A low-light image enhancement method and system

An image enhancement, low-illumination technology, applied in the field of image processing, can solve the problems of lack of universality, large amount of calculation, difficult to process high-definition images in real time, etc., and achieve the effect of avoiding image blur, small amount of calculation, and maintaining image edge information

Active Publication Date: 2017-04-26
深圳市百乐奇科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In view of this, the technical problem to be solved by the present invention is to provide a low-illuminance image enhancement method and system that is robust, easy to implement, and more suitable for human visual characteristics, so as to solve the problem that the current low-illuminance image enhancement method has a large amount of computation, Lack of universality, difficult to deal with technical problems of high-definition images in real time

Method used

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Embodiment 1

[0066] Such as figure 1 As shown, a low-illuminance image enhancement method provided by an embodiment of the present invention includes the following steps:

[0067] S10. Convert the input original image from RGB space to HIS space.

[0068] Preferably, the following formula can be used for conversion:

[0069]

[0070]

[0071]

[0072]

[0073] Among them, I represents the brightness, S represents the saturation, H represents the hue; R, G, and B represent the three color channels of red, green and blue respectively; min() represents the minimum value, mean() represents the mean value; the value range of A is [200,255]. The value of A is such that when a pixel is very dark, the S value of the pixel is close to 0, and when the color of a pixel is bright, the S value tends to 1. Therefore, the value range of A is [200,255] .

[0074] Specifically, the saturation S reflects the color purity, and its value ranges from 0 to 1. The greater the saturation, the brig...

Embodiment 2

[0097] Such as image 3 As shown, a kind of luminance adaptive filtering method that the preferred embodiment of the present invention provides, this method is based on template window operation, comprises the following steps:

[0098] S2011, preset M different N*N template windows.

[0099] Among them, M is an integer greater than 1, and N is an odd number including 3 or more; the value in the template window is composed of 0 and 1, and the polygons composed of points with a value of 1 are different in shape, and all polygons are combined to cover the entire template. window;

[0100] Specifically, M different N*N template windows are set in advance, the values ​​in the template window are composed of 0 and 1, M is an integer greater than 1, N is an odd number including 3 or more, and the M different N*N The shape of polygons composed of points with a value of 1 in the template window of N is different. The principle of polygon selection is that all polygons should cover th...

Embodiment 3

[0111] Such as Figure 5 As shown, a method for adjusting the contrast of an illumination map provided by a preferred embodiment of the present invention includes the following steps:

[0112] S2031. Eliminate pixels whose proportions of both ends of the illumination value in the illumination map are smaller than a preset proportion value.

[0113] Specifically, removing pixels whose light values ​​account for a small proportion can further eliminate the influence of noise, and the preset proportion value is generally 1% of the pixels.

[0114] S2032. Calculate the average illumination value of the remaining pixels.

[0115] S2033. Subtract the average illumination value from the illumination value of each pixel of the remaining pixels to obtain an illumination difference map.

[0116]S2034. Multiply the illumination difference of each pixel in the illumination difference map by a preset adjustment factor.

[0117] Wherein, the preset adjustment factor takes a value between...

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Abstract

The invention discloses a low-illumination image enhancement method and system, and belongs to the technical field of image processing. The method comprises the steps of converting an input original image into an HIS space from an RGB space, keeping the saturability and the hue component of the image unchanged, enhancing the brightness component, converting the image with the brightness enhanced into the RGB space from the HIS space and outputting the image. According to the low-illumination image enhancement method and system, the image brightness is improved, extremely-dark areas (the areas close to black) are prevented from being changed into bright-colored areas after being enhanced, and the image adapts to the human visual characteristics better. Meanwhile, the complexity is low, the calculation amount is small, high-definition images can be processed in real time, and the performance requirement for hardware can be lowered.

Description

technical field [0001] The invention relates to the technical field of image processing, in particular to a low-illuminance image enhancement method and system. Background technique [0002] In the application of image acquisition or video surveillance, there are often low-illumination situations such as night vision or backlight, and the collected images are dark and have low recognizability. Specific applications need to be processed after image enhancement. Image enhancement is to expand the brightness range of the image and improve the overall brightness of the image, improve the subjective quality of the image, so that the unrecognizable image details can be recognized by human eyes or machines. [0003] Common image enhancement processing methods include brightness transformation method, homomorphic filtering method, gradient domain enhancement method and Retinex enhancement method, etc. The brightness transformation method represented by the histogram equalization me...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06T5/00
Inventor 李芳吴金勇王军
Owner 深圳市百乐奇科技有限公司
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