a block having DCT transform coefficients can be predicted from a plurality of decoded adjacent blocks having 8 × 8 DCT transform coefficients.
Understand from.

It should be noted that the block from which the current block is predicted is always different. Therefore, a decision based on the minimum bit usage rule is executed, and the decision is adaptively given to different blocks on the image predictive 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, the amount of bits 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 showing a configuration of an image predictive coding apparatus according to a fifth embodiment of the present invention. The image prediction encoding apparatus in FIG.
The DCT transform region prediction processing is characterized in that it is performed after the quantization processing.

In FIG. 16, first, block sampling is performed by the block sampling unit 1012 on the input image signal. Then, in the intra-frame encoding, the sampled block image data is not subjected to the processing of the adder 1013, and
DCT transform unit 1014 through adder 1013
Is input to 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 outputs the subtracted image data to the DCT transform unit 1014. And D
After the CT transform processing is performed in the unit 1014, the quantization processing is performed in the unit 1015.

The DCT transform area prediction processing is performed in the unit 101
Performed at 7, 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, for the predicted DCT transform block, the entropy VL
The C encoding process is performed, and the encoded bits are written to a bit stream.

The adder 1019 restores the current DCT transform block by adding an adjacent block before being used for prediction to the prediction block. Next, for the reconstructed DCT transform block, inverse quantization and inverse DCT
1 and 1022. 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 showing a configuration of an image predictive coding apparatus according to a sixth embodiment of the present invention. The image prediction encoding apparatus in FIG.
It is characterized in that a DCT transform region prediction process is performed before the quantization process. The unit 1026 performs block sampling processing on the input image signal. Next, the adder 1027 performs a 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 to obtain the entropy VLC.
Encoding unit 1034 and inverse quantization unit 1033
Is output to

The block memory 1032 includes the unit 10
The image data of the previous block is stored for the DCT transform area prediction processing of No. 31. DCT conversion unit 102
The image data of the current DCT transform block output from 8 is subtracted by the adder 1029 from the previous DCT transform block selected by the DCT transform area prediction unit 1031 according to the rule of using the minimum bit. The image data of the DCT transform block as a result of the subtraction is quantized by the quantization unit 1030, and then the inverse quantization unit 1
033 and entropy VLC encoding unit 1034
Is output to The inverse quantization unit 1033 restores the input image data of the quantized DCT transform block by inverse quantization, and outputs the restored image data to the adder 1035. The adder 1035 converts the restored image data of the DCT transform block into a DCT transform area prediction unit 1031.
, The image data of the block before the DCT transform block is added, and the image data of the block before the sum is stored in the block memory 1032 and output 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. I do. Adder 1
Reference numeral 037 denotes a motion detection and compensation unit 1 for the restored image data output from the inverse DCT transform unit 1036.
025, and adds the image data of the frame before output from the frame memory 1038.
After being temporarily stored in the motion detection and compensation unit 10
25.

<B1. General description of mode determination> FIG.
8 is a DCT transform area prediction circuit 10 shown in FIGS.
It is a block diagram which shows the structure of 17, 1031.

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 reads the previous adjacent D stored in the block memory 1040.
By subtracting the image data of the current block input from the CT transform block, the following four types of image data of the predictive DCT transform block are obtained. (A) No-Pred block indicated by 1042,
(B) Up-Pred block indicated by 1043,
(C) Left-Pred block indicated by 1044, and (d) Other-Pred block indicated by 1045.

Here, the above four types of blocks are shown using two bits. That is, for example, "00" is No-
Pred block, “01” indicates Up-Pred block, “10” indicates Left-Pred,
“11” indicates the 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 the image data of the prediction block obtained when the block used for prediction is the DCT transform block B2 that is adjacent above. Le
The ft-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. Other-
The Pred block indicates image data of the prediction block when the prediction is performed only on the DC coefficient. Other
In the case of -Pred, there are two types of prediction methods. That is, Up-DC-Pred (1046) indicates image data of a prediction block obtained when prediction is performed only on the DC coefficient based on the DCT transform block B2 adjacent above. Left-DC-Pred
(1047) is the DCT transform block B4 adjacent to the left side
5 shows image data of a prediction block obtained when prediction is performed only on the DC coefficient based on. For these two cases, another bit is needed for the indication. For example, “0” indicates Up-DC-Pred (104
6), and “1” indicates Left-DC-Pred (10
47).

