Adaptive enhancement method for image with uneven brightness

Abstract

The invention discloses a self-adaptive enhancement method for an image with uneven brightness. The method comprises the following steps: converting a color space of an original image; respectively enhancing an illuminance component and a reflection component of image brightness; correcting the brightness component, reasonably combining the corrected illuminance component and the original illuminance component in a spatial domain, and realizing adaptive correction of the contrast component, wherein the brightness value of a bright pixel is not excessively changed while the brightness value ofthe dark pixel is increased, and adaptive enhancement of an image with non-uniform brightness is realized. The method not only can improve the brightness of the dark area of the image, but also can keep the brightness of the bright area of the image stable, has no color distortion after image enhancement, and has strong universality.

Description

technical field [0001] The invention relates to the field of image processing, in particular to an adaptive enhancement method for images with uneven brightness. Background technique [0002] With the popularization of the application of image acquisition equipment, people also have higher requirements for the quality of the collected images. Environmental factors are one of the main factors affecting image quality. The environment with uneven illumination may cause the images collected by the image acquisition equipment to appear Problems such as uneven brightness and color distortion directly affect the development of computer vision, such as difficult extraction of image features and unclear target recognition. Therefore, it is necessary to improve the quality of images with uneven brightness. [0003] In recent years, the method of adaptive enhancement for images with uneven brightness has become a key research direction of various universities. Among them, the algorithm...

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Problems solved by technology

[0002] With the popularization of the application of image acquisition equipment, people also have higher requirements for the quality of the collected images. Environmental factors are one of the main factors affecting image quality. The environment with uneven illumination may cause the images collected by the image acquisition equipment to appear Problems such as uneven brightness and color distortion directly affect the development of computer vision, such as difficult extraction of image features and unclear target recognition. Therefore, it is necessary to improve the quality of images with uneven brightness

[0003] In recent years, the method of adaptive enhancement for images with uneven brightness has become a key research direction of various universities. Among them, the algorithm related to histogram equalization is to enhance the entire image, which will lead to the image that does not need to be enhanced. Regional information is lost, therefore, the algorithm related to histogram equalization is only suitable for images with uniform brightness changes

Algorithms related to gamma correction increase image contrast by adjusting the ratio of high-frequency and low-frequency pixels in the image. This type of algorithm has weak adaptive ability and is prone to over-enhancement and under-enhancement problems.

For example, Liu Zhicheng and others used a two-dimensional gamma function to enhance images with uneven illumination, which has greatly improved the color and quality of the image, but the effect on areas with high brightness in the image is poor, and it is not universal ( Liu Zhicheng, Wang Dianwei, Liu Ying, Liu Xuejie. Adaptive Correction Algorithm for Uneven Illumination Images Based on Two-dimensional Gamma Function[J]. Journal of Beijing Institute of Technology, 2016,36(02):191-196+214.)

The related algorithm of wavelet transform can highlight the detailed information of the image at different scales, but it cannot reduce the image noise and the time complexity of the algorithm

The existing multi-scale Retinex algorithm will produce image color distortion and image quality degradation when enhancing the image; therefore, in the technology of adaptively enhancing images with uneven brightness, the existing algorithms have certain deficiencies, so It is necessary to propose a method with strong universality and without loss of image quality

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