JPH11220730A - Encoding method and device thereof, decoding method and device and recording medium thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce memory capacity and to accelerate operation by accumulating an input image in a first memory, receiving capacity information showing the maximum permission memory capacity of a second image memory, so that the repeated conversion code of an encoding image is executed, deciding the search range of the accumulated input image and repeatedly converting it, in accordance with the capacity information in the search range. SOLUTION: This encoding device 1 is provided with an image memory part 6 inputting and storing original image data, a repeated conversion encoding part 3 for encoding image data 112 and 113 and a search area deciding part 9 for deciding a search range based on maximum permission memory capacity information 102. An encoding bit stream 10 from the repeated conversion encoding part 3 is supplied to a decoding device 2 through a communication network and the decoding device 2 decides the decoding maximum permission memory capacity of an image memory part 15. The range of the inputted image to be encoded is decided, in accordance with maximum permission memory capacity information 102 given by the search area deciding part 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to an encoding method and apparatus, a decoding method and apparatus, and a recording medium, and more particularly, to an encoding method and a coding method for performing efficient image encoding for effectively transmitting an image. More specifically, the present invention relates to a decoding method and apparatus, and a recording medium.

[0002]

2. Description of the Related Art International Organization
zation for Standardization; ISO) is JPEG (Joint
Photographic Experts Group) has published a standardization system for conventional image compression. This system is called Discrete Cosine Transformation (DC)
Applying T) to the image to convert the image to DCT coefficients provides optimized coding or decoding of the image. This scheme works most efficiently when a relatively large number of bits are used to represent the encoded information. However, if the number of bits to represent the encoded information is less than a certain value, the inherent blockiness in such DCT transforms will be significant and the image quality will degrade as noticeably by the viewer. I do.

In response to these deficiencies in the JPEG and DCT procedures, a new iterative transform system (iterative function system; It)
erated Function System (IFS) has been proposed and is gaining consent. This IFS technique focuses on self-similarity between image parts and is based on fractal geometry. The IFS states that the various parts of a particular image can be of different sizes (sizes), locations,
Even in perspective or direction, it works under the assumption of similarity. IFS utilizes image redundancy to efficiently encode images without block distortions that may be generated in the JPEG scheme. Therefore, IFS
Is almost independent of the number of bits used to represent the encoded information, and the resolution during decoding is
It is also unaffected when a relatively small number of bits are used to represent the encoded information.

The basic structure of IFS is described in Arnaud E. Jaquin, “Image Coding Based on a Fractal Theory of Iter.
atedImage Transformations) ”, IEEE Transactions on
Image Processing, Vol. 1, No. 1, pp. 18-30. Further, U.S. Patent Nos. 5,347,600 and 506, all issued to Barnsley et al.
No. 5447 and No. 4941193.
The encoding and decoding devices generally described in these references will now be described with reference to FIGS. 15 and 16 of the prior art.

Referring first to FIG. 15, the conventional operation of an encoding device is shown. As shown in FIG.
The original image 300 is input to the block generation circuit 200, where it is divided into a plurality of blocks 301. All blocks 301 together completely cover the original image 300, but do not overlap each other. The original image 300 is also sent to a reduced image generation circuit 202 which creates a reduced image 307 of reduced size by methods known in the prior art. The reduced image is sent first and is stored in the reduced image storage circuit 204.

Each block 301 includes an approximate area search circuit 20
1, the approximate area search circuit determines whether there is a similar reduced image portion in the specific block 301 searched by searching the reduced image 307 stored in the reduced image storage circuit 204. As described above, this search involves searching for a portion of the reduced image 307 that has a different size, portion, perspective, or direction than the block 301 being searched. Approximate block position information 30 identifying a selected portion 305 in reduced image 307 according to a detected result indicating a successful search for the closest approximation.
6 is transmitted to the reduced image storage circuit 204. According to the result shown in this manner, the selected portion 305 of the reduced image 307 stored in the reduced image storage circuit 204 is extracted and transmitted to the rotation / inversion / level value conversion circuit 203.

In the rotation / inversion / level value conversion circuit 203, a portion 305 of the reduced image 307 is processed by rotation / inversion / level value conversion in accordance with the conversion parameter 304 supplied from the approximate area search circuit 201. The conversion parameter 304 is the selected part 3 of the reduced image 307
5 shows the conversion to the block 301 of FIG. These parameters correspond to the specific part 30 of the reduced image 307.
5 is determined when it is found to correspond closest to the block 301 being searched. When the conversion is performed by the rotation / transformation / level value conversion circuit 203, the converted reduced image 303 is sent to the approximate area search circuit 201.
As a result, the conversion parameter 304 and the approximate block position information 306 are output as the IFS code 302. Thus, the first image is input to the system and the output is
A first block of the first image is replaced with a second approximation of the reduced image.
, And at least position information for determining the position of the second block in the encoded image.

Referring next to FIG. 16, there is shown a decoding apparatus, which includes a transform parameter output from the encoding apparatus shown in FIG.
The FS code is input to the IFS code storage circuit 205 and stored. The IFS code 302 is followed by an IF
Each block is read from the S code storage circuit 205,
It is sent to the IFS code reading circuit 206. The IFS code reading circuit 206 divides the code into approximate block position information 306 and transform parameters 304, as generated by the coding device. Approximate block position information 306
Is sent to the reduced image storage circuit 204 to reproduce the area of the reduced image specified by the approximate block position information 306. The reduced image portion 305 stored in the reduced image storage circuit 204 corresponding to the specified area is
Then, the signal is transmitted to the rotation / inversion / level value conversion circuit 203 and is converted according to the conversion parameter 304 supplied from the IFS code reading circuit 206. The converted image 303 resulting from the conversion is provided by a rotation / inversion / level value conversion circuit 203.
And stored in the decoded image storage circuit 208. This procedure is performed for each block to which the IFS code has been given.

