JPS605115B2 - Color image encoding processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color image encoding processing method, and particularly to a color image encoding processing method for digitally encoding a color image and storing it in a digital storage device etc. by arranging it in a small number of bits. be.

- Conventionally, as a coding processing method for storing color images and retrieving them as needed, there is a method that stores color images in the form of a DPCM code, known as a digital code for image transmission, on a digital magnetic disk, for example. However, when one color television screen is digitally encoded using DPCM encoding, the signal for one screen is approximately 100 to 1.25 million bits (
The amount of data is 4 to 5 bits per pixel, which poses a problem in terms of economy.

In order to efficiently store color images whose color types and definition are limited to a certain degree in a digital storage device such as a digital magnetic disk, the present invention is directed to the local characteristics of each area obtained by dividing a color image into pieces. The purpose is to provide a procedure for highly efficient encoding according to the
This will be explained in detail below using the drawings. FIG. 1 is an explanatory diagram schematically showing an example of a color image targeted by the present invention.

The figure shows an example of a color image with relatively few types of colors and a relatively wide area in which the same color continues. In FIG. 1, it is assumed that the background portion 101 of the image is colored blue, the triangular portion 102 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. Figure 2a shows an example of encoding when a color image is divided into predetermined sizes (blocks) that are composed of pixels of almost the same color (hereinafter referred to as monochrome blocks). 201 is information indicating that the block is a monochrome flock, and 202 is information indicating the color of the pixel within the monochrome flock. FIG. 2b shows an encoding example in which a plurality of monochrome blocks are consecutive and each continuous monochrome block is composed of pixels of the same color. Information indicating that a plurality of blocks are consecutive; 204 is information indicating the color of the pixels in each block; and 205 is information indicating the number of consecutive monochrome blocks. Figure 2c shows an example of encoding when a block is composed of two or more types of pixels with different colors (hereinafter referred to as a multicolor block), and 206 indicates that the block is a multicolor block. This is image information in each sub-block obtained by subdividing the block into a predetermined number of sub-blocks, and in the figure, the block is sub-divided into 4 sub-blocks. This shows the case where Figures 2d to 2f show the sub-bums. FIG. 2 is a diagram for explaining in-pack image information in more detail. FIG. 2d shows image information within a subblock when the subblock is composed of pixels of almost the same color (hereinafter referred to as a monochrome subblock).
1 is information indicating that the sub-block is a monochrome sub-block, and 212 is information indicating the color of the pixels within the sub-block. Further, Fig. 2c shows image information within a sub-block when the sub-block is composed of two types of pixels with different colors (hereinafter referred to as a multi-color sub-block), and 213 indicates that the sub-block is composed of two types of pixels with different colors. Information indicating that it is a block, 214 and 215 are information indicating the colors of two types of pixels of different colors in the multi-color sub-block, and 216 is based on the information 214 and 215 of the pixels in the multi-color sub-block. This is information indicating color-specific pixel distribution corresponding to the displayed color. Furthermore, FIG. 2f shows another example of the image information in the multi-color sub-block.
17 is information indicating that the sub-block is a multi-color block and that the image information within the sub-block is encoded in the information format f; 218 and 219 are two types of different colors within the multi-color block; information indicating the color of the pixel,
220 indicates the pixel distribution by color of two types of pixels of different colors in the relevant subsequent color block, and information indicating which number of the predetermined number of types is used as a unit to indicate the pixel distribution by color. (hereinafter referred to as resolution information), 221 is information indicating the pixel distribution by color in the multicolor sub-block in units of the number of pixels indicated by the resolution report 220 (hereinafter referred to as unit pixel group distribution information by color) represents. FIG. 3 is an explanatory diagram showing an example of the case where the encoding method shown in FIG. 2 is applied to the image example shown in FIG. 1.

301 to 312 indicate each region (block) when the image of FIG. 1 is divided into regions of a predetermined constant size, 103 is a background portion consisting of blue pixels corresponding to FIG. 1, and 102 is a A triangular portion 103 is made up of a red image corresponding to FIG. 1, and a rectangular portion 103 is made up of green pixels corresponding to FIG.

