Method and device for evaluating image contrast
An image comparison and evaluation device technology, applied in the field of image processing, can solve the problems of complex calculation, lack of local information acquisition, and insufficient evaluation, and achieve the effect of accurate evaluation results, simple and convenient calculation, and rich image information and pixel information
Active Publication Date: 2022-07-26
KEY & CORE TECH INNOVATION INST OF THE GREATER BAY AREA
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The existing image contrast calculation method is mainly based on the gray level difference between adjacent pixels, combined with the pixel distribution probability under the preset gray level difference, to evaluate the contrast of the image, but this method is complex to calculate and only pays attention to the whole image. The image lacks the acquisition of local information, resulting in insufficient evaluation
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[0037] Please refer to figure 1 , figure 1 A method for evaluating image contrast provided by an embodiment of the present invention includes steps S1 to S4, wherein,
[0038] In step S1, the image to be evaluated is converted into a grayscale image, and the grayscale average value of the grayscale image is calculated.
[0039] In this embodiment, the prior art generally calculates the image contrast in the following manner:
[0040] ;
[0041] where C is the contrast of the image, is the grayscale difference between adjacent pixels, That is, the pixel distribution probability that the grayscale difference between adjacent pixels is δ. But this method usually only pays attention to the whole image and lacks local information. When some parts of the image contain some special information, it is easy to lose these special information in the evaluation by this method; moreover, this method only focuses on the global and ignores the local part, which will lead to the cal...
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The present invention provides a method and device for evaluating image contrast. The method includes: converting an image to be evaluated into a grayscale image, and calculating an average grayscale value; and taking a pixel whose grayscale value is equal to the average grayscale value as a boundary The grayscale image is divided into several areas; the maximum D8 distance from the pixel with the largest gray value in the area to each pixel in the area is used as the area radius of each area, and the change value of each area is combined to calculate the value of each area. Local contrast: According to the local contrast of each area, the global contrast of the image to be evaluated is obtained, and then the evaluation result is obtained. Compared with the prior art, by dividing the image into several areas and calculating the local contrast of each area, the local information of the image is obtained for global evaluation, and the global information of the image and the local information of each part of the image are taken into account while obtaining the image contrast. Improve the fineness of the evaluation and maintain the integrity of the local information of the image.
Description
technical field [0001] The invention relates to the field of image processing, in particular to a method and device for evaluating image contrast. Background technique [0002] In the field of image processing, the evaluation of image quality has always been an important issue that has received widespread attention. The evaluation of image quality can be divided into subjective image quality evaluation methods and objective image quality evaluation methods. The difference is that the former is participated in and artificially subjectively scores the images. Evaluate. The latter uses computer algorithms to evaluate the quality of full reference images, semi-reference images or no reference images. The existing image contrast calculation method is mainly based on the grayscale difference between adjacent pixels, combined with the pixel distribution probability under the preset grayscale difference, to evaluate the contrast of the image, but this method is complicated to calc...
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IPC IPC(8): G06T7/00
CPCG06T7/0002G06T2207/10024G06T2207/30168
Inventor 刘才钰李雪峰吴清泉杨军红刘浩
Owner KEY & CORE TECH INNOVATION INST OF THE GREATER BAY AREA