JP2003244696A - Encoding processor, decoding processor, method therefor and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and method for enhancing compression ratio and image quality in encoding and decoding by an ADRC. <P>SOLUTION: In block splitting of an encoding object image by the ADRC, a resplit block is selected on the basis of the dynamic range of each block, a block size, and a difference in a dynamic range at re-splitting, and the selected re-split block is subjected to re-splitting. With this configuration, an optimum resplit block can be efficiently selected, and re-splitting can reduce the dynamic range of each block and the width of a quantization step to realize reduction of quantization errors and image quality enhancement. A block with a small dynamic range is selected, and thinning of pixels in the block is conducted to reduce the data amount of encoded data. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

The present invention relates to a coding processing device,
The present invention relates to a decoding processing device and method, and a computer program. More specifically, encoding using ADRC as a compression process of a block-divided image signal,
The present invention relates to an improved encoding processing device, decoding processing device and method, and computer program in a decoding process.

[0002]

2. Description of the Related Art An image signal is often subjected to an encoding process for the purpose of reducing the amount of information in recording process on a recording medium, data transfer process and the like. As one of the high-efficiency encoding processes for digital image signals, ADRC (Adaptive
Dynamic Range Coding) is known.

ADRC is disclosed in, for example, JP-A-61-1449.
As disclosed in No. 89, the image area is divided into blocks, and the maximum value (MAX) and the minimum value (MI) as the pixel values of a plurality of pixels included in the divided blocks.
N) dynamic range (D)
R) is calculated and an encoding process adapted to the calculated dynamic range (DR) is performed, which is a dynamic range adaptive compression method.

Regarding image encoding processing by ADRC,
It will be described with reference to the drawings. FIG. 18 shows ADR of image data.
It is a figure explaining the block division in the encoding process by C, and the calculation process of a dynamic range. For example, an image signal of one frame of moving image data is divided into blocks of a plurality of pixel areas, and the maximum value and the minimum value of the signal level of pixels included in each block are detected.

The pixel signal level is, for example, a brightness signal level when the image signal is black and white, and for example, brightness level data of 256 gradations of 0 to 255 is applied. When a YUV signal is used in the color image signal, that is, a luminance signal Y relating to luminance and two color signals U and V relating to colors are used, the maximum value and the minimum value are detected for each of Y, U and V, and the respective values are detected. Quantization of each signal, that is, encoding processing is performed. When applying color signals such as RGB, the maximum value and the minimum value are detected for each of RGB, and the quantization processing is performed for each signal.

The signal level of pixels in a block divided into small areas often has a value closer to the correlation of an image. Therefore, by defining the difference between the maximum value and the minimum value of the signal level in each block as the dynamic range in each block, redundancy in the signal level direction, that is, a level larger than the maximum signal level value in the block and Levels smaller than the minimum signal level value can be removed, enabling efficient quantization within the limited dynamic range within each block.

For example, as shown in FIG. 18, image data 80
1 is divided into a plurality of blocks. Next, the signal level of the pixel included in each block is detected, and the signal level data in the block is acquired. For example, the signal level of the pixel included in the block 802 is the signal level data 803.
Is obtained as. Next, the maximum value (MAX) and the minimum value (MIN) of the signal levels of the pixels included in the block are selected, and the difference between them is used as the dynamic range (DR).

The value of the pixel in the block is quantized based on the dynamic range (DR). The quantization process will be described with reference to FIG. The number of quantization bits is n
, The minimum value (MI
N) is subtracted, the subtracted value is divided by DR / 2 ⁿ , and the code corresponding to the divided value is set as the quantization code (Q code).

In the example of FIG. 19, block A and block B
2 shows an example in the case of n = 1, that is, 1-bit quantization. It is assumed that each block includes 8 pixels and the signal level of each pixel is distributed as shown in the figure. Dynamic range of block A (D
R) is determined by the maximum value and the minimum value of the pixels included in the block A, and the dynamic range (D
R) is determined by the maximum value and the minimum value of the pixels included in the block B.

In the case of 1-bit quantization, the dynamic range is divided into two, for example, the upper part is [1] and the lower part is [0].
Is quantized according to the signal level of each pixel. As a result, the quantization code of block A is [1111100
1] and the quantization code (Q code) of the block B is configured by [00001111]. For example, in the case of 2-bit quantization, [0
4 values of 0], [01], [10], and [11] can be set, the dynamic range is divided into 2 ² = 4, and one of the quantization codes (Q code) is assigned to each pixel. become. In the case of 3-bit quantization, 2 ³ = 8
It will be divided.

FIG. 20 is a diagram showing a configuration of block information of each block when ADRC encoding processing is performed. The block information includes the minimum signal level (MIN) of pixels included in each block and the dynamic range (D
R) and the quantization code (Q
Code) is included. For example, when the signal level is 0 to 255, the minimum value (MIN) is 8 bits, the dynamic range (DR) is 8 bits, and the quantization code (Q code).
Can be configured as k × n bits. However,
n is the number of quantization bits, and k is the number of pixels in the block.

FIG. 21 shows the procedure of the encoding process and the decoding process by ADRC.

In the ADRC encoding process, step S80
1, the image data is divided into blocks, and step S8
In 02, the maximum value (MAX) and the minimum value (MIN) in the block are detected. Next, in step S803, the dynamic range (DR) in each divided block is calculated, and in step S804, the pixel value-minimum value (MI) of each block.
N) is calculated, and in step S805, quantization of each pixel value is performed based on a predetermined number of quantization bits = n, and in step S806, a minimum value (MIN), a dynamic range (DR), Quantization code (Q code)
Block information (see FIG. 20) is generated.

Generation of a quantized code (Q code) by a specific ADRC process is executed according to the following equation.

[0015]

## EQU1 ## DR = MAX-MIN + 1 Δ = DR / 2 ⁿ Q = (x-MIN + 0.5) / Δ (when DR ≧ 2 ⁿ ) Q = (x-MIN) (when DR <2 ⁿ )

In the above equation, DR: dynamic range, MAX: maximum value, MIN: minimum value, Q: quantization code (Q code), x: pixel value, Δ: quantization step width,
n: the number of quantization bits. In the calculation of the quantization code: Q when DR <2 ⁿ , Δ: pixel value of each block-minimum value (x-MIN) itself is applied as the quantization code without division by the quantization step width. To do. This is because the value itself of (x-MIN) can be expressed as a code of n bits or less. Also, DR = MA
[+1] in X-MIN + 1 is a process for setting DR = 1 when MAX = MIN.

On the other hand, the procedure of the decoding process based on the block information generated by the ADRC encoding will be described with reference to FIG. In the decoding process, in step S811, block information including a minimum value (MIN), a dynamic range (DR), and a quantization code (Q code) is acquired.

In step S812, a decoding process based on the block information is executed. The specific process of the decoding process is as follows, where the restored pixel value is x ′.
It is shown as an x ′ calculation formula.

[0019]

X ′ = (Q + 0.5) × Δ + MIN (when DR ≧ 2 ⁿ ) x ′ = (Q + MIN) (when DR <2 ⁿ )

In the above equation, x ': restored pixel value, MI
N: minimum value, Q: quantization code (Q code), Δ: quantization step width, n: number of quantization bits.

In step S813, each pixel value is determined based on the pixel value x'calculated in the above equation, and image reproduction is executed.

As described above, as the pixel value, for example, when the image signal is black and white, the luminance signal level value is applied, and for the color image signal, the luminance signal Y relating to the luminance such as YUV and the color signal. The two color signals U and V relating to Y, U, and V are used as pixel values, and the encoding process and the decoding process for each of the Y, U, and V values are executed.

Quantization (coding) by the above-mentioned ADRC
The processing and decoding processing is an example in which the number of coding bits applied to the pixel values in each block is the same. For example, if the number of quantization bits: n = 1 is set, 1-bit quantization processing is performed in all blocks, and if the number of quantization bits: n = 2 is set, all blocks are set. It is a configuration example for performing 2-bit quantization processing.

