CN109493289A - One kind having brightness and saturation degree Double Nonlinear image enchancing method - Google Patents
One kind having brightness and saturation degree Double Nonlinear image enchancing method Download PDFInfo
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Abstract
The invention discloses one kind have brightness and saturation degree Double Nonlinear image enchancing method, first by the color image of input from RGB (Red Green Blue) color space conversion be HSV (Hue Saturation Value) color space；The channel V can be enhanced by being multiplied by V channel image using the enhancing coefficient obtained by the non-linear concave function of monotone decreasing；Channel S image is multiplied by one, non-linear enhancing is carried out by the enhancing coefficient that nearly Gaussian function linear change obtains；Image is finally converted back into RGB color from hsv color space, obtains brightness and the dual enhancing image of saturation degree.The non-linear Enhancement Method of color image provided by the invention, can enhance the overall brightness and saturation degree of image, to improve the total quality of image, be suitable for all kinds of color images, and computation complexity is low, obvious processing effect.
Description
Technical field
The invention belongs to image, the brightness of video and saturation degrees to enhance field, in particular to a kind of to have brightness and saturation
Spend Double Nonlinear image enchancing method.
Background technique
It is influenced in actual life by the variability of environmental factor and appointed condition, the image and video of normal photographing are in
The effect revealed often is not enough to reach the vision requirement of human eye.Therefore, video image enhancement technology is come into being.People pass through
Image enhancement technique carries out enhancing processing to required image and video, to get a desired effect.
Image enhancement technique can be divided into two classes according to the difference of spatial domain and be based on airspace enhancement algorithm and based on frequency domain
Enhancing algorithm.It is the enhancing algorithm based on airspace with brightness and saturation degree Double Nonlinear image enchancing method.Same base
Enhancing algorithm in airspace has gamma transformation etc., and gamma transformation is can be to dark picture areas pixel and bright according to the difference of gamma value
Area's pixel is stretched and is compressed respectively.Although it is thin that gamma transformation can show the more dark spaces of image in conversion process
Section, but at the same time also can lost part clear zone information.Although proposing many innovatory algorithms in view of this later, do not have
Have and fundamentally solve these problems, is only improved in terms of the intensity of its brightness enhancing.Compared with existing gamma transformation,
The present invention overcomes the inherent shortcomings of gamma transformation.
It is adaptive by being realized to parameter setting with brightness and saturation degree Double Nonlinear image enchancing method, enhancing
While brightness of image and saturation degree, also also there is a degree of enhancing to the details of image.The method is to picture and video
Enhancing during, not will cause that enhancing is insufficient or enhancing over-education phenomenon, the defect of loss in detail compensated for, to meet human eye
The requirement of visual characteristic.
Summary of the invention
It is an object of the invention to overcome the deficiencies of the prior art and provide one kind to have brightness and saturation degree Double Nonlinear
Image enchancing method, brightness and saturation degree to image are adaptively enhanced, and at the same time can will be unconspicuous thin in image
Section is enhanced, and solves the enhancing deficiency in existing gamma transformation correlation technique or details is lost excessively after enhancing and enhancing
The problem of mistake, can obtain the image with good visual characteristic by the method for the invention.
The technical solution adopted by the present invention to solve the technical problems is:
One kind having brightness and saturation degree Double Nonlinear image enchancing method, comprising the following steps:
Step a) receives the color image of the RGB color of 8 bits of input, and the color image is converted
To hsv color space；The image in the channel V is denoted as img_v, and the channel V is ranked up from small to large by pixel value, before calculating
The average gray darkmean of 50% pixel, is then calculated parameter value vk by e index function；
Step b), each pixel for acquiring V channel image using the non-linear concave function of vk and monotone decreasing are corresponding
Enhancing coefficient noline_V；The image in the channel V, which is multiplied by enhancing coefficient noline_V, can be obtained the enhanced figure in the channel V
Picture；
The image of channel S is denoted as img_s, and seeks the average value of its gray value of image by step c), is denoted as meanS；Benefit
The enhancing coefficient gauss of its channel S is sought with nearly Gaussian curve；Wherein the mean value of Gaussian curve is defaulted as 128, Gaussian curve
Variance is auto-adaptive parameter；
Step d) obtains the enhancing coefficient noline_S of channel S by carrying out Serial regulation to enhancing coefficient gauss；By S
The image in channel is multiplied by enhancing coefficient noline_S and obtains the enhanced image of channel S；By enhanced hsv color spatial image
RGB color image is converted back, final brightness and saturation degree Double Nonlinear enhancing image is obtained.
Preferably, in step a), the e index function representation is as follows:
Vk=exp (darkmean/64-1) * 90+70.
Preferably, in step b), each picture of V channel image is acquired using the non-linear concave function of vk and monotone decreasing
Vegetarian refreshments corresponding enhancing coefficient noline_V, specific as follows:
Noline_V=((255+vk)/(img_v+vk) -1)k+1
Wherein, the value range of k is 1.5~2.5.
