JPH04316292A - High efficiency coding device for video signal - Google Patents

Abstract

PURPOSE:To achieve the coding abundant in the generalization without depending on an image by preparing a representative block list without any deviation when the coding is performed by the matching with a representative block. CONSTITUTION:The inputted image data are divided into blocks by a blocking device 1, divided into plural areas by an area divider 2, a representative block is selected from the boundary part of the area and the address is registered to a list 4. Next, the decoding picture element value of the representative block corresponds to the address of the list 4, stored into a representative block memory 5, and since the list represents the internal part and the boundary of each divided area, the deviation when matching is obtained is small, and the small coding block without the corresponding representative block is enough. When the coding is performed, in the registered order, a differential value of the representative block is counted by a subtracter 6, the size of an allowable error value is decided by a comparator 7, and the address of the selected representative block is transmitted to a quantizing device 8. When the representative block lower than the allowable value exists, the coding is performed in the block by using an auxiliary coder 9.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly efficient encoding device for video signals.

0002

2. Description of the Related Art One of the highly efficient coding methods for video signals is to compare or copy a previously decoded portion.

[0003] This method divides the screen into small blocks, sequentially compares each block with representative blocks selected from previously decoded blocks and registered in a list, selects the one with the least distortion, and then It encodes addresses.

FIG. 3 is a block diagram of an encoder for explaining a conventional high-efficiency encoding method for video signals. 1 is a block generator, 15 is a list, 16 is a representative block memory,
17 is a subtracter, 18 is a comparator, 19 and 20 are quantizers,
21 is an auxiliary encoder, 22 is an auxiliary decoder, and 23 is an address controller.

FIG. 2 is a diagram schematically representing a video signal. The input image data is divided by a block generator 1 into blocks such as 4 pixels vertically by 4 pixels horizontally.

Among the decoded blocks, addresses of representative blocks as shown in FIG. 2 are stored in a list 15 in advance. The decoded pixel values of the representative blocks are stored in the representative block memory 16 in association with the addresses of the list.

[0007] For blocks to be encoded, a subtracter 17 calculates a difference value between the block and the representative block in the order registered in the list 15 .

The calculated difference values are sequentially judged by a comparator 18 as to whether they are larger or smaller than a predetermined constant value, that is, a permissible error value. When a representative block whose difference value is less than the allowable error value is determined, the calculation of the difference value and the comparison with the allowable error value are terminated, and the address of the selected representative block is transmitted from the list 15 to the quantizer 19.

[0009] In the list, the order is changed so that the address of the representative block selected most times is placed at the top. Addresses that overflow from the list are deleted from the bottom.

If there is no representative block whose error value is less than the allowable error value, the auxiliary encoder 21 performs encoding only within the block to be encoded, and transmits the result to the quantizer 20. The address of the block at this time is newly registered in list 2 as one of the representative blocks. At the same time, the block at this time is decoded by the auxiliary decoder 22 corresponding to the auxiliary encoder 21, and the list 15
is stored in the representative block memory 16 as the decoded pixel value of the block corresponding to the address.

[0011]

However, in the conventional method, there is a possibility that representative blocks are generated unbalanced, and it cannot be said to be general-purpose for all images. Furthermore, if an attempt is made to encode moving images or continuously transmitted images using the same code table, there is a risk that the amount of code for each image and the quality of the reproduced image will differ greatly.

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a highly efficient encoding method for video signals that is more versatile than the conventional method and is equally efficient for different images and moving images.

[0013]

[Means for Solving the Problems] The present invention provides means for dividing a screen into a plurality of regions based on a certain feature value, means for extracting a block representative of the region from each divided region, and means for registering the address of the representative block in a list; means for calculating the difference value between the representative block and the block to be encoded in the order stored in the list; and the calculated difference value and a predetermined constant value. means for transmitting an address at the time when the difference value as a result of the comparison was less than or equal to a constant value; and means for transmitting the address of the representative block at the time when the difference value as a result of the comparison was less than or equal to the constant value; means for transmitting the value; means for auxiliary encoding of the block when there is no representative block below the constant value; and means for newly registering the block in a list as one of the representative blocks. This is a highly efficient video signal encoding device characterized by having a means for changing the order in the list so that the address of a representative block that transmits addresses with high frequency is placed at the top. means for dividing into areas; means for extracting a block representative of the area from each divided area; means for registering the addresses of the extracted representative blocks in a list; means for calculating a difference value between the representative block and the block to be encoded; and means for comparing the calculated difference value with a predetermined constant value;
A block to be encoded and a representative block registered in the list, characterized by having means for transmitting the address of the representative block and the difference value at the time when the difference value as a result of the comparison was less than or equal to a constant value. an address of the representative block with the smallest calculated difference value and means for quantizing the difference value; means for transmitting the address and the difference value, means for auxiliary encoding of the block when there is no representative block below the constant value, and means for newly listing the block as one of the representative blocks. The present invention is a highly efficient video signal encoding device characterized by having means for registering and means for changing the order in the list so that addresses of representative blocks whose addresses are transmitted with high frequency are placed at the top.