When all the IFS codes for all the blocks have been read, the IFS reading circuit 206 outputs a read end (READ OUT END) display signal to the copy control circuit 20.
Send to 7. The copy control circuit 207 counts the number of executed recursive decoding / copying operations. If this number does not reach a preset number, the copy control circuit 207 executes all the blocks in the image according to the recursive decoding procedure. A reprocessing control instruction 309 is sent to the IFS code reading circuit 206 in order to continue the composite processing of. At the same time, the reprocessing command information is sent through the control signal 311 to send the partially decoded image data 313 to the reduced image generation circuit 202 through the information path 314. The reduced image generation circuit 202 is the same as the encoding device in order to rewrite the image stored in the reduced image land storage circuit 204 and to enable the next recursive decoding step with the partially decoded reduced image data 315. A partially decoded image 315 of the image data 313 decoded by the above method is generated. When a predetermined number of recursive decoding operations have been performed, and thus a predetermined number of copying operations have been performed, reprocessing command information is sent to the switch 209 by the decoded image output control signal 311. The switch 209 outputs the decoded image data 303 from the decoded image storage circuit 208 to the image output port 3.
16 is controlled. The decoded image data 313 is composed of all the image data of the above-described decoded block that has been set a number of times in advance and recursively encoded, and the decoding is read out from the extension circuit 312 according to the control signal 312.

[0010]

In the above-mentioned conventional technique, the similarity between blocks located at arbitrary positions in the entire image and the reduced / converted image is measured, and positional information (approximation) of the most similar block is measured. Block position information) and its conversion parameters are selected from all possible candidates.
In many cases, the reference block required to decode the block is located at a distance from the block.
In such a case, a large-capacity image memory for substantially storing all the blocks of the image must be held in the decoding device and the encoding device, and the memory is frequently accessed. Accordingly, it would be advantageous to provide an improvement that overcomes the above-mentioned disadvantages.

In view of the above-mentioned problems, an object of the present invention is to provide an encoding method and apparatus, a decoding method and apparatus, and a recording medium that enable image restoration with a small-capacity memory.

[0012]

In order to solve the above-mentioned problems, an encoding method according to the present invention is a method for iteratively transform encoding each block of an image, wherein an input image is stored in a first image memory. Receiving capacity information indicating the maximum allowable memory capacity of the second image memory so as to perform iterative transform decoding of the encoded image; and determining a search range of the stored input image. And iteratively transform encoding each of the blocks according to the received capacity information within the determined search range.

According to the encoding method of the present invention, in the encoding method for iteratively transform encoding each block of an image, an input image is stored in an image memory, and capacity information indicating a maximum allowable memory capacity of the image memory. Generating an encoded bit stream by iteratively transforming each block of the image using the image memory, and outputting the generated encoded bit stream and the capacity information. It has.

An encoding apparatus according to the present invention is an encoding apparatus for iteratively transforming and encoding each block of an image. The encoding apparatus stores the input image in a first image memory and executes iterative transform decoding of the encoded image. Means for receiving the capacity information indicating the maximum allowable memory capacity of the second image memory, means for determining the search range of the stored input image, and the received capacity information within the determined search range. Means for iteratively transform-encoding each of the blocks in accordance with

An encoding apparatus according to the present invention is an encoding apparatus for iteratively transform-encoding each block of an image. The encoding apparatus includes means for accumulating an input image in an image memory, and capacity information indicating a maximum allowable memory capacity of the image memory. Means for generating an encoded bit stream by repeatedly transforming each block of the image using the image memory, and means for outputting the generated encoded bit stream and the capacity information. It has.

In a decoding method according to the present invention, in a decoding method for generating a decoded image from a code representing a block of an image subjected to iterative transform coding, a capacity indicating a maximum allowable memory capacity of an image memory so as to decode the code. Generating information and outputting the generated capacity information; receiving the code including block position information indicating the position of the image block in the image, and representing a preset conversion operation performed on the image block. Receiving a conversion parameter, and recursively converting the image block identified by the block position according to the received conversion parameter using the image memory until a preset condition is satisfied. is there.

A decoding apparatus according to the present invention is a decoding apparatus for generating a decoded image from a code representing a block of an image subjected to iterative transform coding, wherein the capacity indicating the maximum allowable memory capacity of an image memory is set so as to decode the code. Means for generating information and outputting the generated capacity information; and receiving the code including block position information indicating the position of the image block in the image and representing a predetermined conversion operation performed on the image block. Means for receiving a conversion parameter, and means for recursively converting the image block identified by the block position according to the received conversion parameter using the image memory until a preset condition is satisfied. is there.

A recording medium according to the present invention is a recording medium on which an encoding program for iteratively transform-encoding an image is recorded, wherein the encoding program stores an input image in a first image memory. Receiving capacity information indicating a maximum allowable memory capacity of the second image memory so as to perform iterative transform decoding of the encoded image, and determining a search range of the stored input image. Iteratively transforming and encoding each of the blocks according to the received capacity information within a search range.

[0019] A recording medium according to the present invention is a recording medium on which an encoding program for iteratively transform-encoding an image is recorded, the encoding program comprising: a step of storing an input image in an image memory; Generating capacity information indicating a maximum allowable memory capacity of a memory; generating an encoded bit stream by iteratively transforming each block of the image using the image memory; and generating the encoded bit stream. And outputting the stream and the capacity information.

