JPH05284369A - Method and device for encoding/restoring image data - Google Patents

Abstract

PURPOSE:To enhance the efficiency by encoding only an effective block in which there is a variation in the same position of the previous image and the present image and omitting code data in the whole image, and also, to prevent deterioration of the picture quality by deciding it to be a scene change, when the effective block is above a threshold, and encoding the whole image. CONSTITUTION:Image data is written in a buffer 11, and thereafter, sent to a variation deciding part 13 by one block each, compared with a reference image of a reference frame holding part 12, its variation is compared with a threshold of a discriminating threshold holding part 14, and a result of deciding whether it is an effective block or not is inputted to an information holding part 16. Subsequently, only the effective block is encoded by an encoding part 19, and on the other hand, the number of effective blocks of one frame is counted by a counting part 15, and when it exceeds a threshold of a scene change discriminating threshold holding part 17, it is devided to be a scene change frame and all the blocks are changed to the effective blocks and encoded. In such a way, the block which is scarcely varied is not encoded and the efficiency is enhanced, and also, even at the time of scene change, deterioration of the image can be prevented.

Description

Detailed Description of the Invention

(Table of Contents) Industrial Application Field of the Prior Art (FIGS. 9 to 10) Problems to be Solved by the Invention Means for Solving the Problems (FIGS. 1 to 3) Working Example (a) First Example Description of Embodiments (FIGS. 4 to 6) (b) Description of Second Embodiments (FIGS. 7 to 8) (c) Description of Other Embodiments

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen data encoding / restoring method and apparatus for dividing image data into m × n blocks and encoding each block.

Image data has an enormous amount of data as compared with code data. In particular, in order to store halftone image data and color image data, or to transmit at high speed and high quality, the level of each pixel is high. It is necessary to encode the key value with high efficiency.

An example of such a highly efficient compression method for image data is an adaptive discrete cosine transform coding method.
Adaptive Discrete Coding
sine Transform) divides an image into blocks of 8 × 8 pixels, transforms the image signal of each block into a coefficient of spatial frequency distribution by two-dimensional discrete cosine transform (hereinafter referred to as DCT), and a threshold adapted to the visual sense. The quantized coefficient obtained by the above is encoded by the Huffman table obtained statistically.

In such a multi-valued image coding method, it is required to efficiently code continuous images.

[0006]

9 and 10 are explanatory views (No. 1) and (No. 2) of the prior art. In a conventional still image coding apparatus, each image is coded independently even if there is a large correlation between the images and a small change, such as an animation image considered as a set of still images.

For example, in the adaptive discrete cosine change coding system shown in FIG. 9, as shown in FIG. 9A, the block buffer 10 holds one block (8 × 8 pixels) of data,
The two-dimensional DCT transform unit 22 transforms the image signal of each block into a coefficient of the spatial frequency distribution by the two-dimensional discrete cosine transform, and the quantizing unit 23 quantizes it with a threshold adapted to the visual sense, and the quantized coefficient is variable-length coded. The variable length code is output by the Huffman table statistically obtained by the unit 24 and output.

Similarly, on the decompression side of FIG. 9B, the encoded data is decoded into a fixed length by the variable length decoding unit 36,
Inverse quantization is performed by the inverse quantization unit 37 to restore the DCT coefficient,
The inverse DCT conversion unit 38 converts the image into a block image, and the in-block pixel writing control unit 39 writes the restored image in the block address position of the block address generation unit 40 of the image memory 34.

Further, in the moving picture coding technique for a continuous scene such as a video conference apparatus, each picture is coded independently. That is, as shown in FIG. 10 (A), the difference between the block image of the image memory 28 holding the previous image and the block image of the current image is calculated by the difference image generation unit 29 and held by the block buffer 10. Two-dimensional DCT transform unit 22
Then, the image signal of each block is converted into a coefficient of the spatial frequency distribution by the two-dimensional discrete cosine transform, and is quantized by the quantizer 23 with a threshold adapted to the visual sense, and the quantized coefficient is statistically calculated by the variable-length encoder 24. A variable-length code is output according to the obtained Huffman table and output.

Further, the quantized coefficient is inversely quantized by an inverse quantizer 25 and inversely transformed into a DCT coefficient, and then inverse DCT transformed by an inverse DCT transformer 26 to be converted into a difference block image, which is then stored in an image memory. The previous image of 28 and the addition unit 27 add,
The image memory 28 is updated.