Preferably, in step c), the nearly Gaussian curve is expressed as follows:
Gauss=exp (- (img_s- μ)2/(2*σ2))
Wherein, μ indicates mean value, and σ indicates that variance, the acquisition modes of variance are as follows:
σ=tan ((meanS-128)/128*0.45 π)+50
Wherein, π indicates pi.
Preferably, in step d), the enhancing coefficient noline_S is expressed as follows:
Noline_S=1+ ((250-meanS)/500) * gauss.
Preferably, in step a), the color image is transformed into after hsv color space, further includes: by channel S and V
The pixel value range in channel is amplified to 0-255 from 0-1.
Preferably, in step d), it is described by enhanced hsv color spatial image convert back RGB color image it
Before, further includes: by channel S and the pixel value range in the channel V from 0-255 boil down to 0-1
The present invention has the advantage that compared with existing the relevant technologies
It is of the invention a kind of that there is brightness and saturation degree Double Nonlinear image enchancing method, brightness to input picture and full
Adaptively enhanced with degree, and at the same time details unconspicuous in image can be enhanced.By the method for the invention, can
The brightness and saturation degree of appropriate enhancing input picture, and the detail section of image can be enhanced, so that image is met the vision of human eye
Characteristic.
Invention is further described in detail with reference to the accompanying drawings and embodiments；But one kind of the invention have brightness and
Saturation degree Double Nonlinear image enchancing method is not limited to the embodiment.
Detailed description of the invention
Fig. 1 is the flow chart with brightness and saturation degree Double Nonlinear image enchancing method of the invention；
Fig. 2 is the experimental result picture of the embodiment of the present invention；Wherein Fig. 2 (a) is original image, and Fig. 2 (b) is after luminance channel enhances
Effect picture, Fig. 2 (c) be brightness and the dual enhanced effect picture of saturation degree.
Specific embodiment
Referring to described in Fig. 1, there is brightness and saturation degree Double Nonlinear image enchancing method for the present invention is a kind of, specifically wrap
Containing following steps:
Step a) receives the color image of the RGB color of 8 bits of input, and the color image is converted
To hsv color space；The image in the channel V is denoted as img_v, and the channel V is ranked up from small to large by pixel value, before calculating
The average gray darkmean of 50% pixel, is then calculated parameter value vk by e index function.
The step a) is specifically included:
Step a1) input 8 bits RGB color digital color image, utilize international color space
The color image of the RGB color of input is converted into the color image in hsv color space by conversion formula；And by channel S and
The pixel value range in the channel V is amplified to 0-255 from 0-1, convenient for unifiedly calculating below；
Step a2) V channel image is denoted as img_v, and seek accounting for being averaged for 50% pixel before total pixel number in the channel V
Value, concrete operations are as follows: the histogram of statistics V channel image is denoted as array hist；Find out on histogram the total picture of Zhan since the left side
Preceding 50% grey scale pixel value of prime number, is denoted as gray1；Seek in histogram gray value from 0 into gray1 all pixels gray scale
The average value of value, is denoted as darkmean；
Step a3) utilize dark space mean value darkmean and e index function: the vk=exp (darkmean/ of V channel image
64-1) * 90+70 can be in the hope of relevant parameter vk, and the brightness for controlling image enhances；
Step b) is corresponding using each pixel that the non-linear concave function of vk and monotone decreasing acquire V channel image
Enhance coefficient noline_V；The image in the channel V, which is multiplied by enhancing coefficient noline_V, can be obtained the enhanced image in the channel V.
Specifically, being based on the vk, each pixel of V channel image is passed through to the non-linear concave function of monotone decreasing:
Noline_V=((255+vk)/(img_v+vk) -1) k+1 is calculated, and wherein the value range of k is 1.5~2.5, default value
It is 1.75, obtains the corresponding enhancing coefficient noline_V of each pixel of V channel image；By each pixel of V channel image
The enhanced image in the channel V can be obtained in enhancing multiplication corresponding thereto；V channel image is carried out using the method
Nonlinear extension can be such that the brightness of dark space part is adaptively enhanced, and clear zone part luma almost remains unchanged, and keeps away
Exempt from image overexposure.
The image of channel S is denoted as img_s by step c), and seeks the average value of its gray value of image, is denoted as meanS；Benefit
The enhancing coefficient gauss of its channel S is sought with nearly Gaussian curve.
Specifically, the nearly Gaussian function is expressed as follows:
Gauss=exp (- (img_s- μ) 2/ (2* σ 2))
The mean μ of nearly Gaussian function is the intermediate value 128 of gray value, variance be calculated using meanS as parameter it is adaptive
It should value σ=tan ((meanS-128)/128*0.45 π)+50.The purpose of this step is: becoming its variance yields slowly at 50
Change, saturation degree enhancing range can be made to carry out appropriate adjustment.