A recording medium according to the present invention is a recording medium on which a decoding program for generating a decoded image from a code representing a block of an iteratively-transformed encoded image is recorded, wherein the decoding program decodes the code. Generating capacity information indicating the maximum allowable memory capacity of the image memory and outputting the generated capacity information, and receiving the code including block position information indicating the position of the image block in the image, and Receiving a conversion parameter representing a preset conversion operation with the block applied; and the image identified by the block position according to the received conversion parameter using the image memory until a preset condition is satisfied. Recursively transforming the blocks.

In an iterative transform coding method for coding each block of an image, an input image is stored in a first image memory. Capacity information is received indicating a maximum allowable memory capacity of the second image memory to perform iterative transform decoding of the encoded image. The search range is determined in the stored input image, and each block is iteratively transformed and coded according to the capacity information received within the determined search range.

According to one aspect of the invention, portions of the input image within the determined search area are stored in a local eye memory.

According to another aspect of the invention, the iterative transform coding comprises generating a first image block from the input image, a plurality of second image blocks from a portion of the input image within the determined search range. , Conversion of a second block by a preset operation, selection of a converted second image block most similar to the first image block, code position information indicating the position of the selected second block And the output of a conversion parameter representing the conversion of the selected second image block.

In the method of generating a decoded image from a code representing an image subjected to iterative transform coding, capacity information is generated.
The generated capacity information indicates the maximum allowable capacity of the image memory for decoding the code, and is output. According to the method of the present invention, a code and a transformation parameter are received: the code includes block position information indicating a position of the image block in the image, and a transformation parameter representing a preset transformation operation performed on the image block. I have. The image block identified by the block position information is recursively transformed according to the transformation parameters received using the image memory until a preset condition is satisfied.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an encoding method and apparatus, a decoding method and apparatus, and a recording medium according to the present invention will be described with reference to the drawings.

First, regarding the encoding and decoding apparatus,
This will be described with reference to FIG. This encoding and decoding device,
An encoding device 1 that encodes an input image and outputs an encoded bit stream 101 that is a code word bit stream, and a decoding device 2 that receives and decodes the encoded bit stream 101 to generate a decoded image. Contains.

In the encoding and decoding device, the encoding device 1
The image memory unit 6 receives and stores original image data, and the image data 11 supplied from the image memory unit 6.
It includes an iterative transform coding unit 3 for coding 2, 113 and a search range determining unit 9 for determining a search range based on the maximum allowable memory capacity information 102 used for the iterative transform coding operation. The encoded bit stream 101 from the iterative transform encoding unit 3 is supplied to the decoding device 2 via a communication network. The decoding device 2 decodes an encoded bit stream of a codeword and outputs a decoded image.
And an image memory unit 15 for storing decoded images, and a maximum allowable memory capacity for determining the maximum allowable memory capacity of the image memory unit 15 and outputting the maximum allowable memory capacity indicating the maximum allowable memory capacity for decoding. And a decision unit 140.

The operation of the encoding and decoding device will now be described. The decoding device 2 determines the decoding maximum allowable memory capacity of the image memory unit 15. Therefore, in order for the decoding device 2 to decode the coded bit stream that is coded and output by the coding device 1, the coding device 1 performs coding based on the maximum allowable memory information 102 output from the decoding device 2. Must perform the conversion operation.

Therefore, the encoding apparatus 1 converts the input image data 100 which has been digitized into the maximum allowable memory capacity information 1.
Perform iterative transform coding in the region determined by 02. This iterative transform coding will be described in detail later.

Regarding a series of processes of encoding and decoding,
Here, a description will be given with reference to the flowchart of FIG. In step S11, the maximum allowable memory capacity that can be decoded by the image memory unit 15 is determined by the maximum allowable memory capacity determination unit 140, and the maximum allowable memory capacity information 102 indicating the maximum allowable memory capacity that can be decoded is given to the encoding device 1. .
Then, in step S12, the range of the input image to be encoded is determined according to the maximum allowable memory capacity information 102 given by the search range determination unit 9, and the search range information 114 is given to the image memory unit 6. In the subsequent step S13, the input image data in the range given from the image memory unit 6 is encoded by the iterative transform encoding unit 3 into an encoded bit stream. As a result, the encoded bit stream 101 is provided to the decoding device 2.
Then, the operation proceeds to step S14. Step S14
Then, the encoded bit stream from the encoding device 1 is
The image is decoded by the iterative transform decoding unit to generate a decoded image.

An information signal transmission apparatus for transmitting an information signal (encoded bit stream) using a network will be described with reference to FIG. The information signal transmission apparatus according to the present invention encodes image data 100 to generate an encoded bit stream 101,
Transmitted to the encoding apparatus 1, a first decoding device 2 ₁ for decoding a decoded bit stream by generating a decoded image 103 received from the network 18 an encoded bit stream, the first decoding device 2 ₁ An N- _th decoding device 2 _n that performs the same function and a decoding bit stream 101
And and a other of the first decoding device 1 to transmit an information signal, a first decoding apparatus 2 ₁ and the N network 18 connected to the decoding device 2 _n of. The structure of the first encoding device 1 is the same as that of the encoding device 1 of FIG.
The structure of the N-th decoding device 2 ₁ , 2 _n is the same as that of the decoding device 2 in FIG.

The operation of the information signal transmission device of FIG.
It is explained here. From one of a plurality of decoding devices on the network 18, the image memory unit 1 of the decoding device
The maximum allowable memory capacity information 102 indicating the maximum allowable memory capacity of No. 5 is output to the network 18. For example, when the decoding is performed by the _N-th decoding device 2 _n, the maximum allowable memory capacity information from the _N-th decoding device 2 _n 102
Is transmitted to the network 18 and provided to the encoding device 1.

