JP2798025B2 - Video coding method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for encoding moving picture data.

[0002]

2. Description of the Related Art At present, the contents of characters such as books, newspapers, magazines, comic books, animations, etc., line drawings, photographs, moving images, etc. are converted into electronic data and optical data as character data and binary or multi-valued image data. Alternatively, devices have been developed that record the data on a magnetic recording medium, read the recorded data from the recording medium, convert the data into a display image, and display the image on various display devices. As a display device,
For example, a CRT device, a plasma display device, a liquid crystal display device often used for a portable terminal, and the like can be given. The purpose of developing these devices is to record and supply information that has been fixed and distributed by printing on paper to a recording medium, to protect paper resources, and to create a paper book. To provide information with a high density by adding a function that does not exist.

[0003] In addition, due to the recent trend toward multimedia, data that cannot be expressed in the form of printing on paper, such as moving images and sounds, has been included in data. These data include binary or multi-valued image data, such as animation, which is called a simple moving image and is composed of a plurality of frames.

[0004] Binary or multi-valued image data may be subjected to dither processing in order to be displayed on a liquid crystal display device capable of displaying eight or sixteen colors. The dithered image data (dither image data) is binary data when observed one pixel at a time. However, when an image is observed at a certain distance or more, the luminance is high in an area where white pixels are relatively large. In a region where black pixels occupy a relatively large amount, the luminance appears to be low, and as a result, the density of an image can be displayed.

As the dither processing, an organized dither method and an error diffusion dither method are widely used. In the systematic dither method, the target image is regarded as a set of sub-matrices of n × n dots, a threshold is determined only by coordinate information in the sub-matrix, and the threshold is compared with the threshold. This is converted into a binary signal which is 1 "(white) and" 0 "(black) if small. The error diffusion dither method changes the threshold processing according to the density of pixels around the pixel to be binarized, and adds the error obtained by comparison to the value of the next pixel. is there.

On the other hand, when recording is performed on a recording medium having a small recording capacity such as a floppy disk, or when there is a huge amount of image data having a large data amount, it is necessary to perform data compression. As a compression method of binary or multi-valued image data, only the correlation of image signals in the same line is used.
Modified Huffman coding (hereinafter referred to as MH coding or MH), which is a two-dimensional coding method, and Modified Read, which is a two-dimensional coding method that also uses the correlation between adjacent lines. ) Coding (hereinafter referred to as MR coding or MR) is known, and MH coding and MR coding are widely used in facsimile and the like.

When a dither image is coded using MH coding or MR coding, the code amount is larger than the total number of bits of the original image signal. Often becomes large. This is because the image data obtained by the dither processing has no periodicity and has almost no correlation with neighboring pixels, and is not suitable for data compression. Therefore, various encoding methods for efficiently compressing a halftone image by the dither method have been studied.

Japanese Patent Application Laid-Open No. 64-77371 discloses a method of encoding a halftone image using a dither method, which can improve the encoding efficiency without deteriorating the image quality of the halftone image. Discloses a method of encoding only a difference component between a previously processed binary signal and a currently processed binary signal. FIG.
FIG. 1 is a block diagram illustrating a configuration of an encoding device disclosed in Japanese Patent No. The encoding apparatus includes a halftone image buffer 401 that stores a halftone image before being subjected to dither processing,
For example, a dither processing circuit 40 having a Bayer type dither matrix as shown in FIG. 12 and performing dither processing on image data in the halftone image buffer 401.
2, a comparison processing circuit 403 for comparing the previous and current binary signals subjected to the systematic dither processing, and a comparison processing circuit 40
A comparison data storage buffer 404 for temporarily storing a binary signal for performing the comparison in 3, an encoding circuit 405 for encoding the comparison result in the comparison processing circuit 403, and storing the encoded data. A code memory 406 is used.