However, if the number of quantization bits is made common in all blocks, the dynamic range (DR)
The same number of bits will be quantized in both the large block and the small block, and the quantization step width in the block with a large dynamic range will be large. And the restored pixel value may be large.

Therefore, a variable length ADRC has been devised which performs coding processing by making the number of quantization bits in a block having a large dynamic range (DR) different from the number of quantization bits in a block having a small dynamic range (DR). .

The basic idea of variable length ADRC is to increase the number of quantization bits in a block having a large dynamic range (DR) and decrease the number of quantization bits in a block having a small dynamic range (DR). The basic configuration is shown in Japanese Patent Laid-Open No. 62-128621.

Specifically, for example, the number of quantization bits in a block having a large dynamic range (DR) is 3
As a bit, processing such as setting the quantization bit number to 1 in a block having a small dynamic range (DR) is performed. By performing such processing, in a block with a small dynamic range (DR), quantization is performed with DR / 2 ¹ set to a quantization step width: Δ that divides the dynamic range into two. In a block with a large (DR), it is possible to perform quantization by setting a quantization step width: Δ that is divided into eight as DR / 2 ³ , and in a block with a large dynamic range (DR), a finer quantization step width. Since: Δ can be set, it is possible to reduce the error between the original pixel value and the pixel value after the decoding process.

FIG. 22 shows the procedure of the encoding process and the decoding process by the variable length ADRC.

In the variable length ADRC encoding process, the image data is divided into blocks in step S821, and the maximum value (MAX) in the block is divided in step S822.
Detect the minimum value (MIN). Then step S823.
Then, the dynamic range (DR) in each divided block is calculated, and in step S824, the number of quantization bits is determined based on the calculated dynamic range (DR).

The number of quantization bits is determined, for example, on the basis of the following conditional expression for setting the number of quantization bits. 0 ≦ DR <th ₁ → 0 bit th ₁ ≦ DR <th ₂ → 1 bit th ₂ ≦ DR <th ₃ → 2 bit: th _n ≦ DR ≦ th _{n + 1} → n bit

In the above conditional expression, DR is each block
Is the dynamic range of th ₁~ Th_nIs predetermined
This is the set threshold. Ie dynamic range
The larger the (DR), the more bits are quantized
The dynamic range (D
Quantization step width in a block with large R): Δ
It prevents it from becoming too large.

Dynamic range (DR) of each block
When the number of quantized bits based on is determined, next, in step S825, the pixel value of each block minus the minimum value (MIN).
Is calculated, and in step S826, step S82
Quantization of each pixel value is performed based on the number of quantization bits = 0 to n determined in step 4, and in step S827, from the minimum value (MIN), the dynamic range (DR), and the quantization code (Q code). Block information (see FIG. 20) is generated.

On the other hand, the procedure of the decoding process based on the block information generated by the variable length ADRC encoding will be described with reference to FIG. In the decoding process, in step S831, block information including a minimum value (MIN), a dynamic range (DR), and a quantization code (Q code) is acquired.

In step S832, the number of quantization bits is calculated based on the dynamic range (DR) of each block acquired from the block information. Even on the decryption side,
The above-described quantization bit number setting conditional expression is held or acquired from the encoding processing device, and the quantization bit number is calculated based on the quantization bit number setting conditional expression.

Next, in step S833, decoding processing based on the block information is executed, and in step S834, each pixel value is determined based on the pixel value x'calculated by decoding and image reproduction is executed. To do.

Further, regarding a configuration in which the block size is changed according to the dynamic range, for example, Japanese Patent Publication No.
No. 21864. The technique disclosed in this publication measures a dynamic range in a first block set as a predetermined size area, defines a second block having a size different from that of the first block in accordance with the measured dynamic range, and defines ADRC in each block. Is applied to perform encoding.

The procedure of the encoding process described in this publication will be described with reference to FIG. In step S901, the image to be encoded is divided into blocks of a predetermined size. This is the first block.

Next, in step S902, processing blocks are sequentially selected, and in step S903, the dynamic range (DR) is calculated based on the maximum and minimum pixel values in the selected block. Step S904
Then, the calculated dynamic range is compared with a predetermined threshold value, and if the dynamic range is larger than the threshold value,
Proceeding to step S905, the first block is divided into smaller second blocks.

In step S906, ADRC encoding is performed based on the pixel value in the block. That is, the block information including the minimum value, the dynamic range, and the Q code is generated. In step S907, it is determined whether or not all blocks have been processed. If not, steps S902 and subsequent steps are repeated for unprocessed blocks.

By following this processing procedure, a block having a large dynamic range is redivided in the first block size initially set, and the ADRC encoding is executed in the second block size. The occurrence of an error due to an excessive step width is suppressed.

[0041]

However, in the process involving the change of the block size described in Japanese Patent Publication No. 8-21864 mentioned above, first, the process standard of how to set the first block size is set. However, there is a problem in that it is necessary to set the first block size in consideration of various factors such as image size and compression rate. In addition, a dynamic range threshold setting process to which the second block size should be applied is also required.
The optimum threshold differs depending on the image and the compression ratio of the encoded data to be output, and it has not been easy to set the optimum threshold.

The present invention has been made in view of the above problems, and in ADRC encoding and decoding processing by block division, processing applying various block sizes can be efficiently executed and various processing can be performed. The present invention provides an encoding processing device, a decoding processing device, and a method, and a computer program that realizes an encoding process that enables encoding and decoding based on optimal block division according to image data.

[0043]

The first aspect of the present invention is as follows.
A coding processing device for executing coding processing of image data, comprising block dividing means for setting divided pixel areas forming an image as a block, and a block unit set in the block dividing means for each block. Quantization processing means for executing quantization processing based on a set dynamic range, wherein the block division means selects, in order from a block having a large dynamic range, blocks having already been set, and re-divides the selected block. In the encoding processing device, the block setting process is performed by

Further, in an embodiment of the encoding processing device of the present invention, the block dividing means has the following determination conditions (1) to (3) and (1) a large dynamic range:
Regarding the determination conditions of (2) the block size is large, and (3) the difference between the dynamic range in the block before the subdivision and the maximum dynamic range of the block after the subdivision is large, the determination conditions (1), (2) ) And (3) are executed in the order of priority, and a process for selecting a re-division processing target block is executed.

Further, in an embodiment of the encoding processing device of the present invention, the block dividing means divides the image to be encoded into four parts, and the four divided blocks are used as initial setting blocks, and the judgment condition (1), The configuration is characterized in that the determination processing is executed in the priority order of (2) and (3), and the processing for selecting the re-division processing target block is executed.

Further, in an embodiment of the encoding processing device of the present invention, the encoding processing device further has a thinning processing means, and the thinning processing means thins the pixels in the block in a check pattern. And the quantization processing means is configured to execute the quantization processing for the residual pixels after the thinning processing of the thinning processing means.

Further, in one embodiment of the encoding processing device of the present invention, the encoding processing device further has a thinning processing means, and the thinning processing means has a dynamic range of a block equal to or less than a predetermined threshold value. It is characterized in that a thinning process for thinning out pixels in the block is executed for each block.

Further, in an embodiment of the encoding processing device of the present invention, the block dividing means has a configuration for executing a re-division target block selecting process based on a planned compression ratio, and is calculated from the planned compression ratio. Based on the allowable data amount as encoded data and the data amount increased by the re-division processing, the re-division processing block allowable number is calculated, and based on the calculated number, blocks with a large dynamic range are sequentially re-divided. It is characterized in that it is selected as a block.

Further, in an embodiment of the encoding processing device of the present invention, the quantization processing applied by the quantization processing means executes processing based on ADRC (Adaptive Dynamic Range Coding), and It is characterized in that it is configured to execute a process of calculating a quantization code (Q code) based on the set minimum pixel value (MIN) of each block and the dynamic range (DR).