The coding apparatus 1 that has received the maximum allowable memory capacity information performs iterative transform coding based on the received information to generate a coded bit stream 101.
The encoding device 1 then transmits the encoded bit stream 101 over the network 18. Coded bit stream 101 is supplied to the decoding device 2 _n of the N, _N-th decoding device 2 _n and outputs the decoded image data 103.

Data received on network 18 is often transmitted in the form of packetized transmission data (packets) for efficiency.

An information signal transmission device using a network according to another embodiment of the present invention will be described with reference to FIG. The information signal transmission apparatus encodes the image data 100 to generate an encoded bit stream 101 and transmits the encoded bit stream 101 to the network. The information signal transmission apparatus decodes the encoded bit stream 101 received from the network 18 and decodes the decoded image data 103 First encoding device 2 ₁ that generates
When the _N-th decoding device 2 _n to execute the first decoding device 2 ₁ with the same functions, the encoding device 5 to transmit the encoded bit stream 101, and other information signals, the first decoder 2 It includes a network 18 connected to the _first and Nth decoding devices 2 _n , and a decoding device selection unit 10 for selecting a decoding device. The structure of the first and Nth decoding devices 2 ₁ , 2 _n is the same as the structure of the decoding device 2 of FIG. However, the structure of the coding device 5 is different from the structure of the coding device 1 of FIG. That is, as described above with reference to FIG. 1, the encoding device 1 receives the maximum allowable memory capacity information 102 from a certain encoding device 2, and the encoding device 4 has the Maximum allowable memory capacity information 1 indicating the maximum allowable memory capacity information of the located image memory unit
31 is output.

The detailed structure of the encoding device will be described below. The encoding device 5 inputs the original image data 100 as a step according to the capacity of the internal image memory unit, and encodes the original image data 100 using iterative transform encoding.
The obtained encoded bit stream 101 and the maximum allowable memory capacity information 131 indicating the maximum allowable memory capacity of the image memory unit of the encoding device 5 are transmitted to the network 18 as shown in FIG.

Each of the first and N-th decoding devices 2 ₁ and 2 _N transmits the maximum allowable memory capacity information 102 indicating the maximum allowable memory capacity of each image memory unit 15 to the network 18.

FIG. 4 also shows the decoding device selection section 18 provided in the network 18. Maximum allowable memory capacity information 13 from the encoding device 5 and the decoding devices 2 ₁ , 2 _n
Are compared, and the decoding device having the maximum allowable memory capacity of the encoding device 5 is selected by the decoding device selection unit 20. The encoded bit stream 101 is then transmitted via the network 18 to the decoding device selected by the decoding device selection unit 20. The encoded bit stream 101 is provided to the selected decoding device, and the decoded image data 103 is decoded and output therefrom.

A first specific example of the coding apparatus will now be described with reference to FIG. According to this specific example, the encoding device is configured to store the image data 100 in the image memory unit 6.
And a search range used for performing iterative transform coding based on the maximum allowable memory information 102 input from the outside and determining a search range for controlling a reading operation from the image memory unit 6 by the control signal 114. Decision part 9
And an iterative transform encoding unit 3 that performs iterative transform encoding to generate the encoded bit stream 101.
The iterative transform encoding unit 3 converts the image data 112 read from the image memory unit 6 into the first block image data 11
5 and a second block generation unit 8 that generates second block image data 119 from the image data 113 read from the image memory unit 6. . In a preferred embodiment, the second block image data is twice as large as the first image data.

The iterative transform coding unit 3 further includes a transform / generating unit 11 for mapping the second block image data to generate a transformed second block image data 107, and a transformed second block image data 107. Approximation degree measurement / threshold processing unit 10 that measures the similarity between image data 107 and image data 112
And an encoding / multiplexing unit 1 that encodes / multiplexes the number or address of the selected second block image data and the conversion parameter and outputs an encoded bit stream 101
3 is included.

The operation of the encoding device of the first embodiment will now be described with reference to the flowchart shown in FIG.
In step S31, the input image data 100 is stored in the image memory 6. In step S32, the search area determining unit 9 to which the maximum allowable memory capacity information 102 indicating the maximum allowable memory capacity is supplied from an external device such as a decoding apparatus, sets the approximate block search area in accordance with the received maximum allowable memory capacity information 102. Calculate the search range of. For example, when the maximum allowable memory capacity is 100 Kbits, 100 Kbits = 316 bits × 316 lines, so that 316 vertical directions (longitudinal) and 3
The area defined by the 16 lateral bits is the maximum allowable search range. The operation proceeds to step S33.

In step S33, an iterative transform coding operation is performed based on the determined maximum allowable search range to generate a coded bit stream.

The operation of the iterative transform encoder 3 corresponding to step S33 shown in FIG. 6 will be described with reference to the flowchart of FIG. In step S21, the control signal 11
Under the control of the control unit 12 using the image data 112
Is supplied from the image memory unit 6 to the first block generation unit 7. Further, under the control of the search range determination unit 9 using the control signal 114, the image data 113 corresponds to the position of the first image data 115 and the search range based on the maximum allowable memory capacity information 102. Second from memory unit 6
To the block generation unit 8. Then, the first block generation unit 7 generates a first block image 115 from the image data 112. Similarly, the second block image generator 8 generates second block image data 119 from the image data 113 corresponding to the search area. In the subsequent step S22, the second block image data 119 is mapped by the image conversion / generation unit 11, and the converted second block image data 107 is generated. Then, the operation proceeds to step S23.