If the image in FIG. 1 is to be encoded using the encoding method shown in FIG. 2, the block 301 in FIG.
Flocks 303 to 305 are encoded in the format shown in FIG.
6,307,308,309,310,311,312
can be encoded in the format shown in FIG. 2c, respectively.
FIG. 4 is for explaining in more detail the implementation method when the block 311 in FIG. 3 is encoded in the format shown in FIG. 2c. 10 shall be subdivided into sub-blocks 401 to 404.
1 shows a part of the blue background part in FIG. 3, 102 shows a part of the red triangular part, and 103 shows a part of the green rectangular part. B in Figure 3. When the block 311 is encoded in the format shown in FIG. 2c, the first sub-block 401 in FIG.
The image information section 207 of the second sub-block 402, and the image information section 210 of the fourth sub-block 404 perform encoding in the format shown in FIG. 2c or f, respectively. The image information section 209 of the subblock 403 can be encoded in the format shown in FIG. 2d. FIG. 5 is an explanatory diagram for explaining in detail the case where the sub-block 401 of FIG. 4 is encoded into the format of FIG. 2 e. If we look at the sub-block 401 in Fig. 4 microscopically, it is composed of 8 pixels in the horizontal direction and 8 pixels in the vertical direction, as shown in Fig. 5a, where 501 is a red pixel group and 502 is a blue pixel group. Suppose that it shows a group of pixels. When the sub-block of FIG. 5a is encoded in the format of FIG. 2e, the color-specific pixel distribution information 216 of FIG.
If each pixel is red, a value such as "0" is associated with each pixel, and if each pixel is blue, a value such as "1" is associated with each pixel, and the numerical value strings in FIG. 5b are arranged in a predetermined arbitrary order. It can be encoded by keeping it. At this time, Fig. 2 e color information section 2
14 and 215 are encoded with information representing red and blue, respectively. FIG. 6 is an explanatory diagram for explaining in detail the case where the sub-block 402 of FIG. 4 is encoded in the format of FIG. 2 f.

If we look at the sub-block 402 in Fig. 4 microscopically, the sixth
As shown in FIG. a, it is composed of eight pixels in the horizontal direction and eight pixels in the vertical direction, and 601 indicates a blue pixel group and 602 indicates a green pixel group. The sub-block 402 shown in FIG. 6a is constructed by using a numerical string in which "0" or "1" is associated with each pixel in FIG. 6a in the same way as explained in FIG. It is clear that it can be encoded in the form of

However, as shown in Fig. 6b, Fig. 6a shows 4 pieces in the horizontal direction;
With four vertical pixel groups as one unit (hereinafter referred to as a unit pixel group), it can be considered to be composed of a blue unit image group 603 and a green unit pixel group 604. Therefore, when the sub-block 402 in FIG. 4 is encoded in the format shown in FIG. 2 f, the resolution information 22 in FIG. Similarly, in the color unit pixel group distribution information 221, as shown in FIG. 6c, a numerical string corresponding to whether the unit pixel group in FIG. 6b is blue or green is predetermined. It can be encoded by filling in any order. In this way, although it is applied when the target image has two types of colors in one block in the case of the above embodiment, it is possible to digitally encode a color image with a small amount of data. .

Note that it is optional to allow one block to have three or more colors by providing generality. FIG. 7 shows an embodiment of the present invention in the form of a flowchart.

In FIG. 7, numeral 701 represents a block extraction unit that sequentially extracts pixel information corresponding to blocks from a given color image and identifies the end of encoding processing of the given image. 702 is a block extraction unit 701
represents a block type determination unit that determines whether the block extracted by is a monochrome block or a multicolor block.

Reference numeral 703 represents a block state selection unit that selects the next process based on the state of the block before the block extracted by the block extraction unit 701, when the block is a monochrome block.

Reference numeral 704 represents a monochrome block a encoding unit that encodes intra-block pixel information in the format shown in FIG. 2a.

Reference numeral 705 represents a monochrome block b encoding unit that encodes the pixel information within a block group in the format shown in FIG. 2b.

Reference numeral 706 denotes a multi-color block state selection unit that selects the next process based on the state of the block before the block extracted by the block extraction unit 701 when there are a plurality of blocks.

