JPS6128264B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color image encoding processing method, and particularly to an encoding processing method for efficiently transmitting or storing color images.

Conventionally, the DPCM encoding method, for example, is well known as an encoding processing method for transmitting or storing color images, but when one screen of color television is digitally encoded using the DPCM encoding method, one screen is Approximately 1 million to 1.25 million bits per pixel (approximately 4 to 5 bits per pixel)
The amount of data caused a problem in terms of encoding efficiency.

The present invention provides a processing method for highly efficiently encoding a color image whose color types and definition are limited to a certain extent according to the local properties of each area obtained by subdividing the color image. The purpose is to provide detailed explanations using the drawings below.

FIG. 1 schematically shows an example of a color image to which the present invention is applied. An example of the case is shown below. Now, in FIG. 1, the background part 101 of the image is blue, and the triangular part 10
2 is colored red, and the rectangular portion 103 is colored green.

Fig. 2 shows an embodiment of digital encoding of a color image according to the present invention. Fig. 2a shows an area (block) obtained by dividing a color image into predetermined sizes, consisting of pixels of almost the same color. This shows an example of encoding a block (single-color isolated block) in which the color composition of the pixel group in the block is different from the adjacent block. 201 is information indicating that the block is a monochrome isolated block, and 202 is the information indicating that the block is a monochrome isolated block. This is information indicating pixels within a monochromatic isolated block. FIG. 2b shows an example of encoding a block (monochromatic continuous block) in which the block is composed of pixels of almost the same color and the color composition of the pixel group in the block is almost the same as that of the adjacent block. 204 is information indicating the color of the pixels in the monochrome continuous block. 205 is information indicating the number of continuous monochrome blocks. Figure 2c shows an example of encoding a block (multicolor block) in which the block is composed of two or more types of pixel groups with different colors, and 206 is information indicating that the block is a multicolor block. , 207 and 208 are information indicating the color types of two different pixel groups in the multi-color block, and 209 corresponds to the color indicated by the information 207 and 208 in the multi-color block. This information indicates the pixel distribution by color.
FIG. 2d shows another example of encoding the multicolor sub-block, and 201 is information indicating that the block is a multicolor block and that the block is encoded in the format shown in FIG. 2d. , 211 and 21
2 is information indicating the color types of two different pixel groups in the multicolor block, and 213 is information that indicates the pixel distribution by color of the two different pixel groups in the multicolor block. Information indicating which number of pixels among a plurality of predetermined types of pixel numbers indicates the pixel distribution for each color (hereinafter referred to as resolution information); 214 indicates the number of pixels indicated by the information 213; This is information indicating color-by-color pixel distribution (hereinafter referred to as color-by-color pixel distribution information) within the block in units of groups.

Figure 3 shows an example of applying the encoding method shown in Figure 2 to the example image in Figure 1.
Reference numeral 321 in the figure is a background part made up of a group of blue pixels, which corresponds to the encoding 101 shown in FIG. 325 is a rectangular portion consisting of a group of green pixels and corresponds to the reference numeral 103 shown in FIG. Each area (block) when divided into areas is shown. When encoding the image in Figure 3 using the encoding method shown in Figure 2, the third
Blocks 301 and 315 shown in the figure are the second
The blocks 303, 304, and 305 shown in FIG. 3 are encoded in the format shown in FIG. 2b, and the blocks 302, 30 in FIG.
6,307,308,309,310,311,
312, 313, and 314 can be encoded in the format c or d in FIG. 2, respectively.

FIG. 4 is an explanatory diagram illustrating in more detail the case where block 302 of FIG. 3 is encoded in the format of FIG. 2c. Now, the block 302 shown in FIG.
When viewed microscopically, as shown in Figure 4a, a block of 30 pixels is formed by a group of 10 pixels in the horizontal direction and 10 pixels in the vertical direction.
2, and the pixels in the block 302 consist of a blue pixel group 401 and a red pixel group 402. When encoding the block shown in FIG. 4a in the format shown in FIG. 2c, the pixel distribution information 209 for each color in FIG. 2c corresponds to each pixel in FIG. If the color of each pixel is blue, the number 0 is assigned, for example, and if the color of each pixel is red, the number 1 is assigned, and the number strings in FIG. 4b are arranged in a predetermined order. It is possible to encode by setting it.

