Method for Improving the Contrast of Low Illumination Images

Abstract

A method for improving the contrast of a low-illumination image, comprising the following steps: A, adaptive brightness enhancement: calculate the area of ​​the image histogram, then judge whether the image needs to be enhanced according to the line sequence of the line array image, and adaptively pull the histogram area B. Adaptive contrast enhancement: select the pixel to be processed as the central pixel, calculate the brightness mean value M and variance б of the neighborhood around the central pixel, and then use the variance and mean value to calculate the gray value of the current point, and use the calculated The new gray value replaces the previous gray value; C. Noise suppression: use a filter to perform Poisson denoising on the noise in the image. It can effectively enhance low-illumination-low-contrast images, so that images collected under low illumination can be used for data analysis and identification. Simultaneously, because the algorithm adopted by the present invention is simple, real-time processing of large images can be realized.

Description

technical field [0001] The invention relates to the technical field of image processing, in particular to a method for improving the contrast of low-illuminance images. Background technique [0002] Lighting environment is an important factor affecting image quality. Especially in low-light environments, due to the low illumination of the environment, the light source of the line scan camera cannot be fully exposed, resulting in a relatively low image contrast. In order to increase the brightness of the image, most line scan cameras will increase the brightness of the image by increasing the exposure, increasing the gain, etc., hoping to achieve the purpose of enhancing the contrast and visually improving the image quality. However, no matter increasing the exposure or increasing the gain, the quality of the image will be degraded. Increasing the exposure will blur the moving image, and increasing the gain will increase the dark current noise in the image. As a result, im...

AI Technical Summary

Problems solved by technology

However, either increasing the exposure or increasing the gain will degrade the image quality

Increasing the exposure will blur the moving image, increasing the gain will increase the dark current noise in the image

Therefore, images captured in low-light environments will generally have low brightness, low contrast, and high noise levels

We call this low-illuminance-low-contrast image an image with low brightness, low contrast, and high noise level taken in such a low-illuminance environment, such as figure 1 As shown, this low-illumination-low-contrast image is difficult to meet the requirements of image recording and analysis

Images