Method for deciding color number and representative color value based on picture quality limiting condition

A technology representing color and restriction conditions, applied in electrical components, image communication, etc., can solve the problems of too few calculations, low compression rate of text and line image areas, and cost, and achieve the effect of improving the compression rate

Inactive Publication Date: 2010-02-17
NANJING UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The use of JPEG-like methods to compress text will greatly affect the image quality.
[0009] Insufficiency of the existing technology: when the number of colors in the text and line image area is large, the number of colors calculated by different color number calculation algorithms is different, and there is a problem that the number of colors is calculated too much or too little
When the number of colors is calculated too little, the color of text and line images will be miscalculated to produce a strong visual distortion effect; when the number of colors is calculated too much, it may be misidentified as a continuous tone image area and used JPEG-like compression method to compress
Even if it is recognized as a PNG type image area and compressed using a PNG type of compression method, although the quality problem of the text and line image is solved, on the one hand, the compression ratio of the text and line image area will become low, on the other hand When printing a subtractive color image in which the number of colors is overcounted, there will be problems such as consuming more printing ink

Method used

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  • Method for deciding color number and representative color value based on picture quality limiting condition
  • Method for deciding color number and representative color value based on picture quality limiting condition
  • Method for deciding color number and representative color value based on picture quality limiting condition

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no. 1 approach

[0047] The best embodiment will be described below with reference to the diagrams.

[0048] (1) The composition of the image processing system

[0049] figure 1 The configuration of the image processing system related to the present invention (hereinafter referred to as system.) is shown. . As shown in this figure, the system consists of an image processing device 1 , an image reading device 2 connected to the image processing device 1 , an external storage device 3 , and an output device 4 .

[0050] The image reading device 2 is a recognized image reading device that reads a document in units of pages. After the image is read, the image is sent to the image processing device 1 .

[0051] The image processing apparatus 1 is constituted by a computer processing system. Accept the image data managed by the image reading device 2, take the page as a unit, discriminate the text image area, line image area, and natural image area for the received image data, and discriminate t...

no. 2 approach

[0098] One embodiment of the present invention has been described above. In addition, the present invention is not limited to the above implementation manners, and the following parallel processing implementation manners may also be adopted.

[0099] Such as Figure 4.7 The parallel processing implementation of the color number and representative value calculation of the region discrimination processing is shown. As shown in the figure, according to each drawn rectangular area, it first enters the initial color number estimation process S4900, and the color number estimation S4910 can be calculated using the algorithm of the color histogram (as described in the first implementation method). After the number of colors is estimated, enter the candidate color number generating process S4910 to generate a candidate color number instance. After that, enter the parallel processing module according to the number of candidate colors. The parallel processing module includes represen...

no. 3 approach

[0103] The above mentioned the application in the field of compound file compression. In the application of image printing / copying, by accurately calculating the number of colors in the image, within the distortion range acceptable to subjective vision, it is possible to print / copy high-quality images with a small amount of ink. High-quality paper documents. Such as Figure 5 As shown, the image passed figure 1 After the image reading device 2 reads the image, it enters image preprocessing S5000, where the preprocessing mainly replaces the unreproducible colors in the image output device 4 with reproducible colors. The detailed description is described in Japanese Patent Document 4 (see [Japanese Patent Document 4] JP-A-2007-281826). As long as it does not deviate from the gist of the present invention, there is no particular limitation on the specific implementation method of pretreatment.

[0104] After the preprocessing S5000 is completed, enter the image color number ca...

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Abstract

The invention relates to a method for deciding color number and a representative color value based on a picture quality limiting condition. In the method, an image processing method which is characterized by having an initial color estimating means, a representative color value calculating means, a picture quality evaluating means and a color number adjusting means is adopted; in the step of calculating the representative color value, image processing equipment comprises a control module, input equipment and display equipment which are used for processing images, wherein a controller comprisesan interface module, an image preprocessing module, a region demarcation part, a region distinguishing module, a compression module and a compound document generating module. The image preprocessingmodule is used for receiving image data, preprocessing the data and then sending the data to the region demarcation module; the region demarcation module is used for generating the data read from theimage preprocessing module into communicated rectangular regions; the region distinguishing module is used for evaluating the picture quality and distinguishing a character/line region and a continuous tone image region according to the image data of the communicated rectangular regions; and the compression module is used for compressing by different compression methods according to distinguishingresults.

Description

1. Technical field [0001] The invention relates to content and mainly focuses on solving problems such as the calculation of color numbers and representative color values ​​in the field of image processing. The present invention selects the most suitable compression method for the image area by accurately calculating the color number of the image area; accurately calculates the color number and representative color value of the text and line image area so as to improve the compression rate of the text and line image without distortion ;Print high-quality images using less printing ink by accurately calculating the number of colors and representative color values ​​of an image or image area. 2. Background technology [0002] The number of colors is one of the important basis for judging image area compression methods (continuous tone lossy compression like JPEG or discontinuous tone lossless compression like PNG), and the most suitable compression can be selected by accuratel...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04N1/56H04N1/41
Inventor 龚如宾潘金贵
Owner NANJING UNIV
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