Similarly, on the decompression side of FIG. 10B, the encoded data is decoded into a fixed length by the variable length decoding unit 36, dequantized by the dequantization unit 37, and decompressed into DCT coefficients. , The inverse DCT conversion unit 38 converts the difference block image,
The in-block pixel writing control unit 39 writes the image obtained by adding the difference image and the previous image in the adding unit 41 to the block address position of the block address generating unit 40 of the image memory 34.

[0012]

However, in the conventional technique, the conventional still image coding technique has the following problems, but although the device can be configured with a small-scale circuit, an image with little change between images can be obtained. On the other hand, since each image is encoded independently, like an image of a videophone with a fixed animation or camera,
Even if there is very little change between consecutive images, the compression rate cannot be increased.

When a moving picture coding technique is used,
Due to the differential encoding, the compression rate is increased, but the device becomes large-scale. Therefore, the present invention efficiently encodes / restores a continuous image having a small change between images with a small-scale circuit, and an image data encoding / restoring method capable of preventing image deterioration at the time of a scene change. It is an object to provide the device.

[0014]

FIG. 1, FIG. 2 and FIG. 3 are principle diagrams (No. 1), (No. 2) and (No. 3) of the present invention.

According to claim 1 of the present invention, as shown in FIG.
In an image data coding method of coding image data in m × n pixels as blocks, a change amount of pixels at the same position in a block at the same position in a current image and a previous image is detected,
Determining whether or not the contents of the block have changed,
The step of counting the number of valid blocks determined to have changed in the one screen, the step of determining whether the number of valid blocks is a predetermined threshold value or more, and the block information which is the result of the determination Encoding a block of an image and outputting the block information as restoration information, and encoding all blocks of the current image as effective blocks when the number of effective blocks is equal to or more than a predetermined threshold value. The output block information is changed to the valid block.

According to the second aspect of the present invention, as shown in FIG.
In an image data coding method of coding image data in m × n pixels as blocks, a change amount of pixels at the same position in a block at the same position in a current image and a previous image is detected,
Determining whether or not the contents of the block have changed,
The step of counting the number of valid blocks determined to have changed in the one screen, the step of determining whether the number of valid blocks is a predetermined threshold value or more, and the block information which is the result of the determination Encoding a block of an image and outputting the block information as restoration information, and encoding all blocks of the current image as effective blocks when the number of effective blocks is equal to or more than a predetermined threshold value. The scene change information is output as the output restoration information.

A third aspect of the present invention is characterized in that, in the first or second aspect, the encoding step is an orthogonal transformation in the block unit. According to a fourth aspect of the present invention, in an image data encoding device that encodes image data using m × n pixels as blocks, a previous image holding means 12 for holding a previous image and a current image holding for holding a current image. Means 11, block change determining means 13 for detecting a change in pixel value in a block at the same position of the previous image and the current image and determining whether or not there is a change in the content of the block, and the determination result as block information. The block information holding means 16 for holding, the counting means 15 for counting the number of effective blocks which have been changed from the determination result, and the counting means 15 when it is determined whether or not all blocks of the current image have changed Comparing means 18 for comparing the contents of the above with a threshold value, and encoding means 1 for encoding an image in block units according to the block information.
9, and all of the block information of the block information holding means 16 is changed to a valid block when the number of valid blocks is equal to or more than a threshold value.

According to a fifth aspect of the present invention, image data is m × n.
In the image data encoding device that encodes each pixel as a block, the previous image holding unit 12 that holds the previous image
A current image holding means 11 for holding the current image, and a block change determination means for detecting a change in pixel value in a block at the same position of the previous image and the current image to determine whether or not there is a change in the contents of the block. 13, a block information holding unit 16 that holds the determination result as block information, a counting unit 15 that counts the number of valid blocks that have been changed from the determination result, and a change of all blocks of the current image. When the presence / absence is judged, it has a comparing means 18 for comparing the content of the counting means 15 with a threshold value, and an encoding means 19 for encoding an image in block units according to the block information. When it is equal to or more than the threshold value, scene change information is output and all the blocks of the current image are encoded.