Although the prediction based on the blocks B1 and B3 adjacent in the oblique direction is possible, the prediction result is not as good as the prediction based on the upper and left blocks.
Not used in the present embodiment.

All the predicted blocks are checked and checked by performing the actual entropy coding process by the unit 1048. The bits used for the different predicted blocks are unit 1
049. Finally, unit 1050
Determines the predicted DCT transform block based on the least bit usage rule, and
Output the T conversion block. That is, a 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.

Referring to FIG. 19, the DC / A
A subset of the C-predicted image data is shown for actual use. The current block 1101 is an upper left 8 × 8 block of the current macro block,
The current block 1102 is an upper right 8 × 8 block of the current macro block. 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. By the same procedure, the current block 1
102 is predicted from the block D above and the current block 1 on the left.

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

(A) Mode 0: DC prediction only

[0138]

E ₀ (0,0) = C (0,0) − (A (0,0)
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 from upper block
/ AC prediction

[0140]

## EQU2 ## E ₁ (0, v) = C (0, v) −A (0, v)
v), v = 0,..., 7, E ₁ (u, v) = C (u, v), u = 1,.

(C) Mode 2: DC from left block
/ AC prediction

## EQU3 ## E ₂ (u, 0) = C (u, 0) -B (u,
0), u = 0,..., 7, E ₂ (u, v) = C (u, v), u = 0,.

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. Will be

[0143]

(Equation 4) 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 the differences in the applications targeting different coding bit rates. The modes are encoded using the variable length codes in Table 1 below.

[0145]

[Table 1]

In the case where DC / AC prediction is performed after quantization, the preceding horizontal neighboring block or vertical neighboring block usually uses a different quantization step, so that accurate DC / AC prediction is performed. Requires several types of weighting factors to scale the quantized DCT transform coefficients.

Let QacA be the quantized DCT transform coefficient of block A (see FIG. 19), and let 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 to be used for quantization of current block C. , And thus the scaling equation is:

[0148]

## EQU5 ## Q'acA = (QacA × QstepA) / Q
stepC

## EQU6 ## Q'acB = (QacB × QstepB) / Q
stepC

Here, Q'acA is the value of D from block A.
It is a CT conversion coefficient and is used for prediction of the top row of the 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 showing a configuration of an image prediction decoding apparatus according to a seventh embodiment of the present invention.

In FIG. 20, the bit stream from the image predictive coding apparatus is input to an entropy VLD decoding unit 1051 and is subjected to variable length decoding. The decoded image data is subjected to DCT by an adder 1052.
Previous adjacent DC from transform domain prediction unit 1053
By adding to the image data of the T conversion block, D
The image data of the CT conversion block is restored. Which block is the DCT transform block adjacent before is
It is signaled by indication bits taken from the bitstream and used in unit 1053 for prediction. 1054 is an adjacent DC used for prediction.
This is a block memory for storing the T conversion block. 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 receives the input DCT
By performing an inverse DCT transform process on the transform block, image data of DCT transform coefficients restored is generated and output to the adder 1056. An adder 1056 adds the reconstructed 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 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 the inverse restoration processing corresponding to the processing of the block sampling units 1012 and 1026 in FIGS. You.

Further, reference numeral 1059 denotes an inverse quantization unit. When the DCT transform area prediction processing is performed before the quantization processing as shown in FIG.
20 is inserted at the position of 1059a in FIG. 20, while when the DCT transform area prediction processing is performed after the quantization processing as shown in FIG. 16, the inverse quantization unit 1059 is placed at the position of 1059b in FIG. Inserted.

FIG. 21 is a flowchart showing a decoding method of DC / AC prediction in the picture 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, and in step 1060, the flag of the instruction bit is checked.
If it is "0", in step 1061, a DC value is calculated from the average value of the image data of the upper block and the left block, and the flow advances to step 1063. If NO in step 1060, the process proceeds to step 1062,
If the instruction flag checked in step 2 is "10", the image data of the left column of the left block is extracted in step 1063, and the process proceeds to step 1065. If NO in step 1062, the process proceeds to step 1064, where step 106
If the display flag checked in 4 is “11”, the image data of the top row of the upper block is extracted in step 1065, and the process proceeds to step 1066. Finally, in step 1066, steps 1061, 1063, or 10
The DCT transform coefficients obtained or extracted at 65 are added to the corresponding DCT transform coefficients of the current block.