Reference numeral 707 represents a monochrome block a encoding unit that encodes the block inner element information in the format shown in FIG. 2a.

Reference numeral 708 represents a monochrome block b encoding unit that encodes the block group intra-block national element information in the format shown in FIG. 2b.

709 is a subblock that subdivides a given block into subblocks of a predetermined size, sequentially extracts pixel information within the subblocks, and identifies the end of encoding processing for all subblocks within the given block. Represents the extraction part.

Reference numeral 710 represents a sub-block type determining unit that determines whether the sub-block extracted by the sub-block extracting unit 709 is a monochrome sub-block or a multi-color sub-block.

Reference numeral 711 represents a monochromatic subblock d encoding unit that encodes subblock internal element information in the format shown in FIG. 2d.

Reference numeral 712 represents a multicolor subblock e or f encoding unit that encodes the pixel information within the subblock in the format shown in FIG. 2 e or f.

Reference numeral 713 represents a dark blue block c encoding unit that encodes the pixel information within the block in the format shown in FIG. 2c.

The encoding processing method according to the present invention will be explained below based on FIG.

First, a block extraction unit 701 extracts pixel information in a first block from a given color image.

Next, a block type determining unit 702 determines whether the block is a monochrome block, and if the block is a monochrome block, the processing is passed to the block state selection unit 703, and if it is a multicolor block, the process is passed to the multicolor block state selection unit 706. For example, in the case of a monochrome block, the block state selection unit 703
The color information of the block is stored and processed by the block extraction unit 7.
Return to 01. A block extraction unit 701 extracts pixel information within the second block, and a block type determination unit 702 determines whether or not it is a monochrome block. If the second block is also a monochrome block, the flock state selection unit 703 compares the color information of the first block and the color information of the second block, and if they are the same, a monochrome block of the same color as this color information is selected. The block extraction unit 701 stores the number of consecutive pieces and performs processing.
Return to On the other hand, if the color information of the second block is different from the color information of the first block, the color information of the second block is stored and the process is passed to the monochrome block a encoding unit 704.
The monochrome block a encoding unit 704 encodes the pixel information in the first block into the format shown in FIG. Return to extraction section 701. Thereafter, the same process is repeated, and if the block extracted by the block extraction unit 701 is determined to be a monochrome block by the block type determination unit 702, the block state selection unit 7
03 stores the color information of the block and returns the process to the block extraction unit 701 if the encoding process for the block before the block has been completed. Also, if the encoding process for the block before this block has not been completed,
The color information of the immediately preceding block is compared with the color information of the block, and if they are the same, the process is returned to the block extraction unit 701, and if they are different, the process is passed to the monochrome block encoding unit 704 or 705 depending on the number of unprocessed blocks. . In other words, if there is one unprocessed block, it is determined that it is an independent single-color block and the processing is passed to the encoding unit 704, and if there are multiple unprocessed blocks, these blocks are of the same color and are continuous. It is determined that it is a monochromatic block group, and processing is passed to the encoding unit 705. As described above, encoding is performed when the block extracted by the flock extraction unit 701 is a monochrome block. On the other hand, a case will be described below in which the block extracted by the block extraction unit 701 is determined to be a multicolor block by the block type determination unit 702 and processing is passed to the multicolor block state selection unit 706. The multicolor block state selection section 706 performs the same processing as the monochrome block state selection section 7083. That is, if the encoding process for the block preceding the block extracted by the block extracting unit 701 and determined to be a multicolor block by the flock type determining unit 702 has been completed, the processing is passed to the sub-block extracting unit 709. Further, if the encoding process for the block before this block has not been completed, and there is only one block that has not yet been encoded, this is regarded as an independent monochrome block and the process is passed to the monochrome block a encoding unit 707, When there are a plurality of blocks that have not yet been encoded, they are regarded as a continuous single-color block group of the same color, and processing is passed to the single-color block b encoded product 708. The encoding unit 707 encodes the data into the format shown in FIG. 2a, and the encoding unit 708 encodes it into the format shown in FIG. The saff lock extraction unit 709 further subdivides the block determined to be a maroon block by the block type determination unit 702 into subblocks of a predetermined size,
Pixel information within sub-blocks is sequentially extracted. Next, a sub-block type determination unit 710 determines whether this sub-block is a monochrome sub-block or a multi-color sub-block, and if the sub-block is a monochrome sub-block, a monochrome sub-block d encoding unit 71
1, and in the case of a multicolor subblock, the processing is passed to the multicolor subblock e or f encoding unit 712. The encoding unit 711 converts it into the format shown in FIG. 2d, and the encoding unit 712
Then, the data is encoded in the format shown in e or f in FIG. From then on,
Continuing similar processing, when the encoding processing for all sub-blocks is completed, the sub-block extracting unit 709 passes the processing to the multi-color block c encoding unit 713, and the encoding unit 7
In step 13, based on the plurality of intra-subblock pixel information encoded by the encoding unit 711 or 712,
The pixel information in the block determined to be a yellow block by the block type determining unit 702 is encoded into the format shown in FIG. 2c, and the processing is returned to the block extracting unit 701. When the encoding process for all blocks is completed as described above, the block extraction unit 701 stops the process, and the encoding process of this embodiment ends.