The mapping transformation will be described below in the description of the basic theory of iterative transformation coding.

Continuing with the description of FIG. 7, in step 23, the approximation degree measurement / threshold processing unit 1 calculates an error, that is, the similarity between the converted second block data 17 and the first block image data 115. Calculate the approximation of. In the subsequent step S24, the calculated similarity degree is compared with a preset threshold value (TH). If the error is smaller than the threshold, that is, if error <TH, “YE
After the determination of S ″ is obtained, the operation proceeds to step S25. In step S25, the second block data is selected as a candidate under the control of the control unit 12 using the control signal 22,
The operation proceeds to step S26. Above condition (error <TH)
Is not satisfied, a "NO" decision is obtained and the operation proceeds to step S26.

In step S26, it is determined whether or not the mapping of all the second block image data in the search area has been completed. When the processing of all the second block image data is completed, a “YES” decision is obtained and the operation proceeds to step S
Proceed to 27. Otherwise, a "NO" decision is obtained and the operation returns to step S22 and a similar operation is performed on the next second block image data. Step S27
Then, the second block data when the error from the first block image data is minimized among all the second block image data selected as candidates is the control signal 1
The selection is made by the control unit 12 at 22, and the operation proceeds to step S28. In step S28, the number or address and the conversion parameter 121 as the position information of the selected second block image are transmitted to the encoding / multiplexing unit 12. The operation then proceeds to step S29. Step S
At 29, it is determined whether the processing of all the first block image data has been completed. When the processing of all the first block image data is completed, the processing proceeds to step S30. Otherwise, the operation returns to step S21, and the same operation is performed on the next first block image data.

In step S30, in the order of the number or address of the first block image, the number or address 12 of the selected second block image having the highest similarity is obtained.
0 and the transform parameter 121 are encoded and multiplexed, and output from the encoding / multiplexing unit 12 as an encoded bit stream 101.

The detailed operation of the search range determining section 9 will be described here. The search range determination unit 9 determines a target area from the first block image data 115 and the maximum allowable memory capacity information 102 based on the position of the first block image data as the current coded target block, and sets a search range value. (Control signal) 114 is output to the image memory unit 6.

For example, as described above, the size of the original image is 7
20 pixels x 720 lines with a maximum allowable memory capacity of 100
Kbit, the number of divided screens calculated from the maximum allowable memory information is 2 in the horizontal direction and 2 in the vertical direction (lon).
gitudinal), a total of four.

The image data 113 from the area set by the search area value 114 is output from the image memory 6 to the second block generator 8.

As shown in FIG. 8, for example, if the first block image is Rm, the search range value 114
And the image data 113 in the same area is stored in the image memory unit 6
Is read from.

Each part will now be described in detail. First, the basic theory of iterative transform coding / decoding as a technique according to an embodiment of the present invention will be described with reference to FIG.

The iterative transform coding is a description for repeatedly executing reduction (reduction) mapping from a domain block to all range blocks constituting a screen (image). In this regard, the position information and transform parameters of the closest domain block are encoded for each range block.

In FIG. 9, the range block Rk corresponds to the first block image data 115 and the domain block Dk
Corresponds to the second block image data 119. The size of the range block Rk is defined as m × n, and the size of the domain block Dk is M × N.
Is defined as FIG. 9 shows that L × L range block data exists in this image. The block size of the range block and the domain block is a factor that affects the coding efficiency, and therefore, the determination of the block size is important.

The block image conversion executed by the image conversion / generation unit 11 converts the domain block Dk into a range block Rk. If the mapping function of the block k is wk and the number of the second block images required for the mapping conversion of the entire screen is P, the image f is converted by the mapping function W of the previous image as in the following equation (1). . W (f) = w ₁ (f) ∪w ₂ (f) ∪... ∪w _P (f) (1) Therefore, W is represented by the following equation (2). W = The ^{_{∪ P k = 1 W k (}} 2) mapping function W, as long as the convergence is selected any function. To ensure convergence, reduced mapping is typically used. In addition, affine transformations are often used to simplify processing.

The domain block Dk is the range block R
When mapped by affine transformation into k is then expressed by equation (3), the actual conversion function is set to v _i.

[0057]

(Equation 1)

By the equation (3), all the conversions of the movement, reduction and enlargement in the vertical and horizontal directions between the two blocks are expressed.

The above transformation is for spatial coordinates,
The mapping conversion for image values related to density values such as brightness and color difference information is performed in the same manner. In this case, for simplicity, the relationship expressed conversion of the pixel values d _i in Dk to the pixel value r _i in Rk is represented by the following formula (4). v _i (d _i ) = c × d _i + b (4) In this equation (4), c is defined as contrast and b is defined as brightness (brightness).

In this case, the parameters c and b for realizing the minimum sum of squares of the difference from the image value r _i of the range block Rk are calculated as in the following equation (5). Σ (c × d _i + b−r _i ) ² → minimum value (5) The image conversion / generation unit 11 performs a series of operations such as rotation, vertical and horizontal movement, reduction, and enlargement expressed by Expression (3). Of the second block image data 119 in the screen.

In FIG. 9, the domain block Dk located in the lower right part of the screen is mapped to the range block Rk located in the upper left part of the screen. As a method of converting the density values of the pixels of the block, affine transformation is similarly used.

In particular, for the second block image data 119, the conversion coefficients (a _i , b, c _i , di,
ei, fi) is changed to various combinations and executed.
The second block image data 10 converted thereby
7 is obtained. Then, the similarity between the converted second block image data 107 and the first block image data 115 is measured.

