JPH05336382A - In-frame encode/decode system - Google Patents

Abstract

PURPOSE:To improve encoding efficiency for image information, etc., by introducing block matching. CONSTITUTION:At a transmission side, an image signal outputted from a TV camera 1 is accumulated in frame memory 3. The image signal is segmented from the memory 3 at every block, and the block matching is applied to it at a block matching circuit 11. The difference of the blocks is taken based on a block matching result. The encoding is applied to the signal by a DCT converter 6 and a quantizer 7, and the multiplexing of a remainder signal with a matching vector is performed by a multiplexer 12, then, it is sent out. At a reception side, the remainder signal is separated from the matching vector by a multiplex separator 14, and the block is reproduced by a reverse quantizer 15 and a DCT reverse converter 16, and it is assembled at a block adder circuit 18, and a reproducing image is outputted to a monitor 41.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intraframe coding / decoding system for moving images and still images.

[0002]

2. Description of the Related Art In the intra-frame coding method, when a still image or a moving image is coded, a predicted value is generated from one image signal (frame) to be coded, and the predicted value is subtracted from the input image signal. This is a method in which the obtained residual signal is quantized, coded, and transmitted. The intra-frame decoding method is a method of receiving the transmitted signal and decoding it to restore the original frame. Conventionally, intraframe coding / decoding is performed by the following method.

FIG. 2 is a block diagram showing an example of the configuration of a conventional encoder and decoder. As shown in FIG. 2A, the original image is input by the TV camera 21, and its output signal is converted into a digital image signal by the A / D converter 22.
The digital image signal is stored in the input frame memory 23 for one frame, and the average value circuit 24 obtains the average pixel value in the block for each processing block of 16 × 16 pixels. The average value in the block is quantized by the quantizer 25,
It is inversely quantized by the inverse quantizer 26, passes through the interpolation circuit 27, and is subtracted from the input image by the adder 28. The residual signal from which the average value has been subtracted is quantized and encoded by the quantizer 29, and transmitted to the transmission line 31 together with the intra-block average value that is quantized and encoded by the multiplexer 30.

As shown in FIG. 2B, the decoder receives the code from the transmission line 32, and the demultiplexer 33 separates the average value and the code of the residual signal. The average value and the residual signal are dequantized by the dequantizers 34 and 35. The average value is stored in the interpolation circuit 36 and added to the residual signal,
It becomes a reproduction signal. The reproduction signal is output to the output frame memory 38.
After one frame is stored in the D / A converter 39, it is converted into an analog image signal by the D / A converter 39 and output to the TV monitor 40 (for example, Kato: “Improvement of coding efficiency of average value separation type block coding method”) The 70th anniversary general conference of the Institute of Electronics, Information and Communication Engineers, lecture number 1158 (1987)).

[0005]

However, the above-mentioned conventional techniques have the following problems. That is, in the above-mentioned technique, the intra-block average value and the residual signal are quantized and transmitted, but the pixel correlation in the frame is not used at the time of encoding. Therefore, there is a problem that the coding efficiency is low. The present invention has been made in view of the above points, and an object thereof is to provide an intraframe coding / decoding method with high coding efficiency.

[0006]

According to the intraframe coding / decoding method of the present invention, a frame to be coded is divided into a plurality of blocks, and among the plurality of divided blocks,
While encoding and transmitting some predetermined blocks, the code is decoded, the remaining blocks other than the predetermined block are shifted by a predetermined amount in the vertical or horizontal direction on the decoded block, By comparing with the predetermined block, a minimum residual signal between the remaining block and the predetermined block is obtained, the residual signal is encoded and transmitted together with the predetermined block, and the remaining block is Sending a signal indicating a deviation from a predetermined block, and receiving and decoding some predetermined blocks and a residual signal among a plurality of divided blocks of an encoded frame, A signal indicating a deviation from a predetermined block is received, a block at a deviation position indicated by the signal and a residual signal are added to generate a block, and the raw signal is generated. It is characterized in that to restore the frame by combining the blocks with the predetermined block.

[0007]

In the intra-frame coding / decoding system of the present invention, when the data such as the image photographed by the TV camera is coded on the transmitting side, the frame is 8 × 8 pixels or 16 frames.
It is divided into processing blocks such as × 16 pixels. And
The predetermined block is directly subjected to discrete cosine transform and quantized. The other blocks are matched with a predetermined block that is dequantized and reproduced, and the smallest residual and the matching vector at that time are obtained. These signals are multiplexed and sent to the transmission line. On the other hand, on the receiving side, the signal received from the transmission path is separated into the matching vector and the transform coefficient code. The transform coefficient code is dequantized and reproduced into a reproduction signal block and a residual signal block. Then, the reproduction signal block is added to the residual signal block based on the matching vector information, and the final reproduction image is output.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram of an embodiment of an intra-frame coding / decoding method according to the present invention. As shown in FIG. 1A, an original image is input to the TV camera 1, and its output signal is converted to a digital image signal by the A / D converter 2. The digital image signal is stored in the input frame memory 3 for one frame, and is subjected to the discrete cosine transform (DCT) by the switch 4 for each processing block of 8 × 8 pixels or 16 × 16 pixels and the like by block matching. It is divided into blocks where residuals can be taken. The switch 5 directly transforms the input by discrete cosine transform, or
It is a switch for selecting whether to perform the discrete cosine transform of the residual signal.

