Rapid low-illumination image enhancing method based on improved dark channel prior

A dark channel prior and dark channel image technology, applied in the field of fast low-light image enhancement, can solve the problems of poor processing effect, poor real-time performance, and inapplicability of light-colored areas, so as to enhance brightness and contrast, and improve image and video quality Effect

Active Publication Date: 2013-10-09
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0009] The present invention aims to solve the problems of large amount of calculation, poor real-time performance, easy blurring of edge information, dark channel prior method is not applicable to light-colored areas, and the original low-illuminance enhancement method based on dark channel priori is not suitable for reflection and light. The problem of poor treatment effect in unevenly illuminated areas provides a fast low-light image enhancement method based on improved dark channel priors

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  • Rapid low-illumination image enhancing method based on improved dark channel prior
  • Rapid low-illumination image enhancing method based on improved dark channel prior
  • Rapid low-illumination image enhancing method based on improved dark channel prior

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specific Embodiment approach 1

[0030] Specific Embodiment 1: The fast low-light image enhancement method with improved dark channel prior in this embodiment includes the following steps:

[0031] Step 1: Input the image I(i,j), obtain the size of the image I(i,j) as w*h, and the RGB three-channel image IR(i,j), IG(i ,j), IB(i,j), where w is the width of the image, h is the height of the image, IR(i,j), IG(i,j), and IB(i,j) are the red and green colors of the image respectively blue three-channel image;

[0032] Step 2: For each pixel of the image I(i,j), find the minimum value in the grayscale of the RGB three-channel images IR(i,j), IG(i,j), and IB(i,j), Recorded as Imin(i, j), the calculation formula is as follows:

[0033] I min ( i , j ) = min c ∈ { R , G ...

specific Embodiment approach 2

[0089] Specific embodiment two: the difference between this embodiment and the specific embodiment is: the method for judging the light-colored area in the image in step four is:

[0090] A. The absolute value of the difference between the gray levels of the three RGB channels is less than 5;

[0091] B. The dark channel gray value corresponding to the pixel is greater than the average dark channel gray value meanray;

[0092] C. The dark channel gray value corresponding to the pixel is less than half maxgray / 2 of the maximum dark channel gray value. Other steps and parameters are the same as those in Embodiment 1.

specific Embodiment approach 3

[0093] Specific implementation mode three: the difference between this implementation mode and specific implementation mode one or two is that: the steps of performing linear smoothing on the modified dark channel image in step five are as follows:

[0094] a, determine the size of the window used to smooth the dark channel image according to the size of the image I (i, j);

[0095] b. Calculate the parameter a of the linear approximation for each window k and b k ;

[0096] c. Approximate parameter a for all windows containing each pixel k and b k Perform an average to obtain the approximate parameters after the average;

[0097] d. Carry out linear approximation to the image with the approximation parameters after the average;

[0098] Among them, the formula for linearly smoothing the modified dark channel image is: For a window W with a size of M*M centered on point k k All pixels within x:E x =a k D. x +b k , M=N-2, N is the size of the window used when obtainin...

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Abstract

The invention discloses a rapid low-illumination image enhancing method based on improved dark channel prior, which relates to a rapid low-illumination image enhancing method, and is used for solving the problems of a conventional low-illumination image enhancing method that the calculation amount is large, that the real-time performance is poor, that boundary information is easy to be fuzzed, that a dark channel prior method is not applicable to light color areas, and that an original low illumination enhancing method based on dark channel prior has a poor processing effect on light reflecting and non-uniform illumination areas. The method comprises the following steps of: firstly, inputting an image I (i, j); secondly, calculating an initial dark channel image D (i, j) of the image I (i, j); thirdly, calculating an average pixel dark channel gray value and a maximum dark channel gray value of the D (i, j); fourthly, judging the light color area of the image I (i, j); fifthly, carrying out linear smoothing on the modified dark channel image; sixthly, acquiring a histogram of the smoothed illumination intensity image, and confirming standard illumination intensity; and seventhly, recovering the image. The method belongs to the field of image and video processing.

Description

technical field [0001] The invention relates to a fast low-illuminance image enhancement method, which belongs to the field of image and video processing. Background technique [0002] Under cloudy and rainy days and low light conditions at night, the overall gray value and image contrast of the obtained image are reduced due to the poor lighting conditions of the surrounding environment when collecting images and videos and the low illuminance, which leads to the aggravation of the noise of the image or video equipment. Image quality and visibility are severely degraded, making it difficult to identify regions of interest. In addition, some areas in the target image are difficult to extract the information of this part of the image due to the lack of illumination or the fusion of the shadow area and the background. Therefore, to enhance the image brightness and contrast under low illumination and improve the overall image quality, it can be used in civilian intelligent vid...

Claims

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Application Information

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IPC IPC(8): G06T5/00G06T5/40
Inventor 遆晓光曲悠杨张彬彬
Owner HARBIN INST OF TECH
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