FIG. 5 is an explanatory diagram for explaining in more detail the case where block 309 in FIG. 3 is encoded in the format shown in FIG. 2d. Block 3 shown in Figure 3
When 09 is viewed microscopically, as shown in Figure 5a, block 3 is formed from a group of 10 horizontal and 10 vertical pixels.
09, and the pixel group within the block 309 consists of a blue pixel group 501 and a green pixel group 502. The block shown in FIG. 5a is a numerical string in which the color of each pixel in FIG. 5a corresponds to the numerical value 0 or 1, as explained in FIG.
It is clear that the code can be encoded in the format shown in FIG. 2c using . However, as shown in FIG. 5c, FIG. 5a is a pixel group of two horizontally and two vertically (hereinafter
(referred to as a unit pixel group) can be regarded as one unit consisting of a blue unit pixel group 503 and a green unit pixel group 504. Therefore, when the block 309 in FIG. 3 is encoded in the format shown in FIG. 2d, the unit pixel group 213 in FIG. 2d consists of two pixel groups in the horizontal direction and two in the vertical direction. The information 214 in FIG. 2d indicates whether the unit pixel group shown in FIG. 5c is a blue unit pixel group 503 or green. Encoding is performed by arranging numerical sequences obtained by associating numerical values 0 or 1 depending on whether the unit pixel group 504 is a unit pixel group 504 in a predetermined fixed order.

FIG. 6 shows an embodiment of the present invention, in which 601 is a block extraction unit that outputs color information of pixels for each block for a given color image, and 602 is a block extraction unit that outputs color information of pixels for each block in a given color image. A block type selection section 603 selects either a block or a multi-color block, and 603 is an encoding section that generates three different types of encoded data according to instructions from the block type selection section. The extraction unit is an image memory 604 that stores image information.
and a block readout unit 605 that instructs the image memory to read out pixel color information for each block.A block type selection unit also includes a color determination unit that determines whether all pixels within the block are monochrome. 6
06, a color comparison section 607 that compares the color state of the immediately previous block with the color state of the block in question, and a color register 608 that temporarily stores the color state of the immediately previous block. , monochromatic encoding 60 that generates the encoded data a shown in FIG.
9, a monochromatic continuous encoding section 610 that also generates encoded data b, and a multicolor encoding section 611 that similarly generates encoded data c or d. Note that 612 is an encoded data memory for storing encoded data.

The operation of this embodiment will be described below.

First, according to instructions from the block reading unit 605,
The image memory 604 outputs a group of color information of pixels corresponding to the first block. The color determination unit 606 determines whether the read color information group is all the same color (single color block), and the result is sent to the color comparison unit 60.
Output to 7. In the case of a monochrome block, the color comparison unit sends an encoding instruction to the monochrome encoding unit 609,
In addition, in the case of a non-monochrome block, the multicolor encoding unit 61
An encoding instruction for 1 is output to encoding section 603. At the same time, whether or not the block is a single color is stored in the color register 608, and if it is a single color, the color and the number of consecutive blocks (=1) are stored in the color register 608. The encoding unit 603 generates the designated encoded data and writes it into the encoded data memory 612.

Thereafter, a color determination unit 606 determines whether the color information group sequentially output from the block extraction unit 601 is a single color or not. If the result is a single color, the color comparison unit 607 compares it with the contents of the color register 608, and if the two are different colors, it outputs a single color encoding instruction, and if the two are the same color, it is written in the color register. A value obtained by adding 1 to the number of continuous colors is added to output a monochrome continuous encoding instruction. At the same time, store the new color and color sequence number in the color register. Further, when the result of the color determination section is a multicolor, a multicolor encoding instruction is outputted, and the fact that it is a multicolor is stored in the color register.

On the other hand, in the encoding section, if the instructed content is monochrome encoding or multicolor encoding, the generated encoded data is written while updating the write address of the encoded data memory, and in the case of monochrome continuous instruction, the encoded data is written while updating the write address of the encoded data memory. The encoded data is written to the same address as last time without updating the write address.

The above steps are executed for the entire image memory.

