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Low-illumination image processing method and device

  • US 10,424,054 B2
  • Filed: 06/26/2015
  • Issued: 09/24/2019
  • Est. Priority Date: 06/26/2015
  • Status: Active Grant
First Claim
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1. A low-illumination image processing method, comprising:

  • inputting a low-illumination image;

    dividing the low-illumination image into different texture regions, calculating a local standard deviation and a gradient sum of the gray scale of pixel points in various texture regions, and calculating a ratio of the local standard deviation and the gradient sum as a texture and noise level parameter of the image;

    performing inverse color processing on the low-illumination image to obtain an inverse color image;

    determining a first filtering coefficient and a second filtering coefficient according to the mean of the standard deviations of the gray scale of pixel points in various texture regions, and performing smoothing processing on an inverse color image by adopting the first filtering coefficient and the second filtering coefficient to obtain a first smoothing image and a second smoothing image respectively;

    performing weighted averaging on the first smoothing image and the second smoothing image according to the texture and noise level parameter to obtain a weighted image;

    calculating a dark channel image of the weighted image, and estimating an environment illumination intensity according to the dark channel image;

    calculating a contrast enhancement coefficient according to the dark channel image and environment illumination intensity;

    calculating a gradient image of the inverse color image, and extracting texture structure from the gradient image of the inverse color image to obtain a texture image;

    combining the texture image with the weighted image to obtain a sharpened image; and

    performing contrast enhancement on the sharpened image according to the environment illumination intensity and the contrast enhancement coefficient to obtain an enhanced image; and

    performing inverse color processing on the enhanced image to obtain an output image.

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