Next, the operation of the encoding apparatus will be described step by step with reference to FIGS. The halftone image buffer 401 stores a halftone image of M rows × N columns and M · N gradations, and here, 16 rows of 4 rows × 4 columns.
It is assumed that it is gradation. When the halftone images are sequentially read from the halftone buffer 401, the dither processing circuit 402 performs a binarization process by the systematic dither method with these halftone images as input, and sends the dither image to the comparison processing circuit 403. . Here, attention is paid to the encoding of the n-th halftone image in the halftone image buffer 401.

FIGS. 13A, 13B, and 13C show n-1, n, and n + 1.
The binary patterns obtained secondly and sent to the comparison processing circuit 403 are shown. Assuming that the (n-1) -th binary pattern processed last time is stored in the comparison data storage buffer 404,
, The (n−1) -th binary pattern is read out, and compared with the n-th binary pattern currently being processed in the comparison processing circuit 403, and a difference pattern between these binary patterns is obtained. Here, a difference pattern as shown in FIG. 14 (a) is obtained, and since all the elements of the difference pattern are 0, n
It is determined that the -1st and n-th binary patterns are the same, and that fact is transmitted to the encoding circuit 405. Further, the comparison processing circuit 403 stores the n-th binary pattern in the comparison data storage buffer 404 so as to be used as a comparison sample for the next (n + 1) -th binary pattern.

Next, assuming that a binary pattern of the (n + 1) th halftone image is obtained as shown in FIG.
In the same manner as in the case of the n-th binary pattern, the comparison processing circuit 403 compares the (n + 1) -th binary pattern with the n-th binary pattern.
A pattern as shown in (b) is obtained. In this difference pattern, an element of “1” indicates a mismatched portion. Here, if the address of the mismatched portion is represented using the matrix shown in FIG.
There will be a mismatch at the first and fifteenth addresses.

Since the n-th binary pattern and the (n-1) -th binary pattern are the same, the encoding circuit 405 counts the coincidence code "E" corresponding to the n-th binary pattern. A code with the number "+1" is generated. If the same binary pattern continues, the count number is accumulated. This code is encoded by the encoding circuit 4
05 is stored in the code memory 406. In addition, since the n-th binary pattern and the (n + 1) -th binary pattern do not match as described above, in this case, the encoding circuit 405 determines whether the mismatching occurs as shown in FIG. A code having the code “B” and unmatched portion information is generated and stored in the code memory 406. The mismatch location information is 16 bits long, and the bit at the position corresponding to the mismatch, here,
By setting the fifth, seventh, eleventh, and fifteenth bits to “1”, a mismatched portion is represented.

An example of a continuous image coding apparatus for compressing a plurality of pieces of continuous image information having a high correlation between adjacent frames of a continuous image is described in JP-A-1-303988. This continuous image encoding device encodes only the place where data changes between frames, that is, only the moving part, by performing run-length encoding in the time axis direction on pixels of image data spanning a plurality of frames, It is intended to reduce the amount of data in a scene with little movement and to further smooth the movement of animation such as graphics. FIG.
1 shows a continuous image encoding device described in Japanese Patent No. 3988. That is, the continuous image encoding device includes an image data input unit 501 that captures image information (continuous image data) continuous to a plurality of frames, and an image data input unit 501.
A continuous image compression unit 502 that performs run-length compression of each pixel in the time series direction from the continuous image data input to the storage unit, and a storage medium such as an optical disk that stores pixel information for each frame encoded by the continuous image compression unit 502 503
A continuous image expansion unit 504 that reads out pixel information for each frame from the storage medium 503 and performs run-length expansion in a time-series direction, and a display memory 505 in which display data expanded by the continuous image expansion unit 504 is written. And a display 506 for displaying the display data written in the display memory 505.