Further, a modified example of this embodiment group will be described below.

(A) In the block sampling units 1012 and 1026, the pixels in 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 Block consists of even-numbered pixels in odd-numbered rows, block 3 consists of odd-field pixels in even-numbered rows, and block 4 consists of even-numbered pixels in even-numbered rows. As described above, an interleaving process for alternately inserting pixels 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 transforms in the block are selected. A coefficient may be selected. (C) the prediction block is selected from a block stored in the block memory and previously restored, the block being positioned adjacent to the current coded block, and a predetermined subset is selected; It may be selected as the transform coefficient of the block.

(D) The prediction block is a block stored in the block memory and previously restored,
Selected from the blocks located adjacent and above and to the left of the current block being coded, only the transform coefficients in the top row of the block and the leftmost column of the block are used, and the remaining transform coefficients are zero. May be set. (E) The prediction block is selected from blocks previously stored in the block memory and previously restored and located in the vicinity of the coded 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 previously restored and located in the vicinity of the encoded current block. A conversion operation may be performed.

(G) The prediction block is a block stored in the block memory and previously restored,
Weighted averaging of a plurality of blocks located near the encoded current block may be performed. (H) When restoring the original image data by forming a two-dimensional array of pixels from a plurality of groups of four interleaved blocks based on the decoded image data, the odd-numbered rows All the odd-numbered pixels are the first
, The even-numbered pixels in the odd-numbered rows are obtained from the second block, the odd-numbered pixels in the even-numbered rows are obtained from the third block, and the even-numbered pixels in the even-numbered rows are obtained. May perform deinterleaving on the decoded image data as determined from the fourth block.

As described above, according to the present embodiment group according to the present invention, the D
It is very effective to remove or reduce the redundancy of the CT transform domain, so that the number of bits used can be reduced, and 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% bits can be saved for higher bit rate coding and 20% for lower bit rate coding.
% Bits can be saved. Also, for example, Akiyo, Mother, and Dauter
For example, about 10% of bits can be saved with respect to other QCIF sequences such as test sequences such as ghter). In addition, more bit savings are possible for CIF and CCIR sequences.

As described above, according to the second embodiment of the present invention, it is possible to provide a new image predictive coding device and a new image predictive decoding device which 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
Image coding efficiency is further improved by reducing redundancy between blocks in an image, as well as between two images or within a block within one image, and by optimizing the scan pattern of the blocks. I thought about improving the redundancy.

It has been found that the DCT transform coefficients in adjacent blocks, even 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 blocks can be eliminated or reduced by adaptive prediction of previous blocks. This is V
LC entropy coding results in 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 significant DCT transform coefficients being concentrated in the leftmost column and topmost transform block. Therefore, the embodiment according to the present invention, based on the prediction mode,
By adapting the scan, the above-mentioned problems in coefficient scanning can be solved.

Embodiments according to the present invention provide a method for adaptively predicting the DCT transform coefficients of the current block from other blocks, and 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.

The embodiment according to the present invention provides a method for estimating the DCT transform coefficient of the current current block. Since the DCT transform tends to give the same value, or the same distribution of DCT transform coefficients, to the same block of image data, 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 based on a normal block is performed on the input image data. Conversion processing is performed. After the DCT transform coefficients of the current block have been obtained, 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
If the prediction is made before the quantization process, it is quantized.
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 apparatus decodes a predicted block using the used prediction mode and 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 is the D in the previously decoded neighboring block, as indicated by the prediction mode.
It can be obtained by adding the CT transform coefficient to the current DCT transform coefficient. 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 DCT transform coefficients reconstructed for each block to obtain a decoded image.

The embodiment according to the present invention provides an image predictive encoding apparatus and an image predictive decoding apparatus for reducing the redundancy existing in the DCT domain beyond adjacent blocks.

<Eighth Embodiment> FIG. 24 is a block diagram showing a configuration of an image predictive coding apparatus according to an eighth embodiment of the present invention. The image prediction encoding apparatus in FIG.
As compared with the conventional image predictive coding apparatus of FIG.
(A) Adder 2035, (b) H / V / Z scan unit 2036, (c) Adder 2038, (d) Block memory 2039, and (e) DCT transform domain prediction unit 2040 having quantization scaling. It is characterized by that.