Further, in an embodiment of the encoding processing device of the present invention, the encoding processing device is configured such that the minimum value (MIN) of pixel values of each block, the dynamic range (DR), and the quantization code (Q code). ) And block division information indicating the block position set by the block dividing means, the encoded data is output.

Further, in one embodiment of the encoding processing device of the present invention, the encoding processing device is configured such that the minimum value (MIN) of pixel values of each block, the dynamic range (DR), and the quantization code (Q code). It is characterized in that it is configured to output coded data having block information consisting of (4) and additional information indicating whether or not to execute pixel thinning in each block.

Further, in one embodiment of the encoding processing device of the present invention, the encoding processing device is configured such that the minimum value (MIN) of pixel values of each block, the dynamic range (DR), and the quantization code (Q code). It is characterized in that it is configured to output encoded data having block information consisting of (1) and additional information indicating whether the block is a subdivided block.

Further, a second aspect of the present invention is a decoding processing device for executing a decoding process of coded image data, which is a minimum value (MIN) stored in block information as coded data of each block unit. , Dynamic range (DR), and decoding processing means for executing pixel value decoding processing for each block based on a quantization code corresponding to each pixel, and block re-division information stored in the encoded data. A block reconstruction unit that identifies the position of the restored block based on the above and executes block reconstruction.

Further, in one embodiment of the decoding processing device of the present invention, the decoding processing applied by the decoding processing means is:
It is a dequantization process corresponding to ADRC (Adaptive Dynamic Range Coding), and is configured to execute a process of calculating a restored pixel value based on a minimum value (MIN) corresponding to the block and a dynamic range (DR). It is characterized by

Further, in one embodiment of the decoding processing device of the present invention, in the decoding processing device, the quantization code stored in the block information is thinned out instead of data corresponding to all pixels in the block. It has a thinned-out data restoration means for executing thinned-out data restoration processing in the case of data, and the thinned-out data restoration means is an average value of a plurality of restored pixel values decoded by the decoding processing means based on a quantization code, It is characterized in that it is configured to execute a process of setting as a pixel value of thinned pixel data.

Further, a third aspect of the present invention is a coding processing method for executing coding processing of image data, which comprises a block dividing step of setting divided pixel areas forming an image as a block, and the block dividing. A block unit set in the step, a quantization process step of performing a quantization process based on a dynamic range set corresponding to the block, and the block division step, for the set block, dynamic An encoding processing method is characterized in that blocks are selected in order from a large range and block setting processing is performed by re-dividing the selected block.

Further, a fourth aspect of the present invention is a decoding processing method for executing decoding processing of coded image data, which is a minimum value (MIN) stored in block information as coded data in each block unit. , A dynamic range (DR), and a decoding process step of executing a pixel value decoding process for each block based on a quantization code corresponding to each pixel, and block re-division information stored in the encoded data. And a block reconstruction step of executing block reconstruction by identifying the position of the restored block based on the above.

Further, a fifth aspect of the present invention is a computer program as an execution program of an encoding process for executing an encoding process of image data, wherein divided pixel areas forming an image are set as blocks. A block division step, and a quantization processing step that executes a quantization process based on a dynamic range set corresponding to the block in block units set in the block division step. Furthermore, the computer program is characterized by further comprising the step of selecting blocks having a large dynamic range in order with respect to already set blocks and performing block setting processing by re-dividing the selected block.

Further, a sixth aspect of the present invention is a computer program as an execution program of a decoding process for executing a decoding process of coded image data, wherein block information as coded data of each block unit is obtained. Stored minimum value (MIN) and dynamic range (D
R), and a decoding processing step for executing pixel value decoding processing for each block based on the quantization code corresponding to each pixel, and a restoration block based on the block re-division information stored in the encoded data. Identify the location of
A block reconstruction step for performing block reconstruction,
And a computer program characterized by having.

Further, a seventh aspect of the present invention is a program recording medium for providing a computer program for causing an image data encoding process to be executed on a computer system, wherein the computer program constitutes an image. A block division step of setting the divided pixel area to be a block, a quantization processing step of executing a quantization process based on a dynamic range set corresponding to the block in the block unit set in the block division step, The block dividing step further includes a step of selecting blocks having a large dynamic range in order from already set blocks and performing block setting processing by re-dividing the selected block. It is on the program recording medium.

Further, an eighth aspect of the present invention is a program recording medium for providing a computer program for causing a decoding process of coded image data to be executed on a computer system, wherein the computer program is each block. Pixel value decoding processing for each block is executed based on the minimum value (MIN) and dynamic range (DR) stored in the block information as encoded data of each unit, and the quantization code corresponding to each pixel. A program comprising: a decoding processing step; and a block reconstruction step of identifying a position of a restored block based on the block re-division information stored in the encoded data and executing block reconstruction. It is on the recording medium.

[0062]

The present invention does not fix the block size of the encoding process or the decoding process by ADRC, but determines the subdivided block based on the difference of the dynamic range of each block, the block size, and the dynamic range when subdivided. It is a configuration to select, it becomes possible to efficiently select the optimal subdivision block, the dynamic range of each block is reduced by the repartition processing, the quantization step width is reduced, the quantization error is reduced, Improvement of image quality is realized.

Further, according to the present invention, a block having a small dynamic range is selected and the thinning process of check pixels in the block is executed, thereby reducing the data amount of the encoded data and improving the compression rate. Made possible
Since the selection of blocks to be thinned out is determined based on the dynamic range of each block, efficient processing is possible and good image quality can be maintained.

The computer program of the present invention is, for example, a storage medium or communication medium provided in a computer-readable format for a general-purpose computer system capable of executing various program codes, such as a CD or FD. , MO, etc., or a computer program that can be provided by a communication medium such as a network. By providing such a program in a computer-readable format, processing according to the program is realized on the computer system.

Further objects, features and advantages of the present invention are as follows.
A more detailed description will be made clear based on embodiments of the present invention described below and the accompanying drawings. In this specification, the system is a logical set configuration of a plurality of devices, and is not limited to a device in which each configuration is provided in the same housing.

[0066]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an encoding processing device of the present invention,
The decoding processing device and method will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of the encoding processing device of the present invention. The configuration of the encoding processing device shown in FIG. 1 will be described. The image data to be encoded is first input to the block division unit 101, and the image region to be encoded is divided into blocks.

A mode of block division processing in the encoding processing apparatus of the present invention will be described with reference to FIG. When the image to be encoded is the image shown in (a), the block division unit 101 first divides the entire image into four as shown in (b) and executes the first block division process.
Next, as shown in (c), the dynamic range (DR) of each block is obtained based on the pixel value in the divided block. In the illustrated example, the dynamic range of each of the four blocks is 170, 213, 130, and 175.

Further, the block dividing unit 101 (d)
As shown in, the block having the largest dynamic range (DR) value in each block is selected. in this case,
The maximum dynamic range (DR) is a block with a DR value of 213. The block division unit 101 uses (e)
As shown in, the block having the DR value of 213 is further divided into four. Further, as shown in (f), the dynamic range (DR) of each block is obtained based on the pixel value in the divided block. In the illustrated example, the dynamic range of the first divided block is 170, 130, 175.
In this case, the dynamic range of the blocks generated by the re-division processing is 160, 78, 128, 59.

The block division unit repeatedly executes such block division processing until the predetermined maximum number of blocks is reached, and performs block setting processing.

The detailed structure of the block division unit 101 is shown in FIG. The block division unit 101 is a block division processing unit 1.
21, the DR, the block size determination processing unit 122, and the subdivision block selection unit 123, and the block division processing unit 12
1, the DR / block size determination processing unit 122 determines the dynamic range and block size in the divided block, and the re-divided block selection unit 123 selects the block having the maximum DR value as the re-divided block. The block division processing unit 121 divides the selected block. These processes are repeatedly executed.