Next, the operation of the continuous picture coding apparatus will be described. Image data of all frames to be animated is input to the image data input unit 501, digitized for each frame, and output to the continuous image compression unit 502 in ascending frame number order. The continuous image compression unit 502 sequentially compares the input digital data on a frame-by-frame basis, and outputs the color data of the pixel in which the color data has changed and the number of frames in which the color data has continued. Run length compression in the sequence direction is performed, and the color data and the number of frames (display time data) are recorded in the storage medium 503 in frame units. On the other hand, the continuous image decompression unit 504 reads out the compressed data from the storage medium 503 in frame units, decompresses the run-length code in the time series direction, and writes it in the display memory 505. The display memory 505 is a bitmap memory in which addresses correspond to display pixels on the display 506 on a one-to-one basis. Display data written to each address of the display memory 505 is directly converted and displayed on the display 506. You.

FIG. 17 shows the configuration of the continuous image compression unit 502. The continuous image compression unit 502 includes a first frame memory 521 and a second frame memory 522 for respectively storing the input pixel data of one frame, and a pixel at the same position in the frames respectively stored in the frame memories 521 and 522. A frame comparison circuit 523 for comparing data and outputting the information, a color data memory 524 for storing color data of each pixel of the currently used frame, and a color data memory 524 for each pixel currently stored in the color data memory 524. The display time data memory 525 indicating how many consecutive frames of the color data have the same value (same color) up to the current frame, and the number of pixels having different colors are counted as a result of comparison by the frame comparison circuit 523. Changed pixel counter 526 and pixels that have changed between pixels at the same position in one comparison between frames The data output FIFO memory 527 for storing the color data and the corresponding display time data until the comparison of the two frames is completed, and the change pixel number counter 526 each time the comparison between one frame is completed And an output control circuit 528 for controlling the output of the data output FIFO memory 527; an initial screen memory 529 for storing the data of the first screen (initial screen); An initial value discriminating circuit 530 for discriminating whether the data is screen data, and a switch for switching between inputting data to the initial screen memory 529 or inputting data to the data output FIFO memory 527 according to the discrimination result of the initial value discriminating circuit 530 531.

The relationship among the first frame memory 521 and the second frame memory 522, the color data memory 524, and the display time data memory 525 will be described with reference to FIG. I do. Each of the frame memories 521 and 522, the color data memory 524, and the display time data memory 525 are memories having an address space of the same size, and are arranged so as to have a relatively same positional relationship as shown in the drawing. Have been. Here, pixel information of two frames to be compared is written into the first frame memory 521 and the second frame memory 522, respectively, and pixels at the same display position are compared.
The result of comparing the pixels at the same display position is written in the color data memory 524 and the display time data memory 525 at addresses where the relative positional relationship is the same. As a result, the information of each pixel is stored in each of the memories 521, 522,
At 524 and 525, they are stored so as to have the same relative positional relationship.

Here, the procedure of the time-series direction run-length encoding performed by the continuous image compression unit 522 will be described with reference to the flowchart of FIG.

First, the continuous image compression unit 522 is initialized (step 601). Specifically, as shown in FIG. 20A, the changing pixel number counter 526 is set to “0” (step 621), and the data output FIFO memory 52 is set.
7 and reset the display time data memory 525 to "1".
(Step 622), the data of the first frame is written to the first frame memory 521 (step 623), and the contents of the first frame memory 521 are copied to the color data memory 524 (step 624). When the initialization processing in step 601 is completed, the data of the next frame is subsequently written into the second frame memory 522 (step 602), and the corresponding positions of the first frame memory 521 and the second frame memory 522 are written. Are compared (step 603), and it is determined whether the colors of the compared pixels are the same (step 604). If the color data is the same for the compared pixels, 1 is added to the contents of the corresponding display time data memory 225, and the routine proceeds to step 611.