The DCT converter 6 performs a discrete cosine transform on the image signal or the residual signal. What is the discrete cosine transform?
Converting spatial domain data to frequency domain data. In addition to the discrete cosine transform, there is a fast Fourier transform (FFT) or the like. The transform coefficient is quantized and encoded by the quantizer 7 and transmitted by the multiplexer 12. When the switch 4 selects the terminal A and the switch 5 selects the terminal B (when the input image is directly subjected to the discrete cosine transform), the inverse quantizer 8 dequantizes the code and the DCT inverse transformer 9 reproduces the image. Input to the frame memory 10. When the terminal C is selected by the switch 4 and the terminal D is selected by the switch 5 (when the input image is subjected to the discrete cosine transform as it is), the input image signal block is block-matched with the contents of the frame memory 10 by the block matching circuit 11. The block matching circuit 11 finds a matching vector that gives the smallest residual and outputs it to the multiplexer 12. The residual signal block obtained as a result is sent to the switch 5. The switch 5 is tilted to the terminal D side, and the residual signal block is sent to the transmission line 13 by the multiplexer 12 via the DCT converter 6 and the quantizer 7. The above is the configuration on the encoder side.

Next, description will be made on the decoder side. Figure 1
As shown in (b), the code is received from the transmission line 13,
The demultiplexer 14 separates the matching vector and the transform coefficient code. The transform coefficient code is inversely quantized by the inverse quantizer 15. Further, the DCT inverse converter 16 reproduces the reproduced signal block and the residual signal block, and the frame memory 1
Stored in 7. Next, the block addition circuit 18 calculates, based on the matching vector information from the demultiplexer 14,
The reproduction signal block is added to the residual signal block, and the final reproduced image is output to the frame memory 19. The reproduced image in the frame memory 19 becomes an analog image signal by the D / A converter 20 and is output to the image monitor 41. The above is the configuration on the decoder side.

Next, the operation of the switches 4 and 5 and the block matching will be described. The switches 4 and 5 are always operated by a combination of the terminals (A, B) or the terminals (C, D), and the input signal selects the residual signal. FIG. 3 is a conceptual diagram of block matching. Figure 3
(A) shows an arrangement of blocks for performing a discrete cosine transform of an input signal (shaded blocks) and blocks for performing a discrete cosine transform of a residual signal. For encoding, the switch is turned over to the terminals (A, B), and first, from the frame memory 3,
The portion corresponding to the shaded block is sequentially cut out. Then, discrete cosine transform (DCT), quantization, dequantization,
Inverse discrete cosine transform (inverse DCT) is performed to reproduce the shaded block portion in the frame memory 10. Next, the switch is tilted to the terminals (C, D), the blocks in the white frame in the figure are sequentially cut out, and block matching is performed with the shaded blocks in the frame memory 10.

FIG. 3B shows a method of block matching. White blocks in the shaded blocks are sequentially shifted by a predetermined amount in the vertical or horizontal direction in the figure, the minimum square error is calculated each time, and the matching vector giving the smallest square error is obtained. In addition, the residual signal is obtained, and DCT,
And quantizing. Regarding the operation of the encoder, the image signal can be easily reproduced by the reverse procedure if the block positions of the diagonal lines are determined by the encoder and the decoder. As described above, since the block matching is performed by referring to the reproduced signal, the spatial redundancy of the blocks in the white frame can be reduced and the coding can be efficiently performed.

The present invention can be variously modified. For example, incorporating variable length coding in the quantizer,
Further, the effect can be further enhanced by combining with the inter-frame predictive coding. What is variable length numbering?
It means to shorten the length of the code as a whole by changing the number of bits of the code according to the probability that the signal appears.
Inter-frame predictive coding refers to coding in which a continuous frame such as a moving image is reproduced with the residual from the previous frame and the code of the previous frame to reproduce the next frame.

[0014]

As described above, according to the intraframe coding / decoding method of the present invention, block matching is introduced during intraframe predictive coding.
Coding can be performed with reduced spatial redundancy. Therefore, the coding efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of an intraframe coding / decoding method according to the present invention.

FIG. 2 is a block diagram showing an example of configurations of a conventional encoder and decoder.

FIG. 3 is a conceptual diagram of block matching.

[Explanation of symbols]

 1 TV camera 2 A / D converter 3 Input frame memory 4, 5 switch 6 DCT converter 7 Quantizer 8, 15 Inverse quantizer 9, 16 DCT inverse converter 10, 17, 19 Frame memory 11 Block matching circuit 12 multiplexer 13 transmission line 14 demultiplexer 20 D / A converter 41 image monitor

Claims (2)

[Claims] 1. A frame to be encoded is divided into a plurality of blocks, some predetermined blocks of the divided plurality of blocks are coded and transmitted, and the codes are decoded to obtain the predetermined block. The remaining blocks other than the block are compared with the predetermined block while shifting in the vertical or horizontal direction by a predetermined amount on the decoded block, and the minimum remaining between the remaining block and the predetermined block. An intraframe coding method characterized in that a difference signal is obtained, the residual signal is encoded and transmitted together with the predetermined block, and a signal indicating a deviation between the remaining block and the predetermined block is transmitted. .. 2. A plurality of predetermined blocks of a plurality of divided blocks of a coded frame and a residual signal are received and decoded, and a signal indicating a deviation from the predetermined block is received. A frame characterized by receiving, adding a block at a shifted position indicated by the signal and a residual signal to generate a block, and combining the generated block and the predetermined block to restore a frame Inner decoding method.