A sixth aspect of the present invention is characterized in that, in the fourth or fifth aspect, the encoding means 19 performs an orthogonal transform in the block unit. According to a seventh aspect of the present invention, in the image data restoration method for restoring the encoded data according to the first aspect, a step of separating input data into encoded data and restoration information, and restoring an image block from the encoded data. It is characterized by including a step, a step of calculating a write address based on the restoration information, and a step of writing the restored image block in an image memory according to the calculated address.

According to claim 8 of the present invention, as shown in FIG.
An image data restoration method for restoring encoded data according to claim 2, wherein an image block is restored from the encoded data, a step of determining whether the restoration information is scene change information or block information, the scene change information or the scene change information It is characterized by including a step of calculating a write address based on the block information and a step of writing the restored image block in the image memory according to the calculated address.

According to a ninth aspect of the present invention, in the image data restoration device for restoring the encoded data encoded by the encoding device according to the fourth aspect, the restoration means 32 for restoring the image block from the encoded data, and the restoration. It is characterized by having a restoration control means 33 for calculating a write address based on information and an image memory 34 for storing the restored image block according to the calculated address.

According to a tenth aspect of the present invention, in an image data restoration device for restoring the encoded data encoded by the encoding device according to the fifth aspect, a restoration means 32 for restoring an image block from the encoded data, and restoration. Restoration information discriminating means 35 for discriminating whether the information is scene change information or block information.
And the restoration control means 33 for calculating the write address based on the determined scene change information or block information.
And an image memory 34 for storing the restored image block according to the calculated address.

[0023]

According to the first and fourth aspects of the present invention, among the blocks at the same position of the previous image and the current image, only the image block having a change from the previous image is selected and coded. For many images, the code data required for the entire image can be largely omitted.

Further, since the presence / absence of a change in each block is output as block information, even in this way, the block having a change can be identified on the restoration side. Further, when the number of effective blocks is equal to or more than the threshold value, it is determined that a scene change has occurred, and the entire current image is encoded instead of encoding only the effective blocks. Therefore, even in this case, deterioration of image quality can be prevented.

According to the second and fifth aspects of the present invention, among the blocks at the same position of the previous image and the current image, only the image block having a change from the previous image is selected and coded. For many images, the code data required for the entire image can be largely omitted.

Further, since the presence / absence of change in each block is output as the restoration information, the block having the change can be identified on the restoration side even in this way. Furthermore, when the number of effective blocks is equal to or more than the threshold value, a color image or the like is deteriorated in image quality as a color image. Therefore, it is determined as a scene change and the entire current image is encoded instead of encoding only the effective block. Therefore, even in this case, it is possible to prevent the deterioration of the image quality, and further, since the restoration information is sent as the scene change information, the restoration information amount can be reduced.

In claims 3 and 6 of the present invention, since the encoding is performed by orthogonal transformation, the circuit scale is reduced,
The compression rate can be increased. Claims 7 and 9 of the present invention
In this case, since the restored image is written at the address position obtained from the block information, even if only the effective block is encoded and output, only the changed block image can be updated, and at the time of the scene change, all images can be updated.

In the eighth and tenth aspects of the present invention, since the restoration information is discriminated as the scene change information or the block information and the writing control is performed, even if only the effective block is encoded and outputted, only the changed block image is outputted. Can be updated and all images can be updated when the scene changes.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (a) Description of the First Embodiment FIG. 4 is a block diagram of the encoding unit of the first embodiment of the present invention, FIG. 5 is a configuration diagram of the essential parts of the first embodiment of the present invention, and FIG. In FIG. 4, which is a configuration diagram of a restoration unit according to the first embodiment of the present invention, 11 is an image buffer, which holds input image data, 12 is a reference frame holding unit, which is a previous image for one screen. Is a block change determination unit, which compares the image block from the image buffer 11 and the block image at the same block position of the reference frame holding unit 12 on a pixel-by-pixel basis to calculate the amount of change in pixel value. The change amount of the pixel value in the block is compared with the determination threshold value of the determination threshold value holding unit 14 to determine the content change of each block.

Reference numeral 15 is an effective block counting unit, which increments by 1 and counts the number of effective blocks in one screen in response to the change (effective block) judgment of the block change judgment unit 12, and 16 holds block information. Determination information of the block change determination unit 13 (“1” when there is a change,
One that holds "0") for one screen without change, 17
Is a scene change determination threshold value holding unit that holds a threshold value for scene change determination (for example, a value of 70% of the total number of blocks).