On the other hand, if the colors of the pixels are different in step 604, whether the image data is the initial screen data by the initial value discriminating circuit 530, that is, the corresponding color data memory 5
It is determined whether the contents of the 24 color data are to be output for the first time (step 606). If the data is not the initial screen data, the data is output to the data output FIFO memory 527, and the color data of the corresponding pixel in the second frame memory 522 is written to the color data memory 524 as new data (step 607). And
The contents of the corresponding display time data memory 525 are also output to the data output FIFO memory 527, and "1" is written to the display time data memory 525 as new data (step 608). Subsequently, 1 is added to the content of the change pixel number counter (step 609), and the process proceeds to step 611. On the other hand, if it is determined in step 606 that the data is the initial screen data, an initial screen process is executed (step 610), and the process proceeds to step 611. In the initial screen processing, the contents of the color data memory 524 corresponding to the pixel position compared at this time are written into the corresponding position of the initial screen memory 529 by switching the switch 531, and the color of the corresponding pixel in the second frame memory 522 is written. The data is written as new data in the first frame memory 521, and the contents of the corresponding display time memory 525 are also written in the corresponding positions of the initial screen memory 529,
Display time data memory 52 with "1" as new data
5 is performed.

In step 611, it is determined whether all the pixel data for one frame have been compared. If there is a pixel that has not been compared, the process proceeds to step 602 to compare the pixel in the same manner as described above. If all the pixel data have been compared, the output process by the output control circuit 528 is performed. Execute (step 612). This output processing is performed as shown in FIG.
6 is output (step 631), then the content written in the data output FIFO memory 527 is output as it is (step 632), and finally, the end (end)
This is the process of outputting a code (step 633). When the output processing is completed, it is determined whether or not the frame data written in the second frame memory 522 is the last data (step 613).
If the frame data written in the second frame memory 22 is not the last data, the entire contents of the second frame memory 522 are copied to the first frame memory 521 (step 61).
4) Go to step 602 to write the next frame data to the second frame memory 522. on the other hand,
In step 613, the second frame memory 522
When it is determined that the frame data written in is the last data, it means that all the frame data have been compared, and the output processing is performed by the output control circuit 528 (step 615), and the processing ends. . Step 61
The output processing in step 5 is the same as the output processing in step 613. By performing the above operations,
The initial screen data of the animation and the subsequent rewritten screen data can be obtained in frame units.

In this continuous image coding apparatus, the time-series run-length coded data of a continuous image obtained by the continuous image compression unit 502 includes initial screen data as shown in FIG. ) And rewrite screen data as shown in FIG. FIGS. 21A and 21B show these initial screen data and rewritten screen data as data structures when stored in the storage medium 503. FIG.

At the head of the initial screen data, an initial screen code indicating that the time-series run-length encoded data starts from here is added, and at the end, an end code indicating the end of the frame is added. Change number data indicating how many pixels are rewritten in the frame is added to the head of the rewrite screen data of each frame, and an end code is added to the last part. Then, between the initial screen code and the end code (in the case of the initial screen data) and between the change number data and the end code (in the case of the rewritten screen data), the color data and the display time data alternately as shown in the figure. Deploy. Note that the initial screen code,
The change number code and the end mark are provided for convenience in data handling, and are not essential.

[0023]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Laid-Open Publication No.
In the method described in Japanese Patent No. 77371, the binary signal after the binarization processing using the systematic dither method is compared with the previously processed binary signal, and only the difference is encoded. Only when the current and the current binary signals match continuously, the compression ratio increases. On the other hand, if the two do not coincide with each other, the amount of data increases by the amount of the added matching code and non-matching code, and the compression rate is rather reduced. The dithered binary signal is 2 ¹⁶ = 65 in a 4 × 4 matrix.
Since there are 356 possible patterns, it is considered that there is a low possibility that the previous and current binary signals are continuously coincident. In the end, according to the method disclosed in Japanese Patent Application Laid-Open No. Sho 64-77371,
It is difficult to improve the compression ratio.

The method described in JP-A-1-303988 focuses on the fact that there is a high correlation between pixel information between adjacent frames in a continuous image composed of a plurality of frames, and performs run-length encoding in the time axis direction. Therefore, there is a problem that dither processing cannot be performed.

