Method and apparatus for adjusting image brightness

Patent metadata

Field	Value
Publication number	US-10074164-B2
Application number	US-201715786049-A
Country	US
Kind code	B2
Filing date	Oct 17, 2017
Priority date	Jan 23, 2013
Publication date	Sep 11, 2018
Grant date	Sep 11, 2018

Abstract

Provided are a method and an apparatus for adjusting image brightness. The method includes: acquiring a single-channel brightness image based on grayscales of each channel of an image to be processed; performing Gaussian filtering on the single-channel brightness image to acquire a Gaussian filtered image; adjusting grayscales of the Gaussian filtered image based on the grayscales of the Gaussian filtered image and a preset proportion; acquiring a grayscale change rate of each pixel with respect to the Gaussian filtered image after adjustment and the Gaussian filtered image before adjustment; and processing the image to be processed based on the grayscale change rate of each pixel to acquire a processed image.

First claim

What is claimed is:

1. A method for adjusting image brightness, comprising:
acquiring a single-channel brightness image based on grayscales of each channel of an image to be processed;
performing Gaussian filtering on the single-channel brightness image to acquire a Gaussian filtered image;
adjusting grayscales of the Gaussian filtered image based on the grayscales of the Gaussian filtered image and a preset proportion;
acquiring a grayscale change rate of each pixel with respect to the Gaussian filtered image after adjustment and the Gaussian filtered image before adjustment; and
processing the image to be processed based on the grayscale change rate of each pixel to acquire a processed image.

2. The method according to claim 1 , wherein the acquiring the single-channel brightness image based on grayscales of each channel of the image to be processed comprises:
comparing grayscales of respective channels of each pixel of the image to be processed; and
determining a maximum value from the grayscales of respective channels of each pixel as a grayscale of each pixel, to obtain the single-channel brightness image.

3. The method according to claim 1 , wherein the adjusting grayscales of the Gaussian filtered image based on the grayscales of the Gaussian filtered image and the preset proportion comprises:
acquiring, based on the number of pixels and a grayscale of each pixel of the Gaussian filtered image, and the preset proportion, a first grayscale used for distinguishing a shadowy area and a highlighted area of the image; and
adjusting the grayscales of the Gaussian filtered image based on the grayscale of each pixel of the Gaussian filtered image and the first grayscale.

4. The method according to claim 3 , wherein the acquiring, based on the number of pixels and the grayscale of each pixel of the Gaussian filtered image, and the preset proportion, the first grayscale used for distinguishing the shadowy area and the highlighted area of the image comprises:
determining the number of pixels corresponding to each grayscale in an ascending order of grayscale, based on the grayscale of each pixel of the Gaussian filtered image;
determining a first value based on the number of the pixels of the Gaussian filtered image and the preset proportion; and
acquiring the first grayscale based on the first value and the determined number of the pixels corresponding to each grayscale.

5. The method according to claim 4 , wherein the acquiring the first grayscale based on the first value and the determined number of the pixels corresponding to each grayscale comprises:
accumulating the determined number of the pixels corresponding to each grayscale one by one in the ascending order of grayscale; and
determining one grayscale as the first grayscale, if an accumulation result obtained before adding the number of the pixels corresponding to the one grayscale is less than the first value and an accumulation result obtained after adding the number of the pixels corresponding to the one grayscale is greater than or equal to the first value.

6. The method according to claim 3 , wherein the adjusting the grayscales of the Gaussian filtered image based on the grayscale of each pixel of the Gaussian filtered image and the first grayscale comprises:
if a grayscale of a first pixel of the Gaussian filtered image is less than the first grayscale, adjusting the grayscale of the first pixel by applying

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performing no adjustment on a grayscale of a first pixel, if the grayscale of the first pixel of the Gaussian filtered image is equal to the first grayscale; or
if a grayscale of a first pixel of the Gaussian filtered image is greater than the first grayscale, adjusting the grayscale of the first pixel by applying

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Assignees

• Tencent Tech Shenzhen Co Ltd

Inventors

• Hu Shimin
• Wang Jianyu
• Li Baoli
• Deng Haifeng
• Li Xianying

Classifications

• G06T5/20 Primary

  using local operators · CPC title

• G06T5/40

  using histogram techniques · CPC title

• G06T5/002

  Physics · mapped topic

• G06T5/50

  using two or more images, e.g. averaging or subtraction · CPC title

• G06T5/009

  Physics · mapped topic