Reference numeral 18 denotes a comparison unit, which determines whether or not there is a block change in one screen, and then compares the effective block counting unit 15 with the determination threshold of the scene change determination threshold value holding unit 17 to determine a scene change. , Block information holding unit 1
Rewriting the block information of 6 into a valid block, 1
An encoding unit 9 encodes each block of the image buffer 11 according to the block information of the block information holding unit 16 as shown in FIG.

The structure of the encoding unit 19 will be described with reference to FIG. 5A. Reference numeral 22 is a DCT transform unit, which performs a two-dimensional discrete cosine transform on the transmitted block image to obtain a spatial frequency distribution coefficient. What is transformed, 23 is a quantizer,
Quantization coefficient is obtained by quantizing the coefficient of the spatial frequency distribution with a threshold adapted to the visual sense of the quantization threshold holding unit 23a,
Reference numeral 24 denotes a variable length coding unit, which is a Huffman code table holding unit 2
4a, the quantized coefficient is variable length coded by the Huffman table.

The encoding operation of the configurations of FIGS. 4 and 5 will be described. The input image data is written in the image buffer 11, and the image buffer 11 sends the original image to the block change determination unit 13 block by block.

The block change determination unit 13 compares the pixel of the block with the pixel at the same position of the block of the reference image held in the reference frame holding unit 12,
The amount of change is accumulated for one block, and the determination threshold holding unit 1
4 is compared with the threshold value of 4 to determine whether or not the block is a valid block, and the determination result is the block information holding unit 16
Output to.

The block information holding unit 16 holds "1" for a valid block and "0" for an invalid block as block information for all blocks on one screen. on the other hand,
If the determination result is a valid block, the valid block counting unit 15 increments the counter by 1 and counts the number of valid blocks in one frame (one screen).

When the determination is completed for all of the one frame, the comparison unit 18 compares the counting result of the valid block counting unit 15 with the threshold value of the scene change determination threshold value holding unit 17, and the counting result is equal to or more than the threshold value. In this case, the block information holding unit 16 determines that it is a scene change frame.
All blocks (for example, 720 × 57 in the PAL system).
Since there are 6 pixels, an 8 × 8 block has 90 × 72 = 64
Block information of 80) is a valid block (“1”)
Change to.

Of course, if the counting result is less than the threshold value, the block information in the block information holding unit 16 is not changed.
The block information of the block information holding unit 16 is the same as the encoding unit 1.
9, and the encoding unit 19 encodes only the effective block of the image buffer 11.

Then, a multiplexer (not shown) outputs the encoded data of the effective block of the encoding unit 19 after the block information of the block information holding unit 16 of 6480 bits.

The reference frame rewriting signal for the effective block is generated by the block information of the block information holding unit 16, and the reference frame holding unit 12 updates the effective block.

As described above, since the effective block having a change is determined with respect to the previous image and only the effective block is encoded, the encoding amount can be greatly reduced, and even if only the effective block is output in this way. Since the block information is output, the block position of the effective block can be recognized on the restoration side, and the image can be restored.

Further, at the time of a scene change, all blocks are set as effective blocks, so that all blocks are coded and transmitted, so that it is possible to prevent image deterioration. In this case, when the image is composed of a plurality of components like a color image and is processed on a component-by-component basis, one component at the time of scene change has little change before and after the scene change. When the component is not considered to be a scene change, and when it is viewed as a color image even if the image quality of each component is not deteriorated, 1
The color difference becomes more severe than the component error, and the deterioration of the image quality becomes remarkable.

Therefore, when one component is regarded as a scene change, all the components are changed to a scene change, so that the deterioration of image quality can be prevented. Next, regarding the restoration side,
This will be described with reference to FIGS.

FIG. 6 is a block diagram of the restoration unit according to the first embodiment of the present invention. In FIG. 6, 30 is a demultiplexer, which separates input data into block information and encoded data, 31 is a block information holding unit, which holds sent block information, and 32 is restoration Part, which decodes encoded data and restores a restored image,
This will be described with reference to FIG.

A restoration control unit 33 detects the number of consecutive invalid blocks from the block information, skips the address of the invalid block, and sends the block address of the valid block to the image memory 34, and 34 is an image memory. This is a one-screen memory, and one block image of the decoding unit 32 is written at the position of the effective block address of the restoration control unit 33.