An object of the present invention is to solve the above-mentioned problems of the prior art, to improve the encoding efficiency of dither-processed image data, and to reduce image data composed of a plurality of frames, that is, moving image data, with a small code amount. An object of the present invention is to provide an encoding method and apparatus capable of encoding.

[0026]

According to the present invention, there is provided a moving picture coding method for coding moving picture data composed of a plurality of frames, wherein the dither processing is performed on the moving picture data. A processing step, a filling processing step of painting a part of the region of the moving image data subjected to the dither processing with the same color, and a compression processing step of performing compression encoding on the moving image data that has passed through the filling processing step And

In the moving picture coding method according to the present invention, a difference processing step for obtaining difference data between the moving picture data of the current frame and the moving picture data of the previous frame is provided after the painting processing step, and the difference processing step is performed based on the difference data. Compression encoding may be performed.

A moving picture coding apparatus according to the present invention is a moving picture coding apparatus for coding moving picture data composed of a plurality of frames, wherein a dither processing means for dithering the moving picture data; And a compression processing unit for performing a compression encoding based on the data output from the painting processing unit.

In the moving picture coding apparatus of the present invention, there may be provided a thinning-out processing means for thinning out the moving picture data inputted to the dither processing means, and the moving picture data of the current frame and the moving picture data of the previous frame may be provided. Difference processing means for obtaining difference data from the data may be provided on the output side of the painting means, and the difference data may be input to the compression processing means and encoded. As the difference processing means, means for obtaining exclusive OR of pixels at the same display position in the current frame and the previous frame to obtain difference data can be used. Further, as the difference processing means, a difference value obtaining means for obtaining a difference value for each pixel between the data of the current frame and the data of the immediately preceding frame, and comparing the difference value with a predetermined threshold value A difference value comparing unit that determines difference data, and when the difference value is equal to or smaller than the threshold value, a pixel that has no difference between the current frame and the immediately preceding frame for the pixel is also used. be able to.

That is, in the present invention, a partial area of the image data after the dither processing, typically, a non-moving area or a background area is painted in the same color.
The area of the dither region is reduced to reduce the amount of data after encoding. In particular, after performing the filling process, by calculating the difference between the current frame and the previous frame and performing compression encoding with this difference data, random data is converted to long white or black run data,
It is possible to further reduce the data amount after encoding. In this case, if the difference data is determined based on the comparison result by comparing the difference value with the threshold value, the difference can be obtained even for data having a small correlation between frames, and the run length is long. Data is obtained. Furthermore, by reducing the input data by performing frame thinning before performing dither processing, it is also possible to reduce the amount of data after encoding.

[0031]

Next, an embodiment of the present invention will be described with reference to the drawings.

<< First Embodiment >> FIG. 1 is a block diagram showing a configuration of a moving picture coding apparatus according to a first embodiment of the present invention. The moving picture coding apparatus includes a dither processing unit 11 for performing dither processing on input image data for each frame, and a same color for a non-moving area and a background area in the dither-processed image data. A filling means 12 for performing a filling process, and a difference processing means 13 provided on the output side of the filling means 12 for obtaining a difference between the previous frame data and the current frame data to obtain difference data
A compression processing unit 14 that performs compression processing on data output by the difference processing unit 13 and outputs encoded data;
It is composed of

The dither processing means 11 receives the binary or multi-valued image data composed of a plurality of frames and uses an error diffusion dithering method, an organized dithering method or a random number generating dithering method, etc. The dither processing is performed on the area, and the dither-processed data is supplied to the filling means 12. As shown in FIG. 2, the difference processing unit 13 includes a previous frame data storage unit 21 that stores data of the previous frame, and an inter-frame difference that calculates an exclusive OR for each pixel between the data of the current frame and the data of the previous frame. And a processing means 22. As a data compression and encoding method in the compression processing means 14, since the data to be compressed is data having binary or multi-valued gradation, the MH used in facsimile or the like is used.
Various lossless encoding methods such as encoding, MR encoding, MMR (Modified MR) encoding, slide dictionary type LZ (Lempel-Ziv) encoding that can perform high-speed decompression, and run-length encoding can be used.