[0014]

According to the present invention, by using the above-described apparatus, an unbiased list can be created by obtaining representative blocks from regions having different feature amounts, and more versatile encoding can be performed.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (FIG. 1) is a block diagram of an encoder for explaining a high-efficiency encoding method for video signals in a first embodiment of the present invention. In the figure, 1 is a block generator, 2 is a region divider, 3 is a representative block selector, 4 is a list, 5 is a representative block memory, 6 is a subtracter, 7 is a comparator, 8, 11
is a quantizer, 9 is an auxiliary encoder, and 10 is an auxiliary decoder.

The input image data is processed by a block generator 1.
The image is divided into blocks of 4 pixels vertically by 4 pixels horizontally, and the area divider 2 divides the image into a plurality of areas as illustrated in FIG. 3. The feature amount for determining region division is arbitrary. Here, it is assumed that area division is performed using equiluminance contour lines.

The representative block selector 3 selects a block representative of each divided area from the center of the area as illustrated in FIG. 3. A representative block is also selected from the boundary of the area. The address of the selected representative block is registered in list 4.

The decoded pixel values of the representative block are stored in the representative block memory 5 in association with the addresses of the list. In addition, as shown in FIG. 3, the neighborhood area of the block to be encoded is determined, its address is stored in list 4, and the decoded pixel value of that address portion is read out and stored in representative block memory 5. I'll keep it.

[0019] Since the list created as described above represents the interior and boundaries of each divided area, there is less bias when performing matching, and it is possible to reduce encoded blocks for which there is no corresponding representative block. can.

By registering representative blocks of a large area, ie, an area containing more blocks, at the top of the list, searching becomes easier and faster when encoding each block.

Next, each block is encoded. The subtracter 6 calculates the difference value between the block to be encoded and the representative block in the order in which it is registered in the list 4.

The calculated difference values are sequentially judged by a comparator 7 as to whether they are larger or smaller than a predetermined constant value, that is, a permissible error value. When a representative block whose difference value is less than the allowable error value is determined, the calculation of the difference value and the comparison with the allowable error value are terminated, and the address of the selected representative block is transmitted from list 4 to the quantizer 8. .

In the list, the order is changed so that the address of the representative block selected most times is placed at the top. Addresses that overflow from the list are deleted from the bottom.

If there is no representative block that is less than the allowable error value, the auxiliary encoder 9 performs encoding only within the block to be encoded, and transmits the result to the quantizer 11. The address of the block at this time is newly registered in list 4 as one of the representative blocks. Auxiliary decoder 10 simultaneously corresponding to auxiliary encoder 9
The block at this time is decoded and stored in the representative block memory 5 as the decoded pixel value of the block corresponding to the address in the list 4.

[0025] When a representative block is selected for the encoded block, the correlation between the blocks that follow the encoded block and the blocks that follow the selected representative block is further investigated.

[0026] The block to the right of the encoded block and
The difference value of the block to the right of the selected representative block is similarly calculated using the subtractor 5, and the difference value and the tolerance are judged by the comparator 7. If the difference value is less than the tolerance, the previous block is A code indicating that the block is consecutive to the representative block is transmitted. In this case, the same determination is repeated for the block on the right until the allowable error is exceeded.

If the error is greater than the allowable error, a code indicating non-continuity is transmitted, and the block at that time is compared with each representative block in sequence.

FIG. 2 is a block diagram of an encoder for explaining a high-efficiency encoding method for video signals in a second embodiment of the present invention. In the figure, 1 is a block generator, 2 is a region divider, 3 is a representative block selector, 4 is a list, 5 is a representative block memory, 6 is a subtracter, 7 is a comparator, 8, 1
1 is a quantizer, 9 is an auxiliary encoder, 10 is an auxiliary decoder, 12 is a local decoder, 13 is a memory, and 14 is an encoder.

The input image data is divided into blocks and divided into a plurality of regions as in the first embodiment.

The representative block selector 3 selects a block representative of each divided area from the center of the area as illustrated in FIG. 3. A representative block is also selected from the boundary of the area. The address of the selected representative block is registered in list 4.

The decoded pixel values of the representative block are stored in the representative block memory 5 in association with the addresses of the list. In addition, as shown in FIG. 3, a neighboring area of the block to be encoded is determined, its address is stored in the list 4, and the decoded pixel value of that address portion is read out from the memory 13, and the representative block memory 5 Remember it.

Next, each block is encoded. The subtracter 6 calculates the difference value between the block to be encoded and the representative block in the order in which it is registered in the list 4.

The calculated difference values are sequentially judged by the comparator 7 as to whether they are larger or smaller than a predetermined constant value, that is, a permissible error value. When a representative block whose difference value is less than the allowable error value is determined, the calculation of the difference value and the comparison with the allowable error value are terminated, and the address of the selected representative block is transmitted from list 4 to the quantizer 8. . At the same time, the encoder 14 encodes the difference value at that point, and the quantizer 8
to be transmitted.