FIG. 4 shows a flowchart of the block division processing executed by the block division unit 101. Step S1
In 01, as initialization processing, the number of blocks = 1 and the number of divisions = 0 are set. In step S102, the entire image to be encoded is set as a block of interest. This is a process in which the entire image to be encoded is regarded as one block, and corresponds to the state of FIG.

In step S103, the target block is set to 4
To divide. This corresponds to the state shown in FIG. In step S104, the dynamic range (DR) of each block in the divided blocks is calculated. This process
It is performed based on the analysis of the pixel value of the pixel included in each block. It should be noted that the pixel value is, for example, the brightness signal level when the image signal is black and white, and is the brightness level data of 256 gradations of 0 to 255, for example. When a YUV signal is used in the color image signal, that is, a luminance signal Y relating to luminance and two color signals U and V relating to colors are used, the signal levels are for Y, U and V, respectively.
When a color signal such as RGB is applied, the signal level is for each of RGB. Block division processing and further quantization processing will be executed for each signal, but since the processing mode is the same, in the following,
The description will be made assuming that the processing is performed on the brightness level signals of 256 gradations of 0 to 255.

When the dynamic range (DR) of each block in the divided blocks is calculated in step S104, the block list is generated or updated based on the calculated DR value in step S105.

FIG. 5 shows an example of the structure of the block list. As shown in FIG. 5, the block list includes a dynamic range value [DR value] in each divided block, a coordinate value as position data at the upper left end of the block, a block size (x × y), and further subdivision. The difference data with the current DR value in that case, that is, the difference data with the value of the dynamic range of the current block and the maximum value of the dynamic range when the current block is subdivided into four are stored.

In step S105, when a new block is generated, a process of adding these data to the block list is performed.

In step S106, the process of determining the block of interest, that is, the block to be subdivided is executed based on the block list. Details of this processing will be described with reference to the flow of FIG.

In the setting process of the block of interest, in step S201, the minimum block size is first designated as the initialization process. The limit value of the minimum block size is 1 pixel, but in the case of ADRC encoding processing, the minimum value (MIN), dynamic range (DR), and quantization code (Q code) for each block are generated. If the minimum block size is set to be small, a lot of block information will be generated, and the data amount as a whole will be increased. However, the smaller the minimum block size, the more the quantization error can be suppressed. Therefore, the minimum block size is set according to the required compression rate of output data and the allowable image quality.

Next, in step S202, the block list is read. The block list has the data structure shown in FIG. In step S203, the entire entry of the block list is selected as a candidate for selection as a block of interest to be subdivided. Step S20
In 4, the maximum dynamic range (D
Select the block with R).

In step S205, it is determined whether or not the division size of the selected block ≦ minimum block size, and if Yes, the block is excluded from the candidate blocks in step S206, and further,
In step S204, a candidate block is selected from the selection candidates after exclusion.

When the candidate block is selected through the processing of steps S204 to S206, it is determined in step S207 whether there are a plurality of blocks having a DR value equal to the dynamic range (DR) of the candidate block.

For example, in the block list example shown in FIG. 5, the dynamic range of the three blocks (b), (c), and (d) is equal to 53. In such a case, subdivision from these plural blocks is performed. It is necessary to select one block to execute the process.

This processing is performed in steps S208 to S210.
It is executed as the process of. In step S208, the block having the largest block size is selected from the same DR value blocks. When there are blocks having the same DR value and the same size (Yes in step S209), the process of selecting the block having the maximum difference between the DR value of the current block and the DR value after the division is executed in step S210. To do.

The processing of steps S208 to S210 will be described with reference to the example of the block list of FIG. In the process in step S208, for example, the block having the largest block size is selected from (b) to (d) in the list of FIG. 5, and (b) and (c) are selected. Further, as the process of step S210, from (b) and (c) in the list of FIG. 5, a block in which the difference between the DR value of the current block and the DR value after division is the maximum is (b).
Is selected.

As described above, the determination processes of (1) the maximum dynamic range, (2) the block size is large, and (3) the DR value difference is large are sequentially executed, and one block is selected as the re-division processing target block. Is selected. In addition, also in these processes, when a plurality of blocks are selected as candidates, a process such as selecting only one from the top of the list may be executed.

In step S211, one selected candidate block is determined as a target block, that is, a subdivision processing target block.

Returning to the processing flow of FIG. 4, the description of the block division processing will be continued. Step S described with reference to FIG.
When the process of determining the block of interest in 106 is completed, the process proceeds to step S107, and it is determined whether the current block number + 3 ≦ the set maximum block number.

The number of current blocks + 3 indicates the number of blocks when a new subdivision process is executed, and the number of blocks when the subdivision is performed is equal to or less than the preset maximum number of blocks as a predetermined upper limit number of blocks. Only in the case of, the processing of step S104 and thereafter, that is, the re-division processing of the target block is executed. When the number of blocks when the redivision is performed exceeds the predetermined upper limit number of blocks, a new redivision process is not performed and the block division process is terminated.

As described above, in the block division processing of the present invention, the block subdivision is executed within the range that does not exceed the predetermined number of blocks, and the subdivision target block has (1) the dynamic range as described above. Maximum, (2)
The block size is large, and (3) the DR value difference is selected according to the judgment condition.

FIG. 7 shows a flow for explaining the procedure of the encoding processing of the encoding processing device (encoder) of the present invention. Each step will be described with reference to the configuration of the encoding processing device in FIG.

In step S301, the block division unit 101 executes block division. As described above, the block division includes the re-division processing, and the re-division processing target block is selected and executed based on the DR value, the block size, and the DR value difference up to a predetermined number of blocks. Processing.

Next, in step S302, blocks to be processed are sequentially selected. In step S303, the pixel value analysis of the processing target block is executed, and the values such as the minimum value, the maximum value, and the dynamic range are acquired.

Further, in step S304, it is determined whether or not the thinning-out process is executed, and when the thinning-out process is executed, the thinning-out processing unit 104 performs the thinning-out process. The thinning-out processing unit 104 executes thinning-out processing on the assumption that a predetermined pixel value is restored from other pixel data. This thinning-out process will be described later.

When executing the thinning-out process, step S
If the thinning process is not executed after the thinning process of 305, step S305 is omitted and the quantization process in step S306 is executed.

In step S306, the quantization process is executed. In the configuration of FIG. 1, DR, minimum value (MI
N) The detection unit 102 calculates the dynamic range (DR) and the minimum value (MIN) based on the pixel value in the processing target block, and the quantization (encoding) processing unit 103.
, Dynamic range (DR), and minimum value (MI
A quantization code (Q code) is calculated based on N) and the pixel value of each pixel. Quantization (encoding) processing unit 10
Quantization code (Q code) calculation executed in 3 is
It is executed as a process according to the following formula.

[0096]

## EQU3 ## Δ = DR / 2 ⁿ Q = (x−MIN + 0.5) / Δ (when DR ≧ 2 ⁿ ) Q = (x−MIN) (when DR <2 ⁿ ) (Equation a1)

In the above equation, x is the pixel value, Δ is the quantization step width, and n is the number of quantization bits. DR is a dynamic range (DR) corresponding to each block,
The information acquired by the DR / minimum value (MIN) calculation unit 102 is applied based on the pixel value in each block. MI
N is the minimum value (MIN) corresponding to each block,
The information acquired based on the pixel value in each block is also applied to this.

Further, when executing the processing to which the variable length ADRC is applied, the dynamic range (D
R), the quantization code (Q code) of each pixel by the quantization processing according to the number of quantization bits set in advance.
Will be set. The number of quantized bits in the case of the variable length ADRC is determined, for example, based on a predetermined quantized bit number setting conditional expression below.

[Formula 4] 0 ≦ DR <th ₁ → 0 bit th ₁ ≦ DR <th ₂ → 1 bit th ₂ ≦ DR <th ₃ → 2 bit: th _n ≦ DR ≦ th _{n + 1} → n bit. a2)

In the above conditional expression (expression a2), DR
Is the dynamic range of each block, and in the case of the present embodiment, is the dynamic range (DR) calculated based on the pixel value detected by the DR and minimum value (MIN) detection unit 102. th ₁ to TH _n is a predetermined threshold.