As explained 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, and also it is possible to digitally encode a color image with relatively limited color types and definition. A relatively simple configuration is sufficient for the encoding process, and it is also possible to apply a device developed using a digital computer, for example, if necessary.

Another advantage is that a storage device for digitally encoding and storing color images can be realized economically.

[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 encoding format showing an embodiment of digital encoding of a color image in the present invention, and FIG. The figure is an explanatory diagram showing an example of region division when the encoding method shown in Fig. 2 is applied to the color image example of Fig.
An explanatory diagram showing an example of division in which one area divided in the figure is further subdivided into subblocks, FIG. 5 a is an explanatory diagram when the subdivided area in FIG.
Fig. 5b is an explanatory diagram illustrating the color-by-color map distribution information in which each pixel in Fig. 5a is associated with a different numerical value "0" or "1" for each color. Similarly to the case, FIG. 6b is an explanatory diagram when the subdivided area in FIG. 4 is further microscopically divided, and FIG.
An explanatory diagram illustrating the case where pixels are considered to be composed of unit pixel groups, and FIG. 6 c is a case where the unit pixel groups in FIG. 6 b are associated with different numerical values ``0'' and ``1'' for each color. FIG. 7 is an explanatory diagram illustrating color drama pixel group distribution information, and FIG. 7 shows an embodiment of the color image encoding processing method according to the present invention in the form of a flowchart. In the figure, 101 is a background part, 102 is a triangular part, 103 is a quadrilateral part, 301 is not provided, 312 is a block, and 401 is a rectangular part.
404 are sub-blocks, 701 is a block extraction unit, 702 is a block type discrimination unit, 703 is a block state selection unit, 704 and 707 are each a monochrome block a coded product, 705 and 708 are each a monochrome block b coded product,
706 is a multi-color block state selection section, 709 is a sub-block extraction section, 7101 is a sub-block type discrimination section, 711
712 represents a monochrome subblock d encoding unit, 712 represents a multicolor subblock e or f encoding unit, and 713 represents a multicolor block c encoding unit. Younger brother l figure connection Z figure figure 3 ※ 4 figure ※ 5 figure 6 figure 7

Claims (1)

[Claims] 1 A color image is subdivided into areas of a predetermined size (hereinafter referred to as blocks), and a first block consisting of a group of pixels having almost the same color is divided into multiple consecutive blocks of the same color. a block state selection unit that separates and extracts a second block group when the pixel is selected and a third block that is made up of two or more types of pixel groups with different colors; The third block is further subdivided into regions of predetermined size (hereinafter referred to as sub-blocks), and the third block is further subdivided into regions of predetermined size (hereinafter referred to as sub-blocks). A sub-block type discriminating unit separates and extracts a first sub-block consisting of a group of pixels having the same color and a second sub-block consisting of two or more types of pixel groups having different colors, and a selection is made by the sub-block type discriminating unit. 1. A color image encoding processing method, comprising: a subblock encoding section for digitally encoding said subblocks.