Histogram local image contrast enhancing method and histogram local image contrast enhancing device

Abstract

The invention relates to a histogram local image contrast enhancing method and a histogram local image contrast enhancing device. After the histogram distribution of one image or video image is obtained, a gray space of a non-key-brightness region of a histogram is compressed by adopting a mode of selecting the brightness range, so that the pixel of the non-key-brightness region is extruded to a small range; the pixel in a key-bright region can obtain a greater brightness gray value equalization space; then, the gray range of an image key block is expanded through specific HS (Histogram Stretching) based method or HE (Histogram Equalization) based method technology; more obvious contrast enhancing and image sharpness improving effects can be obtained; and the problem of distortion of contents of the whole image due to simultaneous distribution out-of-balancing of the brightness gray value of the pixel in other regions of the image or the video image when the brightness gray value of a local part of the whole image or the video image needs to be enhanced in the prior art is solved.

Description

technical field [0001] The invention relates to a device for enhancing image contrast, in particular to a device for expanding the histogram range of a local image to enhance image contrast. Background technique [0002] The contrast of existing single images (photos) or continuous images (movies) plays a very important role in distinguishing the quality of the image by the human eye. If the shooting environment is not ideal, the contrast of the obtained images may be insufficient, resulting in overall In order to solve the problem of insufficient image contrast in the case of tired image performance, various contrast enhancement algorithms have emerged as the times require. [0003] Using the expansion of image contrast can make the image have a stronger visual experience, thereby achieving the purpose of improving image clarity. The function of the gray level of the common gray level histogram (Histogram) is to reflect the number of occurrences of pixels in each gray leve...

AI Technical Summary

Problems solved by technology

[0034] As mentioned above, the existing image contrast enhancement technologies focus on redistributing the entire image according to the brightness grayscale value of each pixel. When the brightness grayscale value distribution of image pixels is obviously unbalanced, it is necessary to locally enhance its brightness. If the grayscale value is processed by the existing contrast enhancement technology, the enhancement effect will be limited, and the content of the entire image will be distorted. Therefore, the main purpose of the present invention is to provide a method and device for contrast enhancement of a histogram local image. By selecting the brightness range, the grayscale space of the non-key brightness area is compressed, so that the pixels in the non-key brightness area are squeezed into a small range, and the pixels in the key brightness area can obtain a larger brightness gray-scale value equalization space, and then Through specific HS or HE technologies, the gray scale value range of the key areas of the image is expanded to achieve more obvious effects of contrast enhancement and image clarity, and solve the problem of partially enhancing the brightness gray scale value of the entire image. The distribution of brightness and grayscale values ​​​​of the pixels in the area is unbalanced, which causes the content of the entire image to be distorted.

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