In the intra-frame coding (intra-frame coding), after the input image signal is subjected to the block sampling processing in the unit 2031, the DCT conversion processing is directly performed in the unit 2033. Next, in a unit 2034, a quantization process is performed on the DCT transform coefficient 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 outputs the image data after the block sampling processing from the motion detection and compensation unit 2045. By subtracting the output image data, prediction error data is obtained. Next, the prediction error data is added to the adder 20 via a DCT transform unit 2033 for performing a DCT transform process and a quantization unit 2034 for performing a quantize process.
35. The DCT transform coefficient is calculated in the unit 204
The DCT transform coefficients predicted by the DCT transform domain processing of 0 are input to the adder 2035. The adder 2035 subtracts the DCT transform coefficient predicted from the DCT transform region 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 adapts to the input DCT transform coefficients, depending on the selected prediction mode,
A horizontal scan, a vertical scan or a zigzag scan is executed, and the DCT transform coefficients after the scan processing are output to the entropy VLC encoding unit 2037. Then
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. DCT transform coefficient data is obtained. The quantized DCT transform coefficient data is stored in the block memory 2039 and the inverse quantization unit 20.
It is output to 41.

In the local decoder provided in the image predictive coding apparatus, the restored DCT transform coefficient data from the adder 2038 stores the data of one block for performing the next prediction.
After that, the data is temporarily output to the DCT transform domain prediction unit 2040. The inverse quantization unit 2041 is
Inverse quantizing the input quantized DCT transform coefficient
Output to the T-transform unit 2042, and then the inverse DCT transform unit 2042 performs an inverse DCT transform process on the input restored DCT transform coefficient to restore the image data of the current block to the adder 2043. Output.

In the inter-frame encoding, an adder 204 is used to generate locally decoded image data.
3 adds the image data motion detected and compensated by the motion detection and compensation unit 2045 and the restored image data from the inverse DCT transform unit 2042,
The locally decoded image data is obtained and 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 showing a configuration of an image prediction decoding apparatus according to the eighth embodiment of the present invention. The image prediction decoding apparatus of FIG. 25 is different from the conventional image prediction decoding apparatus of FIG. 23 in that (a) an H / V / Z scan unit 2052, (b) an adder 2053,
(C) a DCT transform area prediction unit 2055; and (d) a block memory 2054.

In FIG. 25, the bit stream from the image prediction coding apparatus is
1 is decoded. The decrypted data is H /
It is input to the 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 the adder 2053 and the adder 2
053 obtains decoded DCT transform coefficient data by adding the data after the inverse scan processing and the prediction error data from the DCT transform prediction unit 2055, and outputs this to the inverse quantization unit 2056. At the same time, it is stored in the block memory 2054. The inverse quantization unit 2056 then calculates the input encoded D
DC that is inversely quantized by inversely quantizing CT transform coefficient data
After obtaining the T-transform coefficient data, the inverse DCT transform unit 205
7 is output. The inverse DCT transform unit 2057 performs an inverse DCT transform process on the input DCT transform coefficient data to restore the original image data, and
8 is output. In the interframe coding, the adder 2
058 adds the image data from the inverse DCT transform unit 2057 to the prediction error data from the motion detection and compensation unit 2060 to obtain locally decoded image data, and outputs it to an external device; It is 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 prior to the prediction process. In a modification, 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 the macroblock and block structures 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 composed of a block A (u, v) adjacent to the upper side and a block B adjacent to the left.
(U, v). Next, the embodiment of the present invention will be described in more detail.

<C1. Coefficient number used for prediction> coefficient number 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 fixed length codes and FLC for the flag AC_Coeff. Here, FLC (Fixed
LengthCoding (fixed length coding) is a lossless coding that assigns a fixed length codeword to represent all possible events.

[0188]

[Table 2]

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 such 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 the prediction data. This definition is defined in the next section C3. Is given using the equation at.

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

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

[0194]

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”)

[0196]

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 block above the processing block (abbreviated as “upper DC / AC mode”)

[0198]

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”)

[0200]

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 above, the efficiency of intra-frame encoding can be further improved by employing a coefficient scan.

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. Determine explicit mode> explicit (ex
In the determination of the plicit) mode, the prediction mode is determined in the image predictive coding apparatus, and the determination information is obtained from the image predictive coding apparatus using some coded bit information in the bit stream. It is sent explicitly to the decoding device.