The decoding unit 32 will be described with reference to FIG. 5B. Reference numeral 36 is a variable length decoding unit, and variable length coding is performed with a fixed length by the Huffman table statistically obtained by the Huffman decoding table holding unit 36a. To convert to quantized coefficients of
Is an inverse quantization unit, which linearly inversely quantizes (multiplies) the quantized coefficient with the threshold of the inverse quantization threshold holding unit 37a to convert into a coefficient of spatial frequency distribution, and 38 is an inverse DCT conversion unit , The spatial frequency distribution coefficient is subjected to inverse two-dimensional discrete cosine transform to restore it to an image block (image space data).

5 and 6, the demultiplexer 30 separates the input data into code data and block information, the code data is sent to the decoding section 32, and the block information is Block information holding unit 3
Held at 1.

The variable-length code data of the code data is restored to the fixed-length quantized coefficient from the decoding table 36a having a configuration opposite to that of the code table used on the encoding side in the variable-length decoding unit 36, and the obtained inverse quantization is obtained. The coefficient is linearly inversely quantized by the inverse quantization unit 37 using the inverse quantization threshold 37a and output to the inverse DCT transform unit 38. The inverse DCT transform unit 38 transforms the inverse quantized coefficient into a two-dimensional inverse DCT transform. Then, it is converted into image space data (restored image).

These processes are performed in block units. On the other hand, with respect to the block information, the restoration control unit 33 counts the existence of valid blocks and the number of invalid blocks, calculates an address for writing the restored image of the decoding unit 32 in the frame memory 34, and sends the address to the frame memory 34. , Write the restored image according to the address information.

In this way, even when the code data of the effective block is sent, the block address of the effective block can be calculated from the block information, and the block image at the corresponding position on the screen can be updated.

(B) Description of the Second Embodiment FIG. 7 is a block diagram of the encoding unit of the second embodiment of the present invention, and FIG. 8 is a block diagram of the reconstruction unit of the second embodiment of the present invention.

In FIG. 7, the same components as those shown in FIGS. 4 and 5 are designated by the same symbols, and 20 is a scene change information holding unit, which holds, for example, 8-bit scene change information. Reference numeral 21 denotes a multiplexer, which selectively outputs the scene change information or the block information of the block information holding unit 16 by the output of the comparison unit 18.

To describe the encoding operation of this configuration, the input image data is written in the image buffer 11,
The image buffer 11 sends the original image to the block change determination unit 13 block by block.

The block change determination unit 13 compares the pixel of the block with the pixel at the same position of the block of the reference image held in the reference frame holding unit 12,
The amount of change is accumulated for one block, and the determination threshold holding unit 1
4 is compared with the threshold value of 4 to determine whether or not the block is a valid block, and the determination result is the block information holding unit 16
Output to.

The block information holding unit 16 holds "1" for a valid block and "0" for an invalid block as block information for all blocks on one screen. on the other hand,
If the determination result is a valid block, the valid block counting unit 15 increments the counter by 1 and counts the number of valid blocks in one frame (one screen).

When the determination is completed for all of the one frame, the comparison unit 18 compares the counting result of the valid block counting unit 15 with the threshold value of the scene change determination threshold value holding unit 17, and the counting result is equal to or more than the threshold value. If it is a scene change frame, the multiplexer 21 is switched to the scene change information holding unit 20 and the scene change information is output as restoration information. If the count result is less than the threshold value, the block information holding unit 16 is output. The block information is switched and the block information of the block information holding unit 16 is output as the restoration information.

With this restoration information, the coding unit 19 performs coding, scene change information is coded for all blocks in the image buffer 11, and is output, and block information is image buffer 11 Only the effective blocks of are encoded.

Then, by the multiplexer (not shown), after the restoration information of the multiplexer 21, the encoding unit 1
The encoded data of 9 effective blocks is output. It should be noted that the reference frame rewriting signal is generated for the effective block according to the restoration information of the multiplexer 21, and the reference frame holding unit 12 updates the effective block.

As described above, since the effective block having a change is determined with respect to the previous image and only the effective block is encoded, the encoding amount can be greatly reduced, and even if only the effective block is output in this way. Since the restoration information is output, the block position of the effective block can be recognized on the restoration side, and the image can be restored.

Further, at the time of a scene change, all blocks are treated as effective blocks, so that all blocks are coded and transmitted, and it is possible to prevent image deterioration. Further, when a scene is changed, 8-bit scene change information is output as restoration information, so that the restoration information can be reduced from 6480 bits to 8 bits.