As a method of measuring the similarity, the sum of the absolute values of the errors of these images is used.

A specific example of the decoding device will now be described with reference to FIG. The decoding device receives the coded bit stream and performs iterative transform decoding to generate a decoded image, an image memory unit 15 that stores decoded images processed by the iterative transform decoding, and an image memory unit. A maximum allowable memory capacity determining unit 140 that generates maximum allowable memory capacity information 102 indicating the 15 maximum allowable memory capacities.

The iterative transform decoding unit 4 decodes the received coded bit stream and demultiplexes the multiplexed bit stream, decomposing the multiplexed bit stream 117, the number or address 117 of the first block image, the number or address 120 of the second block image and the conversion parameter 120 Is generated. The conversion source block reproducing unit 14 calculates the number or address 12 of the second block image.
Based on 0, the conversion source block image data 122 is reproduced from the image data 124 supplied from the image memory unit 15. The image conversion / generation unit 11 performs a mapping conversion on the conversion source block image data 122 reproduced by the conversion source block reproduction unit 14 based on the conversion parameter 121, and stores the converted block image 123 in the image memory unit 15.
give. The control unit 16 controls the iterative transform until the number of the iterative transform decoding operation reaches a preset number.

The operation of the decoding device will now be described with reference to the flowchart of FIG. In step S41, the maximum allowable memory capacity information 1 is set as the maximum decoding capacity of the image memory unit 15 in order to store the image data to be decoded.
02 is calculated and transmitted to an external encoding device via a network. Then, the operation of the decoding device is performed in step S4.
Proceed to 2. In step S42, it is determined whether or not an encoded bit has been received from the encoding device. If an encoded bit has been received, operation proceeds to step S43. Otherwise, the process is waiting. Step S
At 43, the iterative transform operation of the decoding device is performed on the coded bits using the image memory unit, and the decoded image is output.

Next, the operation of the iterative transform decoding unit 4 corresponding to step S43 in FIG. 11 will be described with reference to FIG. In step S52, the coded bit stream 1
01 is decoded / decomposed by the decoding / decomposition unit 25 to generate the following codeword: the number or address 117 of the first block, the number or address 120 of the second block, and the conversion parameter 121. The operation proceeds to step S53.
In step S53, the conversion source block data 122 is reproduced from the image data in the image memory unit 15 based on the number or address 120 as the position information of the second block image, and is provided to the conversion generation unit 11. In step S54, the mapping conversion set by the conversion parameter 121 is performed on the conversion source block image data 122 reproduced by the conversion source block reproduction unit 14 by the image conversion / generation unit 11. A transformed block image is then generated. The operation proceeds to step S55.
Converted block image data (decoded block image) 1
Reference numeral 23 is stored in the image memory unit 15 at the position of the number or address (position information) of the first block image. In step S56, it is determined whether or not the decoding operation of the image data of all the first blocks on the image screen has been processed. If the processing of all the first block image data has been processed, the operation proceeds to step S57. Otherwise, the operation returns to step S53, and the same operation is performed on the next block image data.

In step S57, control unit 16 determines whether or not to continue the iterative conversion operation. This is determined by whether the number of iterative transformation operations has reached a preset number. If it is necessary to continue the iterative transform operation, that is, if the number of the obtained iterative transform processes that have been set in advance has not been reached, the control signal 117 is generated in the source block reproducing unit 14. Operation then returns to step S53. If the number of iterative conversion operations has reached the preset number, the process continues to step S58.

In step S58, the decoded image data 125 is finally stored in the image memory unit 15 and output by the control unit 16 as decoded image data.

A second specific example of the encoding apparatus shown in FIGS. 1 and 3 will now be described with reference to FIG. The encoding device determines the search range when performing iterative transform encoding based on the maximum allowable memory capacity information 102 and controls the image memory unit 6, based on the maximum allowable memory capacity information 102. And an iterative transform encoder 3 that performs iterative transform to generate an encoded bit stream 101. Unlike the first encoding device, the iterative transform encoding unit 3 has a local operation for temporarily storing an image read from an image memory unit 6 whose read operation is different from that of the first encoder 1. It includes a memory unit.

The iterative transform coding unit 3 includes a first block image generating unit 7 for generating a first block image 115 from image data 129 fetched from the local memory unit 17 according to the second embodiment of the present invention; Local memory unit 17
And a second block image generation unit 8 that generates second block image data from the image data 130 extracted from. The iterative transform coding unit 3 also measures an approximation similarity between the image transformed by the image transforming / generating unit 11 and the first block image and processes the threshold value, and a second approximation measuring / threshold processing unit 10. And an image converting / generating unit 11 for generating the partial image data 107 of the hemorrhoid 2 converted by storing the block image of FIG.

The encoding apparatus of the second specific example further includes a control unit 12 for controlling reading of an image from the image memory unit 6 and the local memory unit 17, and a number or address of the second block image and a conversion parameter. An encoding / multiplexing unit for encoding / multiplexing and outputting as an encoded bit stream.

The operation of the second embodiment of the coding device will now be described. This encoding device is different from the first specific example of the encoding device in that the area image data 127 is stored in the image memory unit 6 according to the search range value (control signal) 114 from the search range determination unit 9 and the control signal 123 from the control unit 12. Are transmitted to the local memory unit 17 continuously.

For example, under the conditions of the allowable memory capacity and the image size described in the first specific example of the encoding apparatus, four areas are successively read from the image memory section 6 and are read from the local memory section. 17 is temporarily stored. Thereafter, the image data 129 read from the local memory unit 17 under the control of the control unit 12 using the control signal 118
The image data 130 is provided to the first block image generation unit 7 and the second block image generation unit 8 to generate first and second block image data 115 and 119.