Each block in the case of variable length ADRC and an example of the configuration of the quantization bit will be described with reference to FIG.

The image data shown in FIG. 8A to be quantized is divided into blocks by the block division unit 101, and the dynamic range (D
R) and the minimum value (MIN) are detected by the DR and minimum value (MIN) detection unit 102, and the quantization (encoding) processing unit 1
03 sets the number of quantization bits according to the dynamic range of each block and performs the quantization process. The setting process of the number of quantization bits is performed by comparing the dynamic range in a block with a threshold value, as shown in (Formula a2) above.

FIG. 8B shows an example of the quantization code (Q code) of each block. In this example, the block 1 is 4-bit quantization, and the block p is 3-bit quantization. , Block s has been subjected to 4-bit quantization processing. The number of quantization codes in each block is the number of pixels in the block: m × n = k, and the total number of bits of the quantization codes included in each block is block 1
Is 4 × k bits, the block p is 3 × k bits, and the block s is 4 × k bits.

The quantized code (Q code) generated by the quantization processing unit 103 is stored in the block information for each block, and in step S307, the encoded data including the block information is output or stored in the storage means. Is
The encoding process ends.

FIG. 9 shows an example of the configuration of encoded data when the thinning process is not executed. As shown in FIG. 9, the encoded data is composed of image information, block division information, and block information. The block information includes the minimum value (MIN) and dynamic range (D) in each block.
R) and the quantization code (Q code).

The image information includes image format, image size,
It is additional information including information such as the number of quantization bits. The block division information is data indicating the block division mode executed by the block division unit. The format of the block division information will be described with reference to FIG.

The block division information is used for determining in which position of the image information the decoded data based on the block information is the coded data in the decoding processing device that receives the coded data and executes the decoding process. Information. That is, it is used to determine which position each block information corresponds to image data.

The block division information is represented by 1 bit for a block having a division (child) as [1] and a block having no division (child) as [0]. It is configured as sequence data generated when the data is arranged in a tree shape downward.

The image shown in FIG. 10 is divided block a,
Of b, c, and d, the only block with further division is b, the block b is [1], and the blocks a, c, and d are [0].
Is set. The whole block has divisions (children), so it is set as [1], and the subdivided blocks ba, bb, bc, and bd of the block [b] have no further divisions (children), so are set to [0]. It The block division information [101000000] is generated by arranging these pieces of data in the top-left order. On the decoding processing side, it becomes possible to specify the pixel position of the decoded data based on the block information in association with this block division information.

After the block division information, as shown in FIG. 9, a number of pieces of block information corresponding to the number of blocks are stored. The block information is the minimum value (MI
N), dynamic range (DR), quantization code (Q
Code).

The block division information is added to the encoded data generated by the encoding processing device of the present invention. This is the amount of data indicating the tree structure, and the number of bits is represented by the following formula. Tree structure display bit number = (final block number without children-1) / 3 × 4 + 1) × 1 bit

The increase in the number of bits calculated by the above equation does not increase the compression rate because the ratio of the encoded data to the total number of bits is extremely small.

Next, the thinning-out processing executed by the thinning-out processing unit 104 in the block diagram of the encoding processing apparatus of FIG. 1 will be described.

FIG. 11 is a diagram for explaining an example of thinning processing performed by the thinning processing unit 104 in the encoding processing device of the present invention.

FIG. 11 (a) shows a plurality of pixels in a certain divided block. The thinning-out process is, as shown in (b),
Pixels selected in a check pattern except for the pixels around the boundary of the block are set as the thinning target pixels. This is a procedure for enabling restoration processing of thinned pixels to be executed based on the upper and lower pixel values and the left and right pixel values as shown in (c). The restoration of the pixel values of the thinned pixels is set, for example, as an average value of four pixels above and below and left and right of the thinned pixels.

On the encoding processing device side, when executing the thinning processing, the thinning processing unit in the configuration of FIG.
As shown in FIG. 1 (b), after the pixels in the block are thinned out in a check pattern, the quantization processing unit 103 generates a quantization code (Q code) only for the pixel values remaining after the thinning out. The number of quantized codes is almost halved, and the amount of data is reduced.

The thinning process is executed for all the divided blocks. Or do not run at all. Alternatively, various processing forms are possible such as executing only for a specific divided block.

As an example of the mode in which the thinning-out process is executed only for a specific divided block, there is a method in which blocks having a small dynamic range are selected and the thinning-out process is executed only for these blocks.

A block with a small dynamic range is
This means that the difference between the pixel values contained in the block is small, and when the thinning processing is executed, the difference from the original pixel value can be reduced even if the pixel value interpolation processing based on other surrounding pixels is executed. It is based on the reason.

FIG. 12 shows a determination processing flow when the thinning processing is selectively executed. In step S401, a block to be subjected to determination processing is selected, and step S
In 402, the pixel value analysis of the pixels in the block is executed, and in step S403, it is determined whether or not the dynamic range (DR) of the block acquired by the pixel value analysis is larger than a preset threshold value (DRmin).

If DR> (DRmin), the thinning processing is not executed, and the process proceeds to the quantization processing step of step S405. If DR> (DRmin) is not satisfied, the thinning processing of step S404 is executed. Step S
The quantization processing of 405 is executed. Block information is generated based on the data after the quantization processing.

According to the processing of this flow, DR> (DRm
block information as the quantized data based on the thinned-out data is generated only when it is not in). Therefore, it is necessary to set additional information for each block information to determine whether the block information is based on the thinned-out data, to the decoding processing device that receives the block information and executes the decoding. Becomes The data structure of these will be described later.

Next, a description will be given of the process of executing the subdivision process of block division based on the planned compression rate. In the subdivision block selection processing with reference to FIG. 6 described above,
The processing example of selecting a re-divided block according to the determination conditions of (1) maximum dynamic range, (2) large block size, and (3) large DR value difference has been described below. A processing example of generating a divided block and then selecting a re-divided block based on the planned compression rate will be described with reference to the processing flow of FIG. 13.

Each step of the flow shown in FIG. 13 will be described. An image to be processed is input in step S501, and the input image is divided into primary blocks in step S502. This primary block division is executed according to a preset block size. Step S
At 503, dynamic range (DR) calculation of each block is executed.

In step S504, the dynamic range (DR) of each block is compared with the threshold value (DRmin) for determining whether or not to execute the thinning process.
The number of blocks subject to thinning processing is calculated.

In step S505, DRm as a dynamic range threshold value for determining whether or not to execute block subdivision processing based on a preset planned compression rate.
Calculate ax.

The DRmax determination process in step S505 will be described in detail with a specific example. Image to be processed, primary divided block size, subdivided block size, and thinning process execution determination threshold: DRmin
Is set as follows.

[0127] Image size: 704 (pixels) x 480 (pixels) Primary block size: 8 (pixels) x 8 (pixels) Subdivision block size: 4 (pixels) x 4 (pixels) DRmin: 35

It is assumed that the pixel value information of each pixel is 8-bit data. At this time, if the scheduled compression rate is 1/3, the scheduled information amount based on the scheduled compression rate is: Scheduled information amount = (704 × 480 × 8) / 3 = 901120 bits (b1).

On the other hand, assuming that 2-bit quantization is executed for each block information of the normal ADRC processing, the minimum value (MIN): 8-bit dynamic range: 8-bit quantization code: 8 × 8 × 2 = 128 The total number of bits: 142 bits (b2).

The total number of blocks is (704 × 480) / (8 × 8) = 5280 Therefore, all block information is 5280 × 128 = 675840 bits (b3) Becomes

The amount of information reduced by the thinning process is
If the number of thinned blocks = A, 1 block (8 × 8)
Since the number of thinned pixels = 18, the amount of thinned information = (2 × 18) × A (b4).