Next, the restoration unit will be described with reference to FIG. In FIG. 8, the same components as those shown in FIG. 6 are designated by the same symbols, and 35 is a restoration information discriminating section, which discriminates scene change information and block information from the restoration information,
The scene change information is sent to the restoration control unit 33, and the block information is sent to the block information holding unit 31.

Next, the restoration operation of FIG. 8 will be described. The input data is separated by the demultiplexer 30 into code data and restoration information, the code data is sent to the decoding section 32, and the restoration information is judged as restoration information. The scene change information is sent to the unit 35, it is discriminated whether it is scene change information or block information, the scene change information is output to the restoration control unit 33, and the block information is held in the block information holding unit 31.

The variable-length code data of the code data is restored to a fixed-length quantized coefficient from the decoding table 36a having a configuration opposite to that of the code table used on the encoding side by the variable-length decoding unit 36, and the obtained inverse quantum is obtained. The dequantization coefficient is linearly dequantized by the dequantization unit 37 using the dequantization threshold value 37a and output to the inverse DCT conversion unit 38. The inverse DCT conversion unit 38 outputs the dequantized coefficient to the two-dimensional inverse DCT. It is converted and converted into image space data (restored image).

These processes are performed in block units. On the other hand, with respect to the block information, the restoration control unit 33 counts the existence of valid blocks and the number of invalid blocks, calculates an address for writing the restored image of the decoding unit 32 in the frame memory 34, and sends the address to the frame memory 34. , Write the restored image according to the address information.

Further, according to the scene change information, the restoration control section 33 sequentially generates the addresses of all blocks and sends them to the frame memory 34. In the frame memory 34, according to the address information, the restored image of all blocks from the decoding section 32. Write.

In this way, even if the code data of the effective block is sent, the block address of the effective block can be calculated from the restoration information, and the block image at the corresponding position on the screen can be updated.

(C) Description of Other Embodiments In addition to the above embodiments, the present invention can be modified as follows. In the above-described embodiment, the address counter is idly fed depending on the number of valid blocks, but the number of invalid blocks may be added to the value of the address counter.

The coding unit and the restoration unit are shown as blocks.
You can run it. When the block information in the block information holding unit is binary-coded, the amount of information can be further reduced. Only the coded data of the valid block is transmitted without transmitting the block information for the valid block, and the number of invalid blocks following it is calculated. The amount of information can be reduced even when transmitted following the coded data of the effective block.

The present invention has been described above with reference to the embodiments.
Various modifications are possible within the scope of the invention, and these modifications are not excluded from the scope of the invention.

[0069]

As described above, according to the present invention,
It has the following effects. Only blocks that have been determined to have changed between the previous image and the current image are selected and encoded and output, so the compression rate when there is little change between images can be greatly improved, and the videophone with a fixed camera It is possible to increase the average compression rate of images such as images and animation images.

Even in this case, since the restoration information is output, the position of the effective block can be recognized and the changed screen can be obtained. The number of effective blocks in one frame is counted, and if the count value is equal to or larger than a specified value, it is determined that a scene change has occurred, and all blocks are coded and output, so that image deterioration can be prevented.

[Brief description of drawings]

FIG. 1 is a principle diagram (1) of the present invention.

FIG. 2 is a principle diagram (2) of the present invention.

FIG. 3 is a principle diagram (3) of the present invention.

FIG. 4 is a configuration diagram of an encoding unit according to the first embodiment of this invention.

FIG. 5 is a configuration diagram of a main part of a first embodiment of the present invention.

FIG. 6 is a configuration diagram of a restoration unit according to the first embodiment of this invention.

FIG. 7 is a block diagram of an encoding unit according to a second embodiment of the present invention.

FIG. 8 is a configuration diagram of a restoring unit according to a second embodiment of the present invention.

FIG. 9 is an explanatory diagram (1) of a conventional technique.

FIG. 10 is an explanatory view (No. 2) of the conventional technique.