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

In FIG. 30, the DC of the current block is
The T-transform coefficient data is input to the unit 2062. The unit 2062 performs the DCT transform prediction process by subtracting the input DCT transform coefficient data from the DCT transform coefficient data of the adjacent block from the block memory 2061. Be executed. Unit 20
62, section C3. In the four modes described in
The T conversion prediction processing is performed. Next, in the H / V / Z scan unit 2063, a coefficient scan process is executed. Here, as shown in FIG. The corresponding scan processing described in (1) 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 executed. 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.

[0206]

[Table 3]

<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
D of the decoded block adjacent to the current block
On the basis of the C coefficient value, the direction regarding the determination of the prediction mode is determined. 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
This is a block above the current block C being predicted.
Block C is a block located on the left side of current block C. Block C ′ is the current block C
Is a block between diagonally located blocks A and B.

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 with the absolute value of the non-prediction coefficients to determine which is smaller. This instruction to the image prediction decoding device includes:
One bit is used. 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

(B (0,0) −C ′ (0,0) <C ′
(0,0) -A (0,0)),

E (0,0) = C (0,0) −A (0,0), and (a1)

[0212]

(Equation 13)

At the time,

[0214]

E (0, v) = C (0, v) -A (0, v)
・ Q _A / Q _C , v = 1, ..., 7,

(A2) If the above equation 13 does not hold,

## EQU15 ## E (0, v) = C (0, v).

(A2) If the above equation (11) does not hold,

E (0,0) = C (0,0) -B (0,0), and if (b1)

[0219]

[Equation 17]

At the time,

[0219]

E (u, 0) = C (u, 0) -B (u, 0)
・ Q _B / Q _C , v = 1, ..., 7,

(B2) If Equation 17 is not satisfied,

E (u, 0) = C (u, 0)

Further, for all other coefficients,

E (u, v) = C (u, v)

[0222]

[Table 4]

In the eighth embodiment described above, the DCT transform coefficient prediction processing is performed on the quantized transform coefficient data by the unit 2040. However, the present invention is not limited to this, and the sixth embodiment of FIG. Similar to the embodiment, the processing 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 to and inserted into the inverse scan unit 2052 and the adder 2053.

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

(A) Block sampling unit 20
31, 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 even-numbered pixels in odd-numbered rows in the second block. The third block comprises an interleaving process of alternately interposing pixels such that the third block is composed of odd-numbered pixels in even-numbered rows and the fourth block is composed 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 restored, the blocks being located adjacent to the current block being coded, and all the coefficients in the block are selected. Data may be selected. (C) the prediction block is selected from a block stored in the block memory and previously restored, the block being positioned adjacent to the current coded block, and a predetermined subset is selected; It may be selected as coefficient data of a block.

(D) The prediction block is a block stored in the block memory and previously restored,
Selected from blocks located adjacent and above and to the left of the current block being coded, only the coefficient data in the top row of the block and the leftmost column of the block are used, and the remaining coefficient data is zero. May be set. (E) the prediction block is stored in the block memory and selected from previously restored blocks according to the criteria described above, and includes one or more coefficient data from the top row or leftmost column of the block; The use of only the subset may be determined by communication between the image prediction encoding device and the image prediction decoding device. (F) The prediction block is stored in the block memory and selected from previously restored blocks according to the criteria described above and includes one or more coefficient data from the top row or the leftmost column of the block. The image prediction encoding apparatus determines that only the subset is used, and periodically inserts a flag indicating the determined subset and the number of coefficient data into data transmitted to the image prediction decoding apparatus. May be notified to the image prediction decoding apparatus.

(G) The prediction block is stored in the block memory and selected from previously restored blocks in accordance with the above criteria, and the coefficient data of each block is the quantization step size of the current block to be encoded. And a ratio equal to the ratio of the quantization step size of the prediction block. (H) The prediction block is stored in the block memory and selected from previously restored blocks according to the above criteria, and the coefficient data of each block may be weighted with different weighting functions. (I) The prediction block may be stored in the block memory and selected from a previously restored block according to the above criteria, and a predetermined conversion operation may be performed on 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) The scanning method includes (i) a horizontal scan in which coefficient data is scanned from left to right for each row, starting from 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 in the rightmost column for each column from the top row to the bottom row; and (iii) the coefficient data is The method may include at least one of a zigzag scan performed in a diagonal direction from the leftmost coefficient data to the rightmost coefficient data in the bottom row.