When the threshold value (DRmin) for determining whether or not to execute the thinning process is set to 35, it is assumed that the number of thinned blocks = A = 125 is calculated. Thinned-out information amount = (2 × 18) × 125 = 4500 bits (b5).

At this time, the coded data amount in the case where only the thinning is executed and the block re-division processing is not executed is as follows: coded data amount = (b3)-(b5) = 675840-4500 = 671340 bits. b6).

The difference between the value (b6) and (b1) as the planned information amount based on the planned compression rate is as follows: difference = (b1)-(b6) = 901120-671340 = 229780 bits (b7) Become.

On the other hand, the amount of information increased by reblocking (4 × 4) of one primary block (8 × 8) is the minimum value (MIN) for the block information of the reblock (4 × 4). : 8-bit dynamic range: 8-bit quantization code: 4 × 4 × 2 = 32-bit total: 48 bits (b8) Therefore, the increased information amount = 4 × (b8)-(b2) = (4 × 48) −142 = 50 bits (b9)

Based on the difference (b7) from the planned information amount (b1) based on the planned compression ratio and the information amount (b9) increased by the block re-division, the allowable number of re-divided blocks is The number of subdivided blocks = (b1) / (b9) = 229780/50 = 4595.6≈4595.

Based on the number of blocks, the dynamic range of each primary block is arranged from the largest one to 459.
The dynamic range of the fifth block is set as DRmax. For example, when this value is DR = 39,
Set as DRmax = 39.

The dynamic range threshold value (DRmax), which indicates whether or not to perform re-division, is set in accordance with the above processing. Returning to the processing flow of FIG. 13, the description will be continued.

In step S505, when DRmax is calculated according to the above-described processing, step S506
To the dynamic range (D
R) and a threshold for determining whether to execute thinning processing (DRmin)
When DR> threshold value (DRmin) is not satisfied, the process proceeds to step S507 and thinning processing is executed.

If DR> threshold value (DRmin),
In step S508, the dynamic range (DR) of the processing target block is compared with the dynamic range threshold (DRmax) of whether or not to perform subdivision,
If DR ≧ threshold value (DRmax), step S5
09 block re-division processing, for example, a primary division block (8 × 8) is re-divided into four (4 × 4) small blocks.

After that, the quantization process of step S510 is executed, and in step S511, it is determined whether all blocks have been processed. If there is an unprocessed block, the processes of step S506 and subsequent steps are repeatedly executed, and all blocks are processed. Performs quantization on blocks.

Next, with reference to FIG. 14, a process of generating the block list described above, comparing the dynamic ranges of the blocks, and sequentially dividing from the largest dynamic range (FIGS. 4 to 4). (See FIG. 6)
A process to which the thinning process described with reference to is added will be described.

In step S521, the number of blocks = 1 and the number of divisions = 0 are set as initialization processing. In step S522, the entire image to be encoded is set as a block of interest. This is a process in which the entire image to be encoded is regarded as one block.
Corresponding to the state of.

In step S523, the target block is set to 4
To divide. This corresponds to the state shown in FIG. In step S524, the dynamic range (DR) of each block in the divided blocks is calculated. This process
It is performed based on the analysis of the pixel value of the pixel included in each block.

In step S525, the dynamic range (DR) of each block is compared with the threshold value (DRmin) for determining whether or not to execute the thinning process.
The number of blocks subject to thinning processing is calculated.

In step S526, the dynamic range (DR) of the block to be processed is compared with the execution presence / absence determination threshold value (DRmin). If DR> threshold value (DRmin), the process advances to step S527 to perform thinning processing. Execute the process.

In step S528, when a new block is generated, a process of adding these data to the block list is performed. The configuration of the block list is the same as that described above with reference to FIG. 5, and the dynamic range value [DR value] in each divided block, the coordinate value as the position data of the upper left end of the block, the block size (x Xy), further, the difference data from the current DR value when the subdivision is executed, that is, the value of the dynamic range of the current block and the maximum value of the dynamic range when the current block is subdivided into four. Difference data is stored.

In step S529, the process of determining the target block, that is, the block to be re-divided is executed based on the block list. The details of this processing are the processing described above with reference to FIG. When the process of determining the target block in S529 according to the process flow shown in FIG. 6 is completed, the process proceeds to step S530, and it is determined whether the current block number + 1 the allowable block number.

In this process, the allowable number of re-divided blocks [allowable number of re-divided blocks = (b1) / (b9)] is calculated on the basis of the planned information amount based on the planned compression ratio and the information amount increased by the block re-division. , The number of re-divided blocks + 1, that is, the process of determining whether or not the number of re-divided blocks + 1 ≦ the allowable number of re-divided blocks is satisfied. Here, it is assumed that one block is divided into four as subdivision of the block.

If the number of re-divided blocks + 1 ≦ allowable number of re-divided blocks is satisfied, the processing from step S523 onward
That is, the redivision processing of the target block is executed. If the number of re-divided blocks + 1 ≦ allowable number of re-divided blocks is not satisfied, the process advances to step S531 to execute the quantization process based on the block-divided data.

According to the processing shown in FIG. 13 or FIG. 14, blocks that have undergone decimation processing, blocks that have not been executed, blocks that have been re-divided, and blocks that have not been re-divided are mixed. Block information for various blocks will be generated.

In the decoding processing device which performs decoding based on these mixed block information, it is necessary to determine these block information. In the encoding processing device, additional information is set in each block information for these discriminations.

FIG. 15 shows an example of the block information structure in which additional information is set. The block information includes the minimum value (MIN) of the signal level of the pixels included in each block, the dynamic range (DR), and the quantization code (Q code) calculated in the above processing. For example, the signal level is 0
In the case of ˜255, the minimum value (MIN) can be configured as 8 bits, the dynamic range (DR) can be configured as 8 bits, and the quantization code (Q code) can be configured as k × n bits. However, n is the number of quantization bits, and k is the number of pixels in the block. Further, the bit information indicating whether or not the thinning process is executed is 1 bit, for example, thinning process is present = [1],
None = [0], 1 bit of bit information indicating the presence / absence of re-division processing, re-division = [1], none =
Each information of [0] is set. The pixel position corresponding to the quantization code in the block information can be specified based on the block division information (see FIG. 9) in the header information described above, and whether or not the re-division processing is executed for each block information. It is not essential to add the bit information indicating the.

On the basis of the block division information or the additional information, it is possible to discriminate a block that has been subjected to thinning processing, a non-execution block, a block that has been further re-divided, and a block that has not been re-divided. It should be noted that if no re-division is performed, the bit information indicating the re-division can be omitted, and if no thinning processing is performed, the bit information indicating the presence or absence of the thinning can be omitted. Alternatively, any one bit information may be set as the additional information.

Next, regarding the configuration of the decoding processing device, FIG.
Will be described with reference to. The structure of the encoded data to be decoded has the structure shown in FIG. 16, and the image information including information such as the image format, the image size, and the number of quantization bits,
The block information is composed of block division information for discriminating at which position of the image information the decoded data based on the block information is the encoded data. The block information is data including a minimum value (MIN), a dynamic range (DR), and a quantization code (Q code) in each block, and is added to determine whether or not the subdivision processing is performed and whether or not the thinning processing is performed. Have information.

The coded data analysis unit 201 uses the image information,
The number of quantization bits and the position information of each block are acquired by referring to the block division information, and the block information for which the inverse quantization process is executed is sequentially analyzed. Further, it is determined from the block division information (see FIG. 9) in the header information or the additional information of each block information whether each block is a re-divided block or has been thinned out.

The minimum value acquisition unit 203 acquires the minimum value (MIN) from the block information. The DR acquisition unit 204
The dynamic range (DR) is acquired from the block information. The decoding (inverse quantization) processing unit 205 includes a quantization code (Q code) in the block information and a minimum value acquisition unit 203.
The decoding process is executed based on the acquired minimum value (MIN) and the dynamic range (DR) acquired by the DR acquisition unit 204. In the decoding process, the restored pixel value is x ′,
It is executed as a process of calculating x ′ according to the following formula.

