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

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...

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

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