(L) The prediction block is stored in the block memory and selected from the previously restored block in accordance with the above-described criterion, and the prediction mode of the prediction block is (i) higher than the current block to be processed. A first mode in which only the uppermost and leftmost coefficient data representing the average value of the block, referred to as DC coefficients, from the block located at From the block located
A second mode using only DC coefficients for prediction;
(Iii) a third mode in which a DC coefficient and zero or more AC coefficients including high-frequency components from the top row of a block located above the current block to be processed are used for prediction; iv) a fourth mode in which DC coefficients and zero or more AC coefficients including high frequency components are used for prediction from the leftmost column of the block located on the left side of the current block to be processed. The method may include at least one prediction mode, and the coefficient data of the prediction error may be scanned by a zigzag scan method.

(M) The prediction block is stored in the block memory and selected from the previously restored block according to the above-described criterion, and the coefficient data of the prediction error is
The prediction mode for scanning according to one of the above-described scanning methods and predicting the coefficient data of the prediction error is (i)
A first mode in which only DC coefficients in a block located above the current block to be processed are used for prediction, and a scan process is performed by zigzag scan on the coefficient data of the prediction error; (ii) A) 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 a block located above the current block to be processed are used for prediction, and the coefficient data of the prediction error is used for the prediction error coefficient data. A third mode in which scan processing is performed in horizontal scan, and (iv) a left mode from the current block to be processed. DC coefficient in the leftmost column of the block to be placed and zero or more A's including high-frequency components
A fourth mode in which a C coefficient is used for prediction and a scan process is performed in vertical scan on the coefficient data of the prediction error, may be included.

(N) When restoring the original image data by forming a two-dimensional array of pixels from a plurality of groups of four interleaved blocks based on the decoded image data, All odd-numbered pixels in the second 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. From
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 of the present invention, it is very effective to reduce or eliminate redundancy in the DCT transform area beyond adjacent blocks. , The number of bits used is reduced, and as a result, 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 coding apparatus and the image predictive decoding apparatus have been described. However, the present invention is not limited to this, and the constituent elements such as each unit and each unit in the image predictive coding apparatus described above. May be an image prediction encoding method including a step in which each step is replaced with each step, or an image prediction method including a step in which constituent elements such as each unit and each unit in the image prediction decoding apparatus are respectively replaced with each step A decoding method may be used. 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) or 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 which records a program including each step in the above-mentioned image prediction encoding method and / or the above-mentioned image prediction decoding method.
The recording medium has, for example, a disk shape in which a recording area is divided into sector shapes or a recording area is divided into individual blocks in a spiral shape, and, 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.

[0235]