Image memory unit 6 and local memory unit 1
7 comprises different memory types. Since the local memory unit 17 is accessed more frequently than the image memory unit 6, the SDRAM (Synchronous Dynamic Random Acceses) is used.
s Memory) is used. In addition, the CPU (central pr
Ocessing unit) can also be used.

In the third specific example of the encoding device, the input image is temporarily stored under the control of the control unit 12 using the control signal 118 instead of the image memory unit 6 to block image data 129. Is supplied to the first block generator 7 and the block image data 130 is converted to the second block image generator 8.
And the first memory of the encoding device
And a search area determination unit 9 of the specific example.

As shown in FIG. 14, the local memory unit 1
Reference numeral 7 denotes maximum allowable memory capacity information 131 indicating the maximum allowable memory capacity of the local memory unit 17 to be output to the network.
Is also generated. The structure and operation of other parts of the third specific example are the same as those of the first and second specific examples of the encoding device,
Their description is omitted.

The operation of the third example of the coding device will now be described. The encoding device 5 is only provided with a local memory unit 17 having a relatively small memory capacity, and the capacity of the local memory unit 17 is transmitted from the encoding device to the network as the maximum allowable memory capacity information 131 of this encoding device. .

The block image data 129 and 130 read from the local memory unit 17 include first and second block generation units 7 and 7 for generating first block image data 115 and second block image data 119, respectively.
8 is supplied. Subsequent processing is the same as in the second specific example of the encoding device.

Although the encoding and decoding devices and methods according to the present invention have been illustrated with respect to block diagrams, in addition to providing each block as a physical element, all methods and devices are generally used for this purpose. It can be implemented on a computer. In this regard, the recording medium or other storage device contains operating instructions for performing the steps indicated in the encoding and decoding methods described above. Also, instead of a recording medium, a transmission channel or the like connected to a communication network is provided for receiving and transmitting data from the encoding unit and decoding the encoded data.

Specific examples of the application of the encoding apparatus and method, the decoding apparatus and method, the encoding and decoding apparatus and method, the information signal transmission apparatus, and the recording medium include a digital video disk, an image transmission / reception apparatus, an image database, and the Internet. It includes an image compression / decoding device for downloading an image from a computer, an electronic still camera, a game device, an encoding / decoding device having a display unit of a variable size display, and a software module for realizing a similar system.

As described above, the encoding / decoding device includes the encoding device having the image memory unit for storing the input image data and the search range determining unit for determining the range of the image to be repeatedly encoded. The coded bit stream is generated from the image data that is repeatedly coded in the determined range. The decoding device has an image memory unit for storing image data obtained from an encoded bit stream received from the encoding device. The decoding device also has a maximum allowable memory capacity determination unit that calculates the maximum decoding capacity of the image memory unit for iteratively transforming and decoding the encoded bit stream and outputting decoded data as decoded image data. The encoding / decoding device provides high encoding efficiency and high quality images by using a small memory capacity.

[0083]

As described above, the encoding apparatus and method, the decoding apparatus and method, and the recording medium according to the present invention perform the encoding operation even if the decoding memory has a limited capacity. It is performed in advance according to the capacity. Therefore, the memory capacity does not limit the encoding operation, and a scalable configuration is realized. In addition, the reduction of memory capacity narrows the range of searching for approximate blocks for encoding,
Fast operations are performed.

In the present invention, the encoding control is performed by the encoding apparatus based on the maximum allowable memory capacity of the decoding apparatus transmitted from one of the iterative transform decoding units of the plurality of decoding apparatuses existing on the network to the network. . Therefore, all the decoding devices on the network are effectively used. The efficiency is further improved if the processing is performed by the encoder itself.

In addition, in the present invention, one iterative transform decoding unit having the maximum allowable memory capacity that enables decoding of the encoded bit stream transmitted from the encoding device is selected from the network. Therefore, the encoding control is performed within the capacity of the image memory unit given to the encoding device, regardless of the allowable memory capacity of the decoding device. Therefore,
A network with a very high degree of freedom is obtained. Also, the coded bit stream output from the inexpensive encoding device is not decoded by the expensive decoding device, and the inexpensive decoding device is selected to provide a decoded image. Therefore, effective use of resources can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of an encoding and decoding device.

FIG. 2 is a flowchart of an encoding and decoding method.

FIG. 3 is a block diagram illustrating an information signal transmission device.

FIG. 4 is a block diagram illustrating another information signal transmission device.

FIG. 5 is a block diagram illustrating a first specific example of an encoding device.

FIG. 6 is a flowchart of a method according to a first specific example of an encoding device.

FIG. 7 is a flowchart illustrating in detail the iterative transform coding of FIG. 6;

FIG. 8 is a diagram showing a mapping relationship between blocks in an image.

FIG. 9 is a diagram showing mapping between blocks according to iterative transform coding.

FIG. 10 is a block diagram of a decoding device.

FIG. 11 is a flowchart of a decoding method.

FIG. 12 is a flowchart of iterative transform decoding of a decoding operation.

FIG. 13 is a block diagram of a second specific example of the encoding device.

FIG. 14 is a block diagram of a third specific example of the encoding device.

FIG. 15 is a block diagram of a conventional encoding device.

FIG. 16 is a block diagram of a conventional encoding device.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 Encoding device, 2 decoding device, 3 iterative transform encoder, 4 iterative transform decoder, 6 image memory unit, 9 search area determining unit, 140 maximum allowable memory capacity determining unit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akio Oba 7-1-1 Akasaka, Minato-ku, Tokyo Sony Computer Entertainment Inc.