[0158]

X ′ = (Q + 0.5) × Δ + MIN (when DR ≧ 2 ⁿ ) x ′ = (Q + MIN) (when DR <2 ⁿ ) (Equation a3)

In the above equation, x ': restored pixel value, MI
N: minimum value, Q: quantization code (Q code), Δ: quantization step width, n: quantization bit number, DR: dynamic range, and DR and MIN are dynamic range (obtained from block information). DR) and the minimum value (MIN).

In this way, the restored pixel value x'of each pixel is obtained based on the block information, and the image data is reproduced based on the restored pixel value.

However, when the thinning-out processing is being executed, the thinned-out data restoring unit 206 restores the thinned-out pixel data. Whether or not the thinning-out process is executed is performed by the block information analyzing unit 201 based on the additional information in the block information, and only in the case of the block information processing in which the thinned-out information is stored, the thinning-out data restoring unit 206 Execute the process.

The processing of the thinned-out data restoration unit is first described in FIG.
The process is as described with reference to, and the average value of the pixel values of the four pixels above and below and on the left and right of the thinned pixels is set as the pixel value of the thinned pixels.

In the case of the block information processing in which the thinned-out information is stored, the thinned-out data restoration unit 206 executes the thinned-out data restoration processing, and then the image reproduction and output based on the restored pixel value are executed.

The block reconstructing unit 207 executes the process of determining the block position and pixel position of the restored pixel, and the additional information stored in the encoded data as to whether or not the re-division is performed, and FIG. The process of determining the block position and pixel position of the restored pixel based on the block division information described with reference to FIG.

Next, the processing procedure of the decoding processing apparatus according to the present embodiment will be described with reference to the flowchart shown in FIG.

In step S601, encoded data including block information to be decoded is input. In step S602, the minimum value (MIN) and the dynamic range (DR) values set for each block are acquired from the input block information, and in step S603, the quantization code (Q) acquired from the block information is acquired. Code) and the minimum value (M
IN) and the dynamic range (DR), and the decoding process is executed. The decoding process is described above (formula a
This is executed as a process of calculating the restored pixel value x ′ according to 3).

Next, in step S604, it is determined whether or not the data has been thinned out. This is additional information in the block information (see FIGS. 15 and 16).
It is executed based on. If the block information has not been thinned out, the pixels decoded in the decoding processing in step S603 are all the pixels included in the block, and the flow advances to step S606.

If it is determined in step S604 that the thinning-out process is being executed based on the additional information in the block information, in step S605 the thinning-out data restoring unit executes the process of restoring the thinned-out pixel data. That is, the four pixels above and below and to the left and right of the thinned pixels
The average value of the pixel values of the pixels is set as the pixel value of the thinned pixel.

In step S606, the position of each block is determined based on the additional information indicating whether or not the redivision has been performed and the block division information described above with reference to FIG.
The position of the restored pixel is determined, and in step S607,
Output the pixel value in the block.

As described above, in the configuration of the present invention, AD
Since the block size is not fixed when performing the encoding by RC and the encoding is performed by performing the re-division processing, it is possible to reduce the blocks having a large dynamic range, and the encoding and decoding are performed. The difference between the restored pixel and the original pixel that accompanies it can be reduced, and the deterioration of the image quality can be prevented.

Further, in the configuration of the present invention, by executing the thinning-out process, the data amount of the encoded data can be reduced and the compression rate can be improved.

Further, since the selection of the subdivision processing target block and the selection of the thinning processing target block are made based on the dynamic range of each block, efficient processing is possible and good image quality is maintained. It becomes possible to do.

The present invention has been described in detail above with reference to the specific embodiments. However, it is obvious that those skilled in the art can modify or substitute the embodiments without departing from the scope of the present invention. That is, the present invention has been disclosed in the form of exemplification, and should not be limitedly interpreted. In order to determine the gist of the present invention, the section of the claims described at the beginning should be taken into consideration.

The series of processes described in the specification can be executed by hardware, software, or a combined configuration of both. When executing the processing by software, the program recording the processing sequence is installed in the memory in the computer incorporated in the dedicated hardware and executed, or the program is stored in a general-purpose computer capable of executing various processing. It can be installed and run.

For example, the program can be recorded in advance in a hard disk or a ROM (Read Only Memory) as a recording medium. Alternatively, the program may be a flexible disk or a CD-ROM (Compact Disc Read Only).
Memory), MO (Magneto optical) disk, DVD (Dig
Ital Versatile Disc), magnetic disk, semiconductor memory, or other removable recording medium can be temporarily (or permanently) stored (recorded). Such a removable recording medium can be provided as so-called package software.

The program is installed in the computer from the removable recording medium as described above, is wirelessly transferred from the download site to the computer, or is wired to the computer via a network such as LAN (Local Area Network) or the Internet. Then, the computer can receive the program thus transferred and install it in a recording medium such as a built-in hard disk.

The various processes described in the specification are
The processing may be executed not only in time series according to the description, but also in parallel or individually according to the processing capability of the device that executes the processing or the need.

[0178]

As described above, according to the configuration of the present invention, when the block size of the encoding process or the decoding process by ADRC is not fixed, the dynamic range of each block, the block size, and the re-division are performed. Since the re-divided block is selected based on the difference in the dynamic range of, it is possible to efficiently select the optimum re-divided block, and the re-division processing reduces the dynamic range of each block. It is possible to reduce the quantization step width, reduce the quantization error,
Improvement of image quality is realized.

Further, according to the configuration of the present invention, by selecting a block having a small dynamic range and executing the thinning process of the check-like pixels in the block,
The amount of encoded data can be reduced, and the compression rate can be improved. Since the block to be thinned out is selected based on the dynamic range of each block, efficient processing is possible and good image quality can be maintained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an encoding processing device of the present invention.

FIG. 2 is a diagram illustrating block division processing of the present invention.

FIG. 3 is a configuration diagram of a block division unit of the encoding processing device of the present invention.

FIG. 4 is a diagram showing a block division processing flow of the present invention.

FIG. 5 is a diagram showing a configuration example of a block list according to the configuration of the present invention.

FIG. 6 is a flowchart illustrating a process of determining a block of interest to be divided into blocks according to the present invention.

FIG. 7 is a flowchart illustrating processing in the encoding processing device of the present invention.

FIG. 8 is a variable length ADR in the encoding processing device of the present invention.
It is a figure which shows the quantization code generation process example of C encoding process.

FIG. 9 is a diagram showing an example of a coded data structure according to the structure of the present invention.

FIG. 10 is a diagram illustrating block division information in encoded data according to the configuration of the present invention.

FIG. 11 is a diagram illustrating thinning processing and restoration processing according to the present invention.

FIG. 12 is a flowchart illustrating a process of selecting a block to be thinned out according to the present invention.

FIG. 13 is a flowchart illustrating a thinning process and a redivision process target block selection process in the encoding process of the present invention.

FIG. 14 is a flowchart illustrating thinning processing and redivision processing target block selection processing in the encoding processing of the present invention.

FIG. 15 is a diagram showing an example of a coded data structure according to the structure of the present invention.

FIG. 16 is a block diagram showing a configuration example of a decoding processing device in the configuration of the present invention.

FIG. 17 is a flowchart illustrating a decoding processing procedure according to the configuration of the present invention.

FIG. 18 is a diagram illustrating an outline of ADRC processing.

FIG. 19 is a diagram illustrating an outline of quantization processing in ADRC processing.

FIG. 20 is a diagram illustrating a configuration of block information generated in ADRC processing.

FIG. 21 is a flowchart illustrating a procedure of fixed length ADRC processing.

FIG. 22 is a flowchart illustrating a procedure of variable length ADRC processing.