As described above in detail, according to the image predictive encoding apparatus of the present invention, a dividing means for dividing inputted encoded image data into image data of a plurality of adjacent small areas, When encoding the image data of the small area to be processed among the image data of the plurality of small areas adjacent to each other divided by the dividing means, the reproduced image adjacent to the image data of the small area to be processed is encoded. The image data of the playback 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 which is a difference between the image data and the image data of the optimal predicted small area, and encoding the image data of the difference small area generated by the generating means with a code Encoding means for decoding, decoding means for decoding the image data of the small difference area encoded by the encoding means, and image data of the small difference area decoded by the decoding means in the optimal prediction. Second generating means for generating image data of the reproduced small area reproduced by adding the image data to the image data of the small area. Therefore, a high-precision prediction signal can be easily generated with a small amount of computation compared to the related art 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 is obtained. Further, according to the image prediction encoding apparatus of the present invention, the sampling means for sampling the input image signal into image data of a plurality of blocks each including a pixel value of a two-dimensional array, and the image signal sampled by the sampling means Conversion means for converting the image data of the block into coefficient data of a predetermined conversion area; a block memory for storing the coefficient data of the restored block; and coefficient data of the previously reconstructed block stored in the block memory A prediction unit that forms coefficient data of a plurality of prediction blocks based on the coefficient data of the block converted by the conversion unit, based on the coefficient data of the plurality of prediction blocks formed by the prediction unit. The coefficient data of the efficient prediction block is determined, selected and output, and the selected Determining means for transmitting an indicator representing a prediction block to the image prediction decoding apparatus in the form of an instruction bit, and subtracting coefficient data of the prediction block selected by the determination means from coefficient data of the current block at the present time. A first adding means for outputting coefficient data of a prediction error of a subtraction result, a quantizing means for quantizing coefficient data of a prediction error output from the first adding means, and a prediction from the quantizing means. Encoding means for entropy encoding the error coefficient data, and transmitting the encoded prediction error coefficient data to the image prediction decoding apparatus,
An inverse quantization unit that inversely quantizes the coefficient data of the prediction error from the quantization unit and outputs the restored coefficient data of the block; and an inverse quantization unit that outputs the coefficient data of the prediction block output from the determination unit. Adding to the coefficient data of the prediction error outputted from the converting means, thereby outputting the restored coefficient data of the block and storing the data in the block memory; and outputting from the second adding means Inverse transform means for inversely transforming the coefficient data of the block to be generated to generate image data of the restored block. Therefore, it is possible to provide a new image prediction encoding device and image prediction decoding device that increase the current encoding 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. Further, according to the image prediction encoding apparatus of the present invention, the sampling means for sampling the input image signal into image data of a plurality of blocks each including a pixel value of a two-dimensional array, and the image signal sampled by the sampling means Conversion means for converting the image data of the block into coefficient data of a predetermined conversion area; a block memory for storing the coefficient data of the restored block; and coefficient data of the previously reconstructed block stored in the block memory A prediction unit that forms coefficient data of a plurality of prediction blocks based on the coefficient data of the block converted by the conversion unit, based on the coefficient data of the plurality of prediction blocks formed by the prediction unit. Efficient prediction block coefficient data and scan method are determined, selected and output. Determining means for transmitting an indicator indicating the selected prediction block and the scanning method to the image prediction decoding apparatus in the form of an indication bit; and transmitting coefficient data of the prediction block selected by the determination means at the current time. First adding means for outputting coefficient data of a prediction error resulting from the subtraction by subtracting the coefficient data of the block, and quantization means for quantizing the coefficient data of the prediction error output from the first adding means Scanning means for performing scan processing on the coefficient data of the prediction error from the quantization means by the scanning method determined by the determination means, and outputting coefficient data of the prediction error after the scan processing; Entropy coding is performed on the coefficient data of the prediction error after the scanning process output from the scanning means, and the encoded prediction error Encoding means for transmitting the number data to the image predictive decoding device; dequantizing means for dequantizing the coefficient data of the prediction error from the quantizing 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 stored in the block memory. Second
And an inverse transforming means for inversely transforming the coefficient data of the block output from the second adding means 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.

[Brief description of the drawings]

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. 3 is a schematic diagram when an input image input to the image predictive encoding device in FIG. 1 is divided into triangular regions.

FIG. 4 is a block diagram showing a configuration of a first embodiment of a prediction signal generator used in the image prediction encoding device of FIG. 1;

FIG. 5 is a block diagram showing a configuration of a second embodiment of the prediction signal generator used in the image prediction encoding device of FIG. 1;

FIG. 6 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. 7 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;

FIG. 8 is a block diagram illustrating a configuration of an image prediction encoding device according to a second embodiment of the present invention.

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 significant pixels.

FIG. 10 is a schematic diagram showing an example of an input image input to the image predictive encoding device of FIGS. 1 and 8, which has significant pixels.

FIG. 11 is a schematic diagram showing an example of an input image input to the image predictive encoding device of FIGS. 1 and 8 and having an insignificant pixel;

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

FIG. 13 is a block diagram illustrating a configuration of an image prediction decoding device according to a fourth embodiment of the present invention.

FIG. 14 is a block diagram illustrating a configuration of a conventional image prediction encoding device.

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

FIG. 16 is a block diagram illustrating a configuration of an image prediction encoding device according to a fifth embodiment of the present invention.

FIG. 17 is a block diagram illustrating a configuration of an image prediction encoding device according to a sixth embodiment of the present invention.

FIG. 18 is a block diagram illustrating a configuration of a DCT transform area prediction circuit in FIGS. 16 and 17;

19 is a schematic diagram of an image showing an example of an encoding method of DC / AC prediction in the DCT transform domain prediction circuit of FIG.