FIG. 7 shows the encoding process in the embodiment described above in the form of a flowchart. Reference numeral 701 in FIG. 7 is a block extraction process that sequentially extracts information on pixels corresponding to blocks from the given color image information, and 702 is a block extraction process 7.
703 is a color determination process for determining whether the block extracted from 01 is a monochrome block or a multicolor block; 703 is a monochrome/multicolor selection process for selecting the next process based on the determination result in the color determination process 702; 704 70 is an isolated/continuous selection process in which when the extracted block is a single-color block, the next process is selected depending on whether the block immediately before the extracted block is a single-color block of the same color;
5 is a format a encoding process for encoding the block into the format shown in FIG.
Format b encoding process for encoding into the format of Figure b, 70
7 is a format c or d encoding process for encoding the block into the format shown in FIG. This is an end determination process that determines whether or not the process has been completed.

Next, the flow of the encoding processing method according to the present invention will be explained in detail based on FIG.

First, in block extraction processing 701, pixel information in a first block is extracted from a given color image. Next, in color determination processing 702, it is determined whether the block is a single color block or a multicolor block. In the single color/double color selection process 703, color determination process 7
The next processing procedure is selected based on the information of the identification result in step 02. Now, if the block is a multicolor block, in the encoding process 707, it is converted to c or d in FIG.
The block is encoded in the format. Further, if the block is a monochrome block, the next process to be performed is selected in the isolated/continuous selection process 704 depending on whether or not the previous block was a monochrome block of the same color as the block,
If the previous block is a monochrome block of the same color, encoding is performed in the format shown in FIG. 1
Rewrite the encoding information of the previous block as follows. In other words, if the encoding information of the previous block is in the format shown in Figure 2a, it is rewritten to the format shown in Figure 2b (consecutive number information = 2), and the encoding format of the previous block is in the format shown in Figure 2b. If the code is in the format, the consecutive number information 205 of the code is updated. Each of the above encoding principles 7
After 05, 706, 707, end determination processing 70
In step 8, it is determined whether encoding of all blocks of the given color image has been completed based on the information from the block extraction processing procedure in the block extraction processing 701, and if it has not been completed, the block extraction processing 701 is performed. Returns to the process, and if it has finished, cancels the process.

As described above, according to the present invention, it is possible to digitally encode a color image with relatively limited color types and definition with a relatively small amount of numerical string information with high efficiency. Furthermore, when considering the case of encoding by a digital processing device, processing becomes simpler.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram schematically showing an example of a color image targeted by the present invention, FIG. 2 is an example of digital encoding of a color image according to the present invention, and FIG. An explanatory diagram showing an example of region (block) division when applying the above encoding to the color image of FIG. 1, FIG. Figure b is an example of color-specific pixel distribution information when each pixel in Figure 4 a is associated with a different numerical value "0" or "1" for each color, and Figure 5 a is a microscopic image of the area 309 in Figure 3. 5b is an example of pixel distribution information for each color when each pixel in FIG. A schematic diagram of the example image in FIG. 5a when it is considered to be composed of a unit pixel group of 4 pixels consisting of 2 pixels in the horizontal direction and 2 pixels in the vertical direction, and FIG. 5d is a schematic diagram of the example image in FIG. An example of color-specific unit pixel group distribution information when the unit pixel group is associated with different numerical values "0" and "1" for each color, FIG. 6 is an example of the color image encoding processing method according to the present invention,
FIG. 7 shows the processing flow of the embodiment shown in FIG. In the figure, 101 is a background part, 102 is a triangular part,
103 is a rectangular part, 201 to 214 are information, 301 to 315 are blocks, 60
1 represents a block extraction section, 602 a block type selection section, and 603 an encoding section.

Claims (1)

[Claims] 1. In cases where a color image can be considered to be composed of small areas (hereinafter referred to as pixels) each having a single color, the color image is made up of a predetermined approximately constant number of a x b pixels. A block extraction unit subdivides the area into area regions (hereinafter referred to as blocks) and sequentially reads out the color information of the pixels within each block. Each of the blocks is a single-color isolated block with a different color composition of pixel groups, or each block is a single-color continuous block consisting of a pixel group of substantially the same color, and the color composition of the pixel groups within the block is substantially the same as that of the adjacent block. A block type selection section determines whether each block is a multi-color block consisting of two or more types of pixels of different colors, and a block type selection section determines whether the block is a single-color isolated block or a single-color continuous block. and an encoding unit that digitally encodes each multicolor block separately, thereby encoding a color image.