FIG. 23 is a flowchart illustrating a procedure of a conventional ADRC process involving block re-division processing.

[Explanation of symbols]

101 block division unit 102 DR, minimum value (MIN) detector 103 Quantization processing unit 104 Thinning processing unit 121 block division processing unit 122 DR, block size determination processing unit 123 Subdivision block selection unit 201 coded data analysis unit 203 Minimum value (MIN) acquisition unit 204 DR acquisition unit 205 Decoding (Dequantization) Processing Unit 206 Thinned-out data restoration unit 207 Block reconstruction unit 801 image data 802 blocks 803 Signal level data

Continued front page    (72) Inventor Yu Ikeda             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation (72) Inventor Tsutomu Ichikawa             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation (72) Inventor Masaaki Hattori             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation (72) Inventor Hiroto Kimura             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation (72) Inventor Fukushi Takeho             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation (72) Inventor Sakon Yamamoto             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation F-term (reference) 5C059 LB07 LC09 MA28 MC11 UA02                       UA05 UA39                 5J064 AA02 BB04 BB12 BC16 BC22                       BC25 BC27 BD01

Claims (19)

[Claims] 1. A coding processing device for executing coding processing of image data, comprising block dividing means for setting a divided pixel area forming an image as a block, and a block unit set in the block dividing means, Quantization processing means for executing a quantization process based on a dynamic range set corresponding to the block, and, the block dividing means, for the set block, sequentially from a block with a large dynamic range, An encoding processing device having a configuration for performing block setting processing by re-dividing a selected block. 2. The block division means has the following determination conditions (1) to (3), (1) a large dynamic range, (2) a large block size, and (3) a dynamic range in a block before subdivision. For each judgment condition that the difference from the maximum value of the dynamic range of the block after subdivision is large, the judgment conditions (1), (2),
The encoding processing apparatus according to claim 1, wherein the determination processing is executed in the priority order of (3), and processing for selecting a redivision processing target block is executed. 3. The block dividing means divides an image to be encoded into four, and sets the four divided blocks as an initial setting block, and the determination conditions (1), (2),
The encoding processing apparatus according to claim 2, wherein the determination processing is executed in the priority order of (3), and the processing for selecting a redivision processing target block is executed. 4. The encoding processing device further includes thinning processing means, the thinning processing means executes thinning processing for thinning pixels in a block in a check pattern, and the quantization processing means uses the thinning processing. The encoding processing apparatus according to claim 1, wherein the encoding processing apparatus is configured to execute a quantization processing for the residual pixels after the thinning processing of the processing means. 5. The encoding processing apparatus further comprises thinning processing means, wherein the thinning processing means thins out pixels in blocks in a check pattern for blocks whose dynamic range is equal to or less than a predetermined threshold value. The encoding processing device according to claim 1, wherein the encoding processing device is configured to execute processing. 6. The block dividing means has a configuration for executing a redivision target block selection process based on a planned compression ratio, an allowable data amount as encoded data calculated from the planned compression ratio, and a redivision. It is configured such that a permissible number of subdivision processing blocks is calculated based on the amount of data increased by processing, and blocks having a large dynamic range are sequentially selected as the subdivision target blocks based on the calculated number. The encoding processing device according to Item 1. 7. The quantization processing applied by the quantization processing means executes processing based on ADRC (Adaptive Dynamic Range Coding), and a minimum pixel value (MIN) of pixel values of each block set by the block dividing means. , And dynamic range (DR)
The encoding processing device according to claim 1, wherein the encoding processing device is configured to execute a process of calculating a quantized code (Q code) based on. 8. The encoding processing device sets block information including block information including a minimum value (MIN) of pixel values of each block, a dynamic range (DR), and a quantization code (Q code), and the block dividing means. 2. The configuration is such that encoded data having block division information indicating a selected block position is output.
The encoding processing device according to. 9. The encoding processing device comprises block information including a minimum value (MIN) of pixel values of each block, a dynamic range (DR), and a quantization code (Q code), and pixel thinning in each block. The coding processing device according to claim 1, wherein the coding data is configured to output coded data having additional information indicating whether or not to execute. 10. The encoding processing device re-divides a block from block information including a minimum pixel value (MIN) of each block, a dynamic range (DR), and a quantization code (Q code). The encoding processing device according to claim 1, wherein the encoding processing device is configured to output encoded data having additional information indicating whether the block is a block or not. 11. A decoding processing device for executing a decoding process of coded image data, comprising a minimum value (MIN) and a dynamic range (DR) stored in block information as coded data of each block. Decoding processing means for executing pixel value decoding processing for each block based on the quantization code corresponding to each pixel, and identifying the position of the restored block based on the block re-division information stored in the encoded data. Then
A block processing unit for executing block reconstruction, and a decoding processing device. 12. A decoding process applied by the decoding processing means is a dequantization process corresponding to ADRC (Adaptive Dynamic Range Coding), and a minimum value (MIN) and a dynamic range (DR) corresponding to the block are obtained. The decoding processing device according to claim 11, wherein the decoding processing device is configured to execute a process of calculating a restored pixel value based on the decoding pixel value. 13. The decoding processing device further executes decimation data restoration processing when the quantization code stored in the block information is not the data corresponding to all pixels in the block but decimation data. And a decimation data decompression unit, wherein the decimation data decompression unit executes a process of setting an average value of a plurality of decompression pixel values decoded by the decoding processing unit based on a quantization code as a pixel value of the decimation pixel data. The decoding processing device according to claim 11, wherein the decoding processing device has the following configuration. 14. A coding processing method for executing coding processing of image data, comprising a block dividing step of setting a divided pixel area forming an image as a block, and a block unit set in the block dividing step, Quantization processing step for executing a quantization process based on a dynamic range set corresponding to the block, and, the block division step, for the set block, select from a block with a large dynamic range in order, An encoding processing method characterized in that block setting processing is performed by re-dividing a selected block. 15. A decoding processing method for executing decoding processing of coded image data, comprising a minimum value (MIN) and a dynamic range (DR) stored in block information as coded data in units of blocks. A decoding processing step of executing pixel value decoding processing for each block based on the quantization code corresponding to each pixel, and identifying the position of the restored block based on the block re-division information stored in the encoded data And a block reconstructing step for executing block reconstructing, and a decoding processing method. 16. A computer program as an execution program of an encoding process for executing an encoding process of image data, the block dividing step of setting divided pixel regions forming an image as a block, and the block dividing step. In a block unit set in, a quantization processing step for performing a quantization process based on a dynamic range set corresponding to the block, and, the block division step, further, for the set block, A computer program comprising the steps of: selecting blocks in order of increasing dynamic range and performing block setting processing by re-dividing the selected block. 17. A computer program as an execution program of a decoding process for executing a decoding process of encoded image data, comprising a minimum value (MIN) stored in block information as encoded data of each block unit, And a dynamic range (DR), and a decoding processing step for executing pixel value decoding processing in each block based on a quantization code corresponding to each pixel, and a block re-division information stored in the encoded data. A block reconstructing step of identifying the position of the restored block based on the block and executing the block reconstructing, and a computer program. 18. A program recording medium for providing a computer program for causing an image data encoding process to be executed on a computer system, wherein the computer program sets a divided pixel area forming an image as a block. A block division step, and a quantization processing step that executes a quantization process based on a dynamic range set corresponding to the block in block units set in the block division step, wherein the block division step is Further, the program recording medium is characterized by further comprising a step of: selecting a set block in order from a block having a large dynamic range and performing block setting processing by re-dividing the selected block. 19. A program recording medium for providing a computer program for causing a decoding process of encoded image data to be executed on a computer system, wherein the computer program is block information as encoded data of each block unit. A decoding process step of executing a pixel value decoding process for each block based on a minimum value (MIN) and a dynamic range (DR) stored in, and a quantization code corresponding to each pixel; A block reconfiguration step of identifying the position of a restored block based on the block repartition information stored in the block and executing the block reconfiguration.