[Explanation of symbols]

 11 Image Buffer 12 Reference Frame Holding Unit 13 Block Change Determination Unit 15 Effective Block Counting Unit 16, 31 Block Information Holding Unit 19 Encoding Unit 20 Scene Change Information Holding Unit 21 Multiplexer 30 Demultiplexer 32 Decoding Unit 33 Restoration Control Unit 34 Image Memory 35 Restoration Information Discrimination Section

Claims (10)

[Claims] 1. Image data is blocked in m × n pixels.
In the image data encoding method, the pixel at the same position in the block at the same position as the current image and the previous image
The amount of change in the block is detected to determine whether the contents of the block have changed.
Setting step and there is a change according to the judgment in one screen
Counting the number of valid blocks generated,
Step to determine whether the number of locks is greater than or equal to a predetermined threshold
According to the block information which is the determination result,
Encoding the block and recovering the block information
Outputting as original information, and when the number of effective blocks is equal to or more than a predetermined threshold value, the current image
All blocks of the
Change the block information that applies to the valid block
An image data encoding method characterized by: 2. An image data encoding method for encoding image data in which m × n pixels are used as a block, and a change amount of a pixel at the same position of a block at the same position of a current image and a previous image is detected, A step of determining whether or not there is a change in the contents of the block, a step of counting the number of effective blocks which have been changed by the determination in one screen, and a step of determining whether or not the effective block number is a predetermined threshold value or more And a step of encoding a block of the current image according to the block information which is the determination result, and a step of outputting the block information as restoration information, when the effective block number is equal to or more than a predetermined threshold value. An image data encoding method characterized in that all blocks of the current image are encoded as effective blocks and scene change information is output as the restoration information to be output. . 3. The encoding step is an orthogonal transformation in the block unit.
Or the image data encoding method of 2. 4. An image data encoding method for encoding image data by using m × n pixels as blocks, and a previous image holding means (12) for holding a previous image and a current image holding means for holding a current image. (11), a block change determination means (13) for determining the presence or absence of a change in the content of the block by detecting a change in the pixel value in the block at the same position of the previous image and the current image, and the determination result. Block information holding means (16) for holding as block information, counting means (15) for counting the number of effective blocks that have been changed from the determination result, and determination of whether or not all blocks of the current image have changed When this is done, it has a comparing means (18) for comparing the content of the counting means (15) with a threshold value, and an encoding means (19) for encoding an image in block units according to the block information, Number of blocks The pixel data encoding device is characterized in that all of the block information of the block information holding means (16) are changed to valid blocks when is greater than or equal to a threshold value. 5. An image data encoding device for encoding image data by using m × n pixels as blocks, and a previous image holding means (12) for holding a previous image and a current image holding means for holding a current image. (11), a block change determination means (13) for determining the presence or absence of a change in the content of the block by detecting a change in the pixel value in the block at the same position of the previous image and the current image, and the determination result. Block information holding means (16) for holding as block information, counting means (15) for counting the number of effective blocks that have been changed from the determination result, and determination of whether or not all blocks of the current image have changed When this is done, it has a comparing means (18) for comparing the content of the counting means (15) with a threshold value, and an encoding means (19) for encoding an image in block units according to the block information, Number of blocks Is greater than or equal to a threshold value, scene change information is output to encode all blocks of the current image. 6. The image data coding apparatus according to claim 4, wherein the coding means (19) performs an orthogonal transform on the block unit basis. 7. The image data restoration method according to claim 1, wherein the input data is separated into encoded data and restoration information, and an image block is restored from the encoded data. An image data restoration method comprising: a step of calculating a write address based on the restoration information; and a step of writing the restored image block in an image memory according to the calculated address. 8. The image data restoration method according to claim 2, wherein the image data is restored from the encoded data.
The method includes a step of determining whether the restoration information is scene change information or block information, a step of calculating a write address based on the scene change information or the block information, and a step of writing the restored image block in the image memory according to the calculated address. An image data restoration method characterized by the above. 9. An image data restoring device for restoring the encoded data encoded by the encoding device according to claim 4, wherein the restoring means (3) restores an image block from the encoded data.
An image data restoration device comprising: 2), restoration control means (33) for calculating a write address based on restoration information, and an image memory (34) for storing the restored image block according to the calculated address. 10. An image data restoring device for restoring the encoded data encoded by the encoding device according to claim 5, wherein the restoring means (3) restores an image block from the encoded data.
2), restoration information discriminating means (35) for discriminating whether the restoration information is scene change information or block information, and restoration control means (33) for calculating a write address based on the discriminated scene change information or block information. And an image memory (34) for storing the restored image block according to the calculated address.