Low-illumination color image enhancement method based on local extreme value

A local extremum and color image technology, applied in image enhancement, image analysis, image data processing, etc., can solve the problems of inaccurate illuminance image estimation, loss of details in high-brightness areas of enhanced images, and insufficient contrast enhancement in low-brightness areas. Achieve the effect of improving the enhancement effect, changing the histogram distribution, brightness and contrast enhancement

Active Publication Date: 2019-09-06
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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  • Application Information

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Problems solved by technology

[0005] The purpose of the present invention is: the present invention provides a low-illuminance color image enhancement method based on local extremum, which solves the problem of inaccurate illuminance image estimation in the existing method, which leads to the loss of details in the high-brightness area of ​​the enhanced image and insufficient contrast enhancement in the low-brightness area. The problem

Method used

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  • Low-illumination color image enhancement method based on local extreme value
  • Low-illumination color image enhancement method based on local extreme value
  • Low-illumination color image enhancement method based on local extreme value

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Embodiment 1

[0054] The existing method has the problem of inaccurate estimation of the contrast illuminance image, resulting in the loss of details in the high-brightness area of ​​the enhanced image, and insufficient contrast enhancement in the low-brightness area; therefore, this application proposes a low-illuminance color image enhancement method to overcome the above problems, the details are as follows:

[0055] A low-illuminance color image enhancement method based on local extremum, comprising the following steps:

[0056] Step 1: convert the original color image from RGB space to YUV space, and extract the intensity channel Y of YUV space as grayscale image I;

[0057] Step 2: Use the local extremum filter whose kernel gradually increases to iteratively filter the grayscale image I, and use the filtering result as the illuminance component L of the image;

[0058] Step 3: Separate the reflection component R from the grayscale image I according to the illuminance component L;

[...

Embodiment 2

[0062] Based on Embodiment 1, consider how to perform illuminance processing, image conversion, and how to optimize image details in this method. The details are as follows:

[0063] Such as Figure 2-6 As shown, step 1 includes the following steps:

[0064] Step 1.1: Get the original color image S ∈ R m×n , m×n represents the length and width of the original color image S;

[0065] Step 1.2: Convert the original color image from RGB space to YUV space, and extract the intensity channel Y as grayscale image I.

[0066] Step 2 includes the following steps:

[0067] Step 2.1: Construct a local extremum filter with a kernel of 3;

[0068] Step 2.2: Use the local extremum filter grayscale image I to filter to obtain all maximum and minimum points that meet the conditions;

[0069] The details of obtaining all the maximum and minimum points satisfying the conditions in step 2.2 are as follows:

[0070] 1) In the k*k neighborhood centered on pixel p, if at most k-1 elements ar...

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Abstract

The invention discloses a low-illumination color image enhancement method based on a local extreme value, and relates to the field of color image enhancement methods. The method comprises the steps ofstep 1, converting an original color image from an RGB space to a YUV space, and extracting an intensity channel Y of the YUV space as a grayscale image I; step 2, performing iterative filtering on the grayscale image I by using a local extreme value filter with gradually increased cores, and taking a filtering result as an illumination component L of the image; step 3, separating a reflection component R from the grayscale image I according to the illumination component L; step 4, carrying out gamma transformation on the contrast component L, and reconstructing the contrast component L and the reflection component R to obtain an enhanced image. The grayscale image is iteratively filtered by using the local extreme value filter with gradually increased cores, so that the problems of high-brightness region detail loss and low-brightness region contrast enhancement of the enhanced image caused by the existing method are solved, and the color fidelity of the enhanced image, the definition of dark region details and the detail information richness are improved.

Description

technical field [0001] The invention relates to the field of color image enhancement methods, in particular to a low-illuminance color image enhancement method based on local extreme values. Background technique [0002] With the rapid development of computer vision and digital image processing technology, imaging systems and monitoring equipment need to capture a large amount of image information every day. However, under uneven lighting conditions such as indoors and at night, the quality of the captured image will seriously deteriorate, specifically in the following two aspects: first, the image presents a large number of dark areas, the content of which is blurred, and a large number of details are lost; second, Under artificial light sources, some bright areas will appear in the image, making the overall brightness of the image uneven and the quality seriously degraded. Image enhancement technology is to process images according to specific needs, highlight certain inf...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T5/00G06T5/10
CPCG06T5/007G06T5/10G06T2207/10024Y02T10/40
Inventor 于璐阳蒲恬王崇宇宋立彭真明李美惠何艳敏赵学功杨春平龙鸿峰张天放
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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