Claims (15)

[Claims] 1. An encoding method for iteratively transform encoding each block of an image, comprising: storing an input image in a first image memory; and performing a iterative transform decoding of the encoded image. Receiving capacity information indicating a maximum allowable memory capacity of the memory; determining a search range of the stored input image; and iteratively transforming each of the blocks according to the received capacity information within the determined search range. Encoding step. 2. The encoding method according to claim 1, further comprising the step of storing a portion of said input image within said determined search range in a local memory. 3. The iterative transform encoding step includes: generating a first image block from the input image; and generating a plurality of second image blocks from a portion of the input image in the determined search area. Generating; converting the second image block by a preset operation; selecting the converted second image block most similar to the first image; Selecting a second image block corresponding to the converted second image block; outputting code position information indicating a position of the selected second image block; Outputting a conversion parameter representing a second image block.
Coding method as described. 4. An encoding method for iteratively transform encoding each block of an image, comprising: storing an input image in an image memory; generating capacity information indicating a maximum allowable memory capacity of the image memory; Generating a coded bit stream by iteratively transforming each block of an image using the image memory; and outputting the generated coded bit stream and the capacity information. Encoding method. 5. The step of performing the iterative transform coding step includes: generating a first image block from the input image; and generating a plurality of second image blocks from a portion of the input image within a higher determined search range. Generating; converting the second image block by a preset operation; selecting the converted second image block most similar to the first image; Selecting a second image block corresponding to the converted second image block; outputting code position information indicating a position of the selected second image block; Outputting a conversion parameter representing a second image block.
Coding method as described. 6. An encoding device for iteratively transform encoding each block of an image, means for storing an input image in a first image memory, and a second image for performing iterative transform decoding of the encoded image. Means for receiving capacity information indicating the maximum allowable memory capacity of the memory; means for determining a search range of the stored input image; and iteratively transforming each of the blocks according to the received capacity information within the determined search range. Encoding means having encoding means. 7. The encoding apparatus according to claim 6, further comprising means for accumulating a portion of said input image within said determined search range in a local memory. 8. The means for performing iterative transform coding includes: means for generating a first image block from the input image; and a plurality of second image blocks from a portion of the input image in the determined search area. Means for generating a second image block by a preset operation; means for selecting the converted second image block most similar to the first image; Means for selecting a second image block corresponding to the converted second image block; and outputting code position information indicating the position of the selected second image block. 7. An encoding apparatus according to claim 6, further comprising: means for outputting a transformation parameter representing the image block. 9. An encoding apparatus for iteratively transform encoding each block of an image, means for storing an input image in an image memory, means for generating capacity information indicating a maximum allowable memory capacity of the image memory, Means for iteratively transforming each of the blocks of the image using the image memory to generate an encoded bit stream; and means for outputting the generated encoded bit stream and the capacity information. Encoding device. 10. The means for performing iterative transform coding includes: means for generating a first image block from the input image; and a plurality of second image blocks from a portion of the input image within a higher-determined search range. Means for generating the first image, means for converting the second image block by a preset operation, means for selecting the converted second image block most similar to the first image, Means for selecting a second image block corresponding to the converted second image block; and outputting code position information indicating the position of the selected second image block. 10. An encoding apparatus according to claim 9, further comprising: means for outputting a transformation parameter representing the image block. 11. A decoding method for generating a decoded image from a code representing a block of an image subjected to iterative transform coding, wherein capacity information indicating a maximum allowable memory capacity of an image memory is generated so as to decode the code. Outputting the generated capacity information; receiving the code including block position information indicating the position of the image block in the image, and receiving a conversion parameter indicating a predetermined conversion operation performed on the image block. Recursively transforming the image block identified by the block position according to the received transformation parameter using the image memory until a preset condition is satisfied. 12. A decoding apparatus for generating a decoded image from a code representing a block of an image subjected to iterative transform coding, wherein capacity information indicating a maximum allowable memory capacity of an image memory is generated so as to decode the code. Means for outputting the generated capacity information, means for receiving the code including the block position information indicating the position of the image block in the image, and means for receiving a conversion parameter representing a predetermined conversion operation applied to the image block; Means for recursively transforming the image block identified by the block position according to the received transformation parameter using the image memory until a preset condition is satisfied. 13. A recording medium on which an encoding program for iteratively transform-encoding an image is recorded, the encoding program comprising: a step of storing an input image in a first image memory; Receiving capacity information indicating the maximum allowable memory capacity of the second image memory so as to perform transform decoding; determining a search range of the stored input image; and receiving the received information within the determined search range. Repetitively transform-encoding each of the blocks according to the obtained capacity information. 14. A recording medium storing an encoding program for iteratively transform-encoding an image, wherein the encoding program stores an input image in an image memory, and a maximum allowable memory capacity of the image memory. Generating capacity information indicating the following: and generating the coded bit stream by iteratively transforming each block of the image using the image memory; and generating the coded bit stream and the capacity information. And a step of outputting. 15. A recording medium on which a decoding program for generating a decoded image from a code representing a block of an iteratively-transformed coded image is recorded, wherein the decoding program stores an image in an image memory so as to decode the code. Generating capacity information indicating the maximum allowable memory capacity and outputting the generated capacity information; and receiving the code including block position information indicating the position of the image block in the image and applying the image block in advance. Receiving a conversion parameter representing a set conversion operation; and recursively converting the image block identified by the block position according to the received conversion parameter using the image memory until a preset condition is satisfied. And a recording medium.