Next, the operation of the moving picture coding apparatus will be described. FIG. 3 is a flowchart showing processing in the moving picture coding apparatus, and FIGS. 4A and 4B are diagrams showing examples of image data in two frames adjacent in time series. In FIG. 4, an outline area A means an area having a motion, and is shifted to the upper right from the nth frame to the (n + 1) th frame. On the other hand, a hatched area B in the figure indicates a static area or a background area. The dotted line indicates the position of the area A in the immediately preceding frame. Here, FIG. 4 (a),
It is assumed that image data as shown in (b) is input to the dither processing means 11.

First, dither processing is performed on the entire area of the image data (step 101). This process is performed on a frame basis until there is no more frame data to be input (step 102). Subsequently, the data subjected to the dither processing is input to the filling processing means 12, and the filling processing is performed for each frame (step 103). In the painting process, as described above, a non-moving area, a background area, and the like are painted in the same color. For example, in the case of image data composed of a series of golf swing frames, the color of the pixels in the background area is changed to the same color while leaving the golf swing area. In FIG. 4, the golf swing portion is the region A, the background region such as landscape is the region B, and the region B portion is painted in the same color. This filling process is performed until there is no more data to be input (step 104). Next, image data composed of the castle area A that has been subjected to the dither processing and the area B that has been filled with the same color is processed by the difference processing unit 1.
3 and a difference process is performed (step 10).
5). Here, the difference data output from the difference processing unit 13 will be described. FIG. 5 is a diagram illustrating the concept of the difference processing. First, the first frame is prepared, this data is stored in the previous frame data storage means 21, and the data of the second frame is prepared. And the inter-frame difference processing means 2
2, the value of the first frame data (previous frame data) stored in the previous frame data storage unit 21 at the same pixel position and the value of the second frame data (current frame data) are excluded. A logical OR is obtained, and this is used as difference data. When the exclusive OR is calculated for all the pixels, the data of the second frame is stored in the previous frame data storage means 21, and the data of the next frame is prepared. This difference processing is performed until there is no more data to be input (step 106).

Then, the data (difference data) supplied from the difference processing means 13 is input to the compression processing means 14 to perform compression processing (step 107). The compression process is performed until there is no more data (step 108). By performing the above processing, the input moving image data has been encoded.

As described above, in the first embodiment, the coding efficiency is improved by painting the non-moving area or the background area in the dithered data with the same color, thereby improving the coding efficiency of the moving image data. The amount of subsequent data can be reduced.

<< Second Embodiment >> According to the above-described first embodiment, it is possible to perform video coding with a small code amount. What is necessary is just to thin out. FIG. 6 shows a moving picture coding apparatus that performs data thinning.

This moving picture coding apparatus has a configuration in which a thinning processing means 15 for performing a thinning processing of moving picture data is added to the input terminal of the moving picture coding apparatus shown in FIG.

First, the thinning processing of moving image data will be described. FIG. 7 is a diagram for explaining the thinning processing. As shown in the figure, when the image data 41 that is continuous in time series is arranged in frame units, the thinning processing unit 15 deletes the image data of the hatched frame. Thereby, the data amount of the input moving image data is reduced to half.

Next, the operation of the moving picture coding apparatus will be described with reference to FIG.

The input moving image data is first input to the thinning processing means 15, where the thinning processing is performed to reduce the data amount (step 111). This thinning process is performed until there is no more data (step 11).
2). The thinned data is input to the dither processing means 11, and dither processing (step 113) is performed on all areas in the frame until there is no more data (step 114). Subsequently, the data subjected to the dither processing is input to the filling processing means 12, and the area with no motion and the background area are filled with the same color by the filling processing (step 115). The painting process is performed until there is no more data (step 116).

