Facsimile and static presentation processing – Natural color facsimile – Specific image-processing circuitry
Patent
1996-03-12
2000-10-31
Coles, Edward L.
Facsimile and static presentation processing
Natural color facsimile
Specific image-processing circuitry
3582612, 3582614, 358426, 358448, 358460, 358524, 358500, 382162, 382165, 340 63, 340 64, 340 95, 345153, 345154, 375253, H04N 1411, H04N 146, G06K 936
Patent
active
061411221
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a data compressing method for compressing image data containing color data, an image data memory for storing the compressed image data, a method and a device for expanding the image data.
BACKGROUND ART
The conventional image data processing equipment comprises a color RAM which holds a number of color information to be used, and an object data memory which holds object data which holds address information of the color RAM.
FIGS. 12A to 12C show memory maps of the object data memory and the color RAM of the conventional image data processing equipment. The maps comprise a bitmap of 8 successive pixels for respective colors A-H as shown in FIG. 12A, a color RAM which holds RGB data of the colors A-H (FIG. 12C), and an object data memory which holds address information (0-7) of the color RAM (FIG. 12B).
The color RAM of FIG. 12C is accessed based on addresses held by the object data memory of FIG. 12B to output color information of the object data held by the object data memory.
Such conventional image data processing equipment needs, as the object data memory, a large capacity memory having capacities for a number of pixels on the bitmaps. This hinders downsizing of the equipment and cost reduction. This is a problem.
An object of the present invention is to provide a data compressing method which can efficiently compress image data containing color data.
Another object of the present invention is to provide an image data memory which can efficiently compress image data containing color data and store the compressed image data.
A further another object of the present invention is to provide a compressed data expanding method and system which can quickly expand compressed data on a bitmap.
DISCLOSURE OF INVENTION
The image data compressing method according to one aspect of the present invention is characterized in that image data containing color date are compressed into image data including: address fields which hold addresses of color information storage means holding color information, the address corresponding to the color data; classification fields which, when the color information storage means are classified in prescribed categories, hold classification information of the category in which the color data are included; and run length fields which hold numbers of successive repetitions of color data. Image data containing color data can be efficiently compressed.
In the above-described image data compressing method, it is preferable that, when the address fields have a large bit number, the run length fields have a decreased bit number, so that the image data have a fixed length. Compressed image data can be stored in the memory efficiently and compactly.
In the above-described image data compressing method, it is preferable that the categories in which the color information storage means are classified are determined in accordance with frequencies of use of the color information. Color data with a high frequency of use can be compressed, so that an overall higher data compression ratio can be obtained.
In the above-described image data compressing method, it is preferable that the image data further includes cell fields which indicate whether or not all pixels of a cell which is a processing unit for writing have the same color. Image data containing color data can be more efficiently compressed.
The image data memory according to one aspect of the present invention is characterized in that the image data memory comprises: address regions which hold addresses of color information storage means holding color information, the address corresponding to the color data; classification regions which, when the color information storage means are classified in prescribed categories, hold classification information of the categories in which the color data is included; and run length regions which hold numbers of successive repetitions of color data. Image data containing color data can be efficiently compressed to be stored.
In the above-described image d
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Coles Edward L.
Sega Enterprises Ltd.
Wallerson Mark
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