Self-adaptive low-light level image intensification method for reducing color cast

An image enhancement and low-light technology, applied in image enhancement, image analysis, image data processing, etc., can solve problems such as over-suppression or over-enhancement of bright areas, failure of image enhancement, and aggravation of image color cast.

Active Publication Date: 2017-06-23
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0010] The present invention aims to solve the problems of the existing low-illuminance image enhancement methods, such as the aggravation of the color shift of the image after enhancement, poor processing of the brighter areas of the image, resulting in over-suppression or over-enhancement of the brighter areas, and the existing method for different brightness images The problem of not being able to adaptively enhance the image

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  • Self-adaptive low-light level image intensification method for reducing color cast
  • Self-adaptive low-light level image intensification method for reducing color cast
  • Self-adaptive low-light level image intensification method for reducing color cast

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specific Embodiment approach 1

[0075] Specific implementation mode one: combine figure 1 To describe this embodiment,

[0076] An adaptive low-light image enhancement method for reducing color shift, comprising the following steps:

[0077] Step 1, input the low-illuminance image L, and convert it to the RGB color space, and obtain the RGB three-channel image of the low-illuminance image L;

[0078] Step 2, performing an inverse S-type transformation on the RGB three-channel image of the low-illuminance image L, weakening the color shift phenomenon of the low-illuminance image, and obtaining the inverse image I; figure 2 is the inverse S-shaped transformation curve adopted;

[0079] Step 3: Invert the inverse image I to obtain the inverse image H, calculate the minimum value of each pixel of the inverse image H in the three channels of RGB, obtain the initial dark channel image D, and process the initial dark channel image value filtering to obtain the median filtering image D median , using the median...

specific Embodiment approach 2

[0089] The formula of the inverse S-type transformation described in step 2 of the present embodiment is as follows:

[0090] I(i,j)=255*(a-ln(-1+260 / (L(i,j)+4))) / b

[0091] Among them, I(i,j) and L(i,j) are the pixel points in row i and column j of the inverse image I and low-illumination image L respectively; a and b are transformation parameters, and the value of a is 4. The value of the transformation parameter b is 8.

[0092] Other steps and parameters are the same as those in the first embodiment.

specific Embodiment approach 3

[0094] The specific process of step 3 of this embodiment includes the following steps:

[0095] Step 31, using the formula H(i,j)=255-I(i,j) to invert the inverse image I to obtain an inverse image H;

[0096] Wherein, I(i,j) is row i in reverse image I, pixel point j; L(i,j) is row i in reverse image H, pixel point j column;

[0097] Step 32, use the formula Obtain the initial dark channel image D;

[0098] Among them, D(i, j) is the i-th row and j-th column pixel in the initial dark channel image D; min represents the minimum value operation; c is R, G, B, corresponding to the three red, green and blue in the RGB color space color channel, h c (i, j) is the i-th row and the j-th column pixel point of a certain channel of the inverted image H in the RGB color space;

[0099] Step 33: Perform a median filter operation on the initial dark channel image to obtain a median filter image. The specific calculation formula is as follows:

[0100]

[0101] Among them, D medi...

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Abstract

The invention discloses a self-adaptive low-light level image intensification method for reducing color cast, relates to low-light level image intensification methods, and aims to solve the problems that the image color cast is intensified when a conventional low-light level image intensification method is used, and a relatively bright area of an image is over-inhibited or over-intensified when being not well processed. The self-adaptive low-light level image intensification method comprises the following steps: firstly, converting a low-light level image into a RGB (Red, Green, Blue) color space, performing inverted S-shaped conversion, performing inversion, calculating minimum values of different pixel points of reversed images at three RGB channels so as to obtain initial dark channel images, and performing median filtering so as to obtain atmosphere light intensity estimation values; converting the inversion images into an HSV color space, and calculating self-adaptive intensification parameters by taking average gray level values of a V channel as average brightness; calculating transmissivity images according to atmosphere imaging equations, modifying so as to obtain transmissivity smooth images, with the atmosphere imaging equations, performing demisting operation on the three RGB channels of the inversion images, performing inversion, and performing S-shaped conversion, thereby obtaining finally intensified images. The self-adaptive low-light level image intensification method is applicable to intensification processing on images.

Description

technical field [0001] The invention relates to the field of digital image processing, in particular to a low-illuminance image enhancement method. Background technique [0002] With the development of optical system manufacturing technology and optical detection technology, various optical imaging devices are increasingly used in civilian and military fields, such as civilian optical digital photography and camera systems, intelligent optical video surveillance systems and military Optical imaging guidance system and optical imaging reconnaissance system. However, when the detector sensitivity is relatively low and the ambient light conditions are insufficient, the images formed by these optical systems have various degradation problems, such as reduced image contrast, insufficient brightness, etc., resulting in the inability of human eyes or digital image processing systems to clearly and accurately distinguish Target and background, it is difficult to obtain the target i...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T5/00G06T7/90
CPCG06T2207/10024G06T5/92G06T5/73
Inventor 遆晓光张雨
Owner HARBIN INST OF TECH
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