In the present embodiment, since the thinning process is performed, the correlation between the frames is lost, and the data amount may be increased by performing the difference process.
Therefore, after executing the filling process, first, it is determined whether or not to execute the difference process (step 117). If there is much data to be thinned out and the correlation between the frames is lost, the process proceeds to step 120 without performing the difference processing, otherwise, the difference processing is performed (step 1).
18). In the difference processing, the data subjected to the filling processing is input to the difference processing unit 13. The difference processing is performed until there is no more data (step 119), and then the process proceeds to step 120.

In step 120, the data is input to the compression processing means 14 and compression processing is performed. The compression process is performed until there is no more data (step 121).
The process ends.

As described above, in the second embodiment, the thinning processing is performed before the dither processing is performed, and the area without motion or the background area in the dither-processed data is painted to reduce the data amount. By performing difference processing according to the nature of the data and then performing compression processing,
The data amount of the moving image data after encoding is further reduced.

<< Third Embodiment >> In the above-described first and second embodiments, the difference processing by the difference processing means 13 is performed at the same display position as shown in FIG. This is a process in which exclusive OR of pixel values is calculated to be difference data. However, when there is little correlation between frames such as thinned data or dithered data, difference processing using exclusive OR may not sufficiently reduce the data amount. Therefore, in the third embodiment,
The difference between the color data of the pixels at the same display position is calculated.

That is, in the moving picture coding apparatus according to the third embodiment, the first moving picture coding apparatus shown in FIGS.
In the moving picture coding apparatus according to the present embodiment and the moving picture coding apparatus according to the second embodiment, a difference processing means 20 having a configuration shown in FIG. This difference processing means 20
Is a previous frame data storage unit 21 for storing the frame data of the previous frame, and a difference value obtaining unit for obtaining a difference value (absolute value) between the color data of the previous frame and the color data of the current frame at the pixel at the same display position. 23, and a threshold input means 24 for inputting and holding a predetermined threshold in advance
And the difference value acquired by the difference value acquiring means 23 and the threshold value held in the threshold value input means 24. If the difference value is smaller, “0” is set. Otherwise, “1” is set. Is output to the compression processing means 14 as differential data.

Hereinafter, the acquisition of the difference value by the difference value acquiring means 23 will be described with reference to FIG. FIG. 10 shows one frame of RGB data of image data (R: red, G: green, B:
Blue), one frame can be decomposed into a plane 51 of R data, a plane 52 of G data, and a plane 53 of B data, and each color data is represented by one bit per pixel. And The acquisition of the difference value is processed in units of three bits of R data, G data, and B data. Now the previous frame's RGB
The data is, for example, [R, G, B] = [1,1,0], and the RGB data in the current frame is, for example, [R, G, B] =
If it is [1,1,1], the difference value is 1. The difference value thus obtained is compared with a threshold value by the difference value comparison means 25, and as a result, difference data is output.

As described above, in the present embodiment, the difference value is obtained based on the color data, and the difference value is compared with the threshold value to generate the difference data. Since a small amount of data is omitted, the encoding efficiency in the compression processing is further improved.

[0050]

As described above, according to the present invention, a part of the image data after the dither processing, typically, a non-moving area or a background area is painted in the same color to obtain the dither data. The area of the area becomes smaller,
This has the effect of reducing the amount of data after encoding and improving encoding efficiency.

Further, by performing the difference processing after painting, data having randomness is converted to data having a long run length, and the data amount after encoding is further reduced. When the difference data is determined by comparing the difference value with the threshold value, the effect of the difference processing is exhibited even for data having a small correlation between the frames,
Since the data of the portion where there is little change between the frame data is omitted, the encoding efficiency in the compression processing is further improved. Furthermore, by performing frame thinning before performing dither processing, the amount of data to be encoded is reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a video encoding device according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a difference processing unit.

