Low-illumination image enhancement method based on local contrast stretching

A technology of local contrast and image enhancement, applied in image enhancement, image data processing, instruments, etc., can solve the problems of poor quality of enhanced images, inability to guarantee the details, texture and clarity of enhanced images, so as to enhance brightness contrast, improve The effect of image quality

Active Publication Date: 2020-12-04
HARBIN UNIV OF SCI & TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] The purpose of the present invention is to solve the problem that the image detail, texture and clarity of the enhanced image cannot be guaranteed by the existing method, resulting in the poor quality of the obtained enhanced image, and a low-illuminance image enhancement based on local contrast stretching is proposed method

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  • Low-illumination image enhancement method based on local contrast stretching
  • Low-illumination image enhancement method based on local contrast stretching
  • Low-illumination image enhancement method based on local contrast stretching

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specific Embodiment approach 1

[0019] Specific implementation mode one: combine figure 1 This embodiment will be described. A low-illuminance image enhancement method based on local contrast stretching described in this embodiment, the method is specifically implemented through the following steps:

[0020] Step 1, collect the original RGB image, convert the collected original RGB image into an HSV image, and obtain the V channel data, H channel data and S channel data of the HSV image;

[0021] Step 2, performing local contrast stretching on the local contrast of the V channel data of the HSV image to obtain the stretched local contrast;

[0022] Step 3, performing grayscale mapping on the V channel data of the HSV image to obtain an initial iteration value;

[0023] Step 4, use the stretched local contrast and iterative initial value to calculate the enhanced V channel data, convert the HSV image formed by the H channel data, the S channel data and the enhanced V channel data into an RGB image, and obta...

specific Embodiment approach 2

[0024] Specific implementation mode two: combination figure 2 This embodiment will be described. The difference between this embodiment and the specific embodiment one is: the specific process of the second step is:

[0025] The form of the local contrast stretching function is shown in formula (1):

[0026]

[0027] in: Represents the stretched local contrast of the V channel pixel (x, y), C x,y Indicates the local contrast of the pixel point (x, y) in the V channel data obtained in step 1; A(0.45), B(0.45), A(1) and B(1) are intermediate functions.

specific Embodiment approach 3

[0028] Specific embodiment three: the difference between this embodiment and specific embodiment two is: the expressions of the intermediate functions A (0.45), B (0.45), A (1) and B (1) are respectively:

[0029] A(0.45)=max[(C x,y +1) 0.45 ] (2)

[0030] B(0.45)=min[(C x,y +1) 0.45 ] (3)

[0031] A(1)=max(C x,y +1) (4)

[0032] B(1)=min(C x,y +1) (5)

[0033] Among them: max means to take the maximum value, and min means to take the minimum value.

[0034] In this embodiment, in the process of obtaining the maximum and minimum values, it is necessary to traverse the local contrast of each pixel in order to obtain (C x,y +1) 0.45 The maximum and minimum values ​​of (C x,y +1) maximum and minimum values.

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Abstract

The invention discloses a low-illumination image enhancement method based on local contrast stretching, and belongs to the technical field of image enhancement. According to the method, the problem that the quality of the obtained enhanced image is poor due to the fact that image details, textures and sharpness of the enhanced image cannot be guaranteed by adopting an existing method is solved. According to the invention, the method comprises the steps: stretching the local contrast of the image, so that the texture, details and definition characteristics of the output image are improved; secondly, designing a segmented global gray mapping method for calculating an initial value of an iterative process, thereby improving the global brightness contrast of the enhanced image. Experimental results prove that the image enhancement algorithm designed by the invention can effectively improve the image quality and enhance the brightness contrast of the image, and image details are very suitable for human eye observation. The method can be applied to enhancement of low-illumination images.

Description

technical field [0001] The invention belongs to the technical field of image enhancement, and in particular relates to a low-illuminance image enhancement method based on local contrast stretching. Background technique [0002] Due to the uneven illumination of the real environment, there are low-illumination areas in digital images with low brightness. The presence of low-illuminance areas leads to poor image visibility, and it is difficult to recognize details, textures, and image content in low-illuminance areas. Therefore, how to overcome the problem of image quality degradation caused by low-illumination areas has become a hot spot in academic research. Commonly used low-light image enhancement algorithms include: contrast enhancement algorithm based on histogram equalization; image enhancement algorithm based on global gray scale stretching; image enhancement algorithm based on wavelet transform, etc. Although these algorithms can improve the light-dark contrast of t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T5/00G06T5/40
CPCG06T5/007G06T5/40
Inventor 赵蓝飞孙瑞阳段炼孙玉滨
Owner HARBIN UNIV OF SCI & TECH
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