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

21 is a diagram showing DC in the image prediction decoding apparatus of FIG.
It is a flowchart which shows the decoding method of / AC prediction.

FIG. 22 is a block diagram illustrating a configuration of a conventional image prediction encoding device.

FIG. 23 is a block diagram illustrating a configuration of a conventional image prediction decoding apparatus.

FIG. 24 is a block diagram illustrating a configuration of an image prediction encoding device according to an eighth embodiment of the present invention.

FIG. 25 is a block diagram illustrating a configuration of an image prediction decoding apparatus according to an eighth embodiment of the present invention.

FIG. 26 is a schematic diagram of an image showing a structure of a macroblock and a block of a frame and showing a block prediction method in the eighth embodiment.

FIG. 27 is a schematic diagram of an image for explaining the order of horizontal scanning used for coefficient scanning in the eighth embodiment.

FIG. 28 is a schematic diagram of an image for explaining the order of vertical scanning used for coefficient scanning in the eighth embodiment.

FIG. 29 is a schematic diagram of an image for explaining the order of zigzag scanning used for coefficient scanning in the eighth embodiment.

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

FIG. 31 is a schematic diagram of an image showing a relationship between blocks in an implicit mode determination according to the eighth embodiment.

[Explanation of symbols]

 Reference numeral 101: input terminal, 102: 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 ... Predicted 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: 904, an inverse quantizer, 905, an inverse DCT converter, 906, an adder, 907, an output terminal, 908, a controller, 909, a motion compensator, 910, a prediction signal generator, 911, a line memory, 912: frame memory, 913: switch, 922: prediction signal generator, 923: motion compensator, 990: shape decoder, 1001: block sampling unit, 1002: motion detection unit, 1003: compensation unit, 1004: DCT transform Unit 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 transform unit, 1015 quantizer unit, 1016 adder, 1017 DCT transform area prediction unit, 1018 block memory, 1019 adder, 1020 entropy VLC encoding 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 transform unit, 1029 ... Adder, 1030 ... Quantum 1031 DCT transform region prediction unit 1032 Block memory 1033 Inverse quantization unit 1034 Entropy VLC encoding unit 1035 Adder 1036 Inverse DCT transform 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 domain prediction unit, 1054 block memory, 1055 inverse DCT transform 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 transform unit, 2 34 quantization unit 2035 adder 2036 H / V / Z scan unit 2037 entropy VLC coding 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 transform 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.

Continuation of the front page (72) Inventor Tio Ken Tan Singapore 470601, Singapore, Bedok Reservoir Road Block 601 08-506 (56) Reference JP-A-63-187185 (JP, A) JP-A-2 -65583 (JP, A) JP-A-10-224804 (JP, A) JP-A-10-108188 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N ^7/ 24- 7/68 H04N 1/14-1/419

Claims (2)

(57) [Claims] 1. A two-dimensional sequence of image data which is divided into blocks.
A conversion step of converting the conversion coefficient into a conversion coefficient of
A quantization step of obtaining a transformed coefficient, and an upper block (A) or a left block adjacent to the current block.
A of the current block from one of the locks (B)
A switch for adaptively selecting a prediction block whose C coefficient is to be predicted.
Step and the AC coefficient of the prediction block
Quantization step size and prediction block quantization step size.
Scaling by the ratio of the map size and the AC coefficient of the scaled prediction block,
The AC coefficient of the current block is predicted to
Calculating the difference, and calculating the AC prediction error obtained by the AC coefficient prediction using a variable-length code.
Encoding the image.
Encoding method. 2. An image predictive coding method for coding image data.
An apparatus for converting image data that has been blocked into two-dimensional sequence conversion coefficients.
And a conversion unit that quantizes the conversion coefficient of the two-dimensional sequence and converts the quantized conversion coefficient.
A quantizer for obtaining a permutation coefficient and an upper block (A) or a left block adjacent to the current block.
A of the current block from one of the locks (B)
Selection of adaptively selecting a prediction block for predicting a C coefficient
Selection means and the AC coefficient of the prediction block
Quantization step size and prediction block quantization step size.
Scaling that scales according to the ratio of the tap size
Means, and from the AC coefficients of the scaled prediction block,
The AC coefficient of the current block is predicted to
And AC coefficient predicting means for obtaining a difference, the AC prediction error obtained by the AC coefficient prediction unit variable
And a variable-length encoder for performing long encoding .