Furthermore, using the encoded difference value and the selected representative block, the local decoder 12 decodes the encoded block and stores it in the memory 13. The decoded signal stored in the memory 13 is used for encoding subsequent blocks.

In the list, the order is changed so that the address of the representative block selected most times is placed at the top. Addresses that overflow from the list are deleted from the bottom.

If there is no representative block that is less than the allowable error value, the auxiliary encoder 9 performs encoding only within the block to be encoded, and transmits the result to the quantizer 11. The address of the block at this time is newly registered in list 4 as one of the representative blocks. Auxiliary decoder 10 simultaneously corresponding to auxiliary encoder 9
The block at this time is decoded and stored in the representative block memory 5 as the decoded pixel value of the block corresponding to the address in the list 4.

[0037] When a representative block is selected for the encoded block, the correlation between the blocks that follow the encoded block and the blocks that follow the selected representative block is further investigated.

[0038] The block to the right of the encoded block and
The difference value of the block to the right of the selected representative block is similarly calculated using the subtractor 5, and the difference value and the tolerance are judged by the comparator 7. If the difference value is less than the tolerance, the previous block is A code indicating that the block is consecutive to the representative block is transmitted. In this case, the same determination is repeated for the block on the right until the allowable error is exceeded.

If the error is greater than the allowable error, a code indicating that the blocks are not continuous is transmitted, and the block at that time is compared with each representative block in sequence.

In the first and second embodiments, the blocks are divided into 4×4 pixels, but the size of the blocks is arbitrary.

[0041] In addition, in the first and second embodiments, area division was performed using the luminance value, but this is based on the amount of energy,
A feature quantity such as an entropy quantity may also be used.

[0042] Further, the method of auxiliary encoding in the first and second embodiments is arbitrary. Further, the range of the neighboring region in the first and second embodiments is arbitrary.

Furthermore, the method of encoding the difference value in the second embodiment is arbitrary.

[0044]

[Effects of the Invention] As explained above, according to the present invention,
By performing region division and obtaining representative blocks from regions with different feature values, it is possible to create an unbiased list, and the number of coded blocks without corresponding representative blocks can be reduced, making it more versatile. It is possible to perform rich encoding.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an encoder for explaining a high-efficiency encoding method of a video signal in a first embodiment of the present invention.

FIG. 2 is a configuration diagram of an encoder for explaining a high-efficiency encoding method of a video signal in a second embodiment of the present invention.

FIG. 3 is a schematic diagram of a video signal for explaining a high-efficiency encoding method of a video signal in the first and second embodiments of the present invention.

FIG. 4 is a configuration diagram of an encoder for explaining a conventional high-efficiency encoding method of a video signal.

[Explanation of symbols]

2 Area divider 3 Representative block selector 4 List 5 Representative block memory 6 Subtractor 7 Comparator 9 Auxiliary encoder

Claims (4)

[Claims] 1. Means for dividing a screen into a plurality of regions based on a certain feature amount, means for extracting a block representative of the region from each divided region, and registering the address of the extracted representative block in a list. means for calculating a difference value between the representative block and the block to be encoded in the order stored in the list;
means for comparing the calculated difference value with a predetermined constant value; means for transmitting an address at a point in time when the difference value as a result of the comparison was less than or equal to the constant value; A means for auxiliary encoding of the block when the block is registered, a means for registering the block as a new representative block in the list, and a means for ensuring that the addresses of representative blocks whose addresses are transmitted with high frequency are placed at the top. 1. A high-efficiency encoding device for a video signal, comprising means for changing the order in the list. 2. Means for dividing a screen into a plurality of regions based on a certain feature amount, means for extracting a block representative of the region from each divided region, and registering the address of the extracted representative block in a list. means for calculating a difference value between the representative block and a block to be encoded in the order stored in the list; and means for comparing the calculated difference value with a predetermined constant value; A means for transmitting the address of the representative block at the time when the difference value as a result of the comparison is less than the constant value, and means for transmitting the difference value, and auxiliary encoding of the block when there is no representative block whose difference value is less than the constant value. , means for newly registering the block as one of the representative blocks in the list, and means for changing the order in the list so that the addresses of representative blocks that transmit addresses with high frequency are placed at the top. Features: High-efficiency encoding device for video signals. 3. In the high-efficiency video signal encoding device according to claims 1 and 2, when encoding a new screen, the area divided in the previous screen and the area divided in the current screen are compared. 3. The high-efficiency video signal encoding apparatus according to claim 1, wherein the registration is updated every time there is a newly generated area or a disappeared area. 4. The high-efficiency coding device for video signals according to claims 1 and 2, characterized in that the sizes of the divided regions are compared and the representative blocks of the largest regions are registered at the top of the list in order. 3. A high-efficiency video signal encoding device according to claim 1.