Step d) obtains the enhancing coefficient noline_S of channel S by carrying out Serial regulation to enhancing coefficient gauss；By S
The image in channel is multiplied by enhancing coefficient noline_S and obtains the enhanced image of channel S；By enhanced hsv color spatial image
RGB color image is converted back, final brightness and saturation degree Double Nonlinear enhancing image is obtained.
Specifically, enhancing coefficient noline_S=1+ ((250-meanS)/500) the * gauss, by channel S image
The enhancing multiplication of each pixel corresponding thereto, can be obtained the enhanced image of channel S；And by channel S and the channel V
Pixel value range from 0-255 boil down to 0-1, so as to the conversion of subsequent color space；Then by enhanced hsv color space
Color image converts back the color image of RGB color using international color space conversion formula, can be obtained final bright
Degree and saturation degree Double Nonlinear enhance image.
It is shown in Figure 2, it is the reinforcing effect comparison diagram of the present embodiment experimental image, wherein Fig. 2 (a) is original image, Fig. 2
It (b) is the enhanced effect picture of luminance channel, Fig. 2 (c) is brightness and the dual enhanced effect picture of saturation degree.Enhance from experiment
Effect picture afterwards, which can be seen that the method for the present invention, can carry out enhancing appropriate to its brightness and saturation degree for color image,
Processing result is naturally, meet the visual characteristic of human eye.
The above is only a preferable embodiments in present example.But the present invention is not limited to above-mentioned embodiment party
Case, it is all by the present invention any equivalent change and modification done, generated function without departing from this programme range when,
It belongs to the scope of protection of the present invention.
Claims (7)
1. one kind has brightness and saturation degree Double Nonlinear image enchancing method, which comprises the following steps:
Step a) receives the color image of the RGB color of 8 bits of input, and the color image is transformed into HSV
Color space；The image in the channel V is denoted as img_v, and the channel V is ranked up from small to large by pixel value, calculates preceding 50%
The average gray darkmean of pixel, is then calculated parameter value vk by e index function；
Step b) acquires the corresponding increasing of each pixel of V channel image using the non-linear concave function of vk and monotone decreasing
Strong coefficient noline_V；The image in the channel V, which is multiplied by enhancing coefficient noline_V, can be obtained the enhanced image in the channel V；
The image of channel S is denoted as img_s, and seeks the average value of its gray value of image by step c), is denoted as meanS；Using close
Gaussian curve seeks the enhancing coefficient gauss of its channel S；Wherein the mean value of Gaussian curve is defaulted as 128, the variance of Gaussian curve
For auto-adaptive parameter；
Step d) obtains the enhancing coefficient noline_S of channel S by carrying out Serial regulation to enhancing coefficient gauss；By channel S
Image be multiplied by enhancing coefficient noline_S obtain the enhanced image of channel S；Enhanced hsv color spatial image is converted
RGB color image is returned, final brightness and saturation degree Double Nonlinear enhancing image is obtained.
2. according to claim 1 a kind of with brightness and saturation degree Double Nonlinear image enchancing method, feature
It is, in step a), the e index function representation is as follows:
Vk=exp (darkmean/64-1) * 90+70.
3. according to claim 1 a kind of with brightness and saturation degree Double Nonlinear image enchancing method, feature
It is, in step b), each pixel for acquiring V channel image using the non-linear concave function of vk and monotone decreasing is corresponding
Enhance coefficient noline_V, specific as follows:
Noline_V=((255+vk)/(img_v+vk) -1)k+1
Wherein, the value range of k is 1.5~2.5.
4. according to claim 1 a kind of with brightness and saturation degree Double Nonlinear image enchancing method, feature
It is, in step c), the nearly Gaussian curve is expressed as follows:
Gauss=exp (- (img_s- μ)2/(2*σ2))
Wherein, μ indicates mean value, and σ indicates that variance, the acquisition modes of variance are as follows:
σ=tan ((meanS-128)/128*0.45 π)+50
Wherein, π indicates pi.
5. according to claim 1 a kind of with brightness and saturation degree Double Nonlinear image enchancing method, feature
It is, in step d), the enhancing coefficient noline_S is expressed as follows:
Noline_S=1+ ((250-meanS)/500) * gauss.
6. according to claim 1 a kind of with brightness and saturation degree Double Nonlinear image enchancing method, feature
It is, in step a), the color image is transformed into after hsv color space, further includes: by the pixel of channel S and the channel V
Value range is amplified to 0-255 from 0-1.
7. according to claim 6 a kind of with brightness and saturation degree Double Nonlinear image enchancing method, feature
Be, in step d), it is described enhanced hsv color spatial image is converted back into RGB color image before, further includes:
By channel S and the pixel value range in the channel V from 0-255 boil down to 0-1.
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| CN114120932B (en) * | 2021-11-30 | 2022-11-22 | 中航华东光电有限公司 | Liquid crystal display dimming method combined with image saturation adjustment |
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