FIG. 3 is a flowchart showing a process of the moving picture encoding device of FIG. 1;

FIGS. 4A and 4B are diagrams for explaining a filling process;

FIG. 5 is a diagram illustrating the concept of a difference process.

FIG. 6 is a block diagram illustrating a configuration of a video encoding device according to a second embodiment of the present invention.

FIG. 7 is a diagram illustrating a thinning process.

FIG. 8 is a flowchart showing a process of the moving picture encoding device of FIG. 6;

FIG. 9 is a block diagram illustrating a configuration of a difference processing unit in the video encoding device according to the third embodiment.

FIG. 10 is a diagram illustrating a difference process according to the third embodiment.

FIG. 11 is a diagram illustrating an example of a configuration of a conventional encoding device that encodes a halftone image by a dither method.

FIG. 12 is a diagram illustrating a Bayer-type dither matrix.

FIGS. 13A to 13C are diagrams illustrating examples of binary patterns after dither processing.

FIGS. 14A and 14B are diagrams showing examples of difference patterns.

15A is a diagram showing data at the time of coincidence, FIG. 15B is a diagram showing data at the time of non-coincidence, and FIG. 15C is a diagram showing a correspondence between a non-coincidence location address and a matrix.

FIG. 16 is a block diagram showing a conventional continuous image time series processing system.

FIG. 17 is a block diagram illustrating a configuration of a continuous image compression unit.

FIG. 18 is a conceptual diagram showing a relative relationship among addresses of a first frame memory and a second frame memory, a color data memory, and a display time data memory.

FIG. 19 is a flowchart showing a procedure for performing time-series direction run-length encoding.

FIG. 20A is a flowchart illustrating an initialization process, and FIG.
5 is a flowchart showing output processing by the output control circuit.

FIGS. 21A and 21B are diagrams showing a data structure of data stored in a storage medium, wherein FIG. 21A shows a first frame and FIG. 21B shows a second frame.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 dither processing means 12 fill processing means 13, 20 difference processing means 14 compression processing means 15 thinning processing means 21 previous frame data storage means 22 inter-frame difference processing means 23 difference value acquisition means 24 threshold value input means 25 difference value comparison means

Claims (6)

(57) [Claims] 1. A moving image encoding method for encoding moving image data composed of a plurality of frames, comprising: a dither processing step of performing dither processing on the moving image data; and a moving image subjected to the dither processing. A moving image characterized by comprising: a filling processing step of filling a partial area of the data with the same color; and a compression processing step of performing compression encoding on moving image data that has passed through the filling processing step. Encoding method. 2. The method according to claim 1, further comprising a difference processing step of obtaining difference data between the moving image data of the current frame and the moving image data of the previous frame after performing the filling processing step, wherein the compression processing step is performed based on the difference data. Perform compression encoding,
The moving picture coding method according to claim 1. 3. A moving picture coding apparatus for coding moving picture data composed of a plurality of frames, comprising: a dither processing means for dithering the moving picture data; and one of data output by the dither processing means. A moving image encoding apparatus comprising: a filling processing unit that fills a region of a part with the same color; and a compression processing unit that performs compression encoding based on data output by the filling processing unit. 4. The moving picture coding apparatus according to claim 3, further comprising a thinning-out processing means for thinning out frames of the moving image data input to said dither processing means. 5. A difference processing means for obtaining difference data between moving image data of a current frame and moving image data of a previous frame is provided on an output side of the painting means, and the difference data is inputted to the compression processing means. Claim 3 to be encoded
Or the moving image encoding device according to 4. 6. A difference value acquiring means for acquiring a difference value for each pixel between data of a current frame and data of a previous frame, and a difference value acquiring means for acquiring the difference value and a predetermined threshold value. And a difference value comparing means for comparing to determine difference data, wherein when the difference value is equal to or less than the threshold value, there is no difference between the current frame and the immediately preceding frame for the pixel. The moving picture encoding apparatus according to claim 5, wherein