CN102082897A - Method and device for color noise suppression - Google Patents
Method and device for color noise suppression Download PDFInfo
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- CN102082897A CN102082897A CN2011100441369A CN201110044136A CN102082897A CN 102082897 A CN102082897 A CN 102082897A CN 2011100441369 A CN2011100441369 A CN 2011100441369A CN 201110044136 A CN201110044136 A CN 201110044136A CN 102082897 A CN102082897 A CN 102082897A
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Abstract
The invention relates to a method and device for color noise suppression, and the method comprises the following steps: acquiring the brightness value of a pixel; and adjusting the chromaticity of the pixel according to the brightness value of the pixel, wherein when the brightness value is lower, the pixel needs to be adjusted to have lower color saturation, and when the brightness value is higher, the pixel needs to be adjusted to have higher color saturation. In the method, the color saturation is adjusted through the brightness situation of each digital image pixel, thereby effectively reducing the strength of the chromaticity of the pixels with the lower brightness, and further improving the situation that the higher color saturation or color noise of a digital image can generate adverse effects on the image quality when the brightness of the pixels is lower.
Description
The application is at dividing an application that female case application (application number: 200410080507.9, the applying date: on September 30th, 2004, denomination of invention: a kind of method of color noise suppressed and device) is proposed.
Technical field
The present invention relates to a kind of method and device that is suppressed at color noise under the low-light level, particularly relate to a kind of method and device of adjusting the color noise suppressed of pixel chroma according to pixel intensity with weighting.
Background technology
Along with the arriving of digital Age, digital camera replaces the use of traditional camera gradually, and the circulation of image information also replaces with digitized video gradually from traditional photo.Therefore, the good and the bad of digitized video quality also more and more is subjected to requirement.
At present, digitized video is unit with the pixel, and the color of each pixel is by being made of three primary colors (R, G, B), and each pixel color all has its brightness and chroma.The good and the bad of digitized video quality then is to depend primarily on its brightness that presents picture, contrast and saturation.
As for existing processing to digitized video, be that first R, G, B value with each pixel of digitized video is converted to brightness (Y) signal and chroma (U, V) behind the signal, directly adjust luminance signal, chroma signals again, with respectively as to the adjustment of each pixel of digitized video on brightness, chroma, to improve brightness, contrast and the chroma of digitized video.Usually, if, some problems can occur directly to the luminance signal of each pixel representative of digitized video, when chroma signals adjusts.
Traditionally, and brightness (Y) signal and chroma (U, V) or (Cb, Cr) signal separate processes all can not considered together.Therefore, we adjust its color saturation at the give chapter and verse brightness of each image pixel.General TV is in video signal and image processing, if processing is bad, can the color noise occur at dark picture.
In view of this, the present invention proposes a kind of method and device of color noise suppressed, can effectively suppress the color noise on this digitized video when digitized video brightness is low.
Summary of the invention
Technical problem to be solved by this invention is to provide a kind of method and device of color noise suppressed, its brightness according to each image pixel (Y) signal is adjusted its color saturation, the color noise that suppresses low-light level to give its lower color saturation under the lower situation of brightness is when brightness is higher and make picture that more rich color be arranged for its higher color saturation.
For achieving the above object, the present invention proposes a kind of method of color noise suppressed, comprises the steps: to obtain the brightness value of a pixel; And adjust the chroma of described pixel according to the brightness value of described pixel, wherein, when described brightness value is low, makes described pixel have lower color saturation, and when described brightness value is higher, make described pixel have higher color saturation; And, in the step of the chroma of adjusting described pixel according to the brightness value of described pixel, be to adjust the pairing chroma of described pixel with weighting scheme, described weighting scheme comprises the steps: to provide a weighting function, wherein said weighting function and described weighting function relevant with a critical luminance with the brightness of described pixel as variable; Determine described critical luminance; Find out the pairing weighted value of described pixel intensity by described weighting function; And the chroma of adjusting corresponding described pixel according to described weighted value; And, described weighting function is one to have the linear function of boundary condition, if described weighting function is represented with W, described critical luminance is represented with Yth, the brightness of described pixel is represented with Yin, the slope of described linear function represents that with S described weighted value represents that with A then described weighting function can be expressed as: W (Yin)=S * (Yin-Yth)=A; And, if described weighted value does not exceed a weighting limits value, then adjust the chroma of described pixel according to described weighted value, if described weighted value exceeds described weighting limits value, then adjust the chroma of described pixel according to described weighting limits value.
And for achieving the above object, the present invention proposes a kind of device of color noise suppressed, comprising: a weighting determination device receives a luminance input signal and a critical luminance to export a weighted signal; One weighting restraint device, receive a described weighted signal and a weighting restricting signal, described weighting restricting signal determines a weighting limits value, and, described weighting restraint device is subjected under the situation of described weighting restricting signal control, limit the accurate position output of described weighted signal, with the weighted signal of output smaller or equal to described weighting limits value; And a weighting device, receive described weighting restraint device and export described weighted signal and at least one chroma input signal to export a chroma output signal; Wherein, when the brightness value of described luminance input signal hangs down, described weighted signal will make described chroma output signal have lower color saturation, and when the brightness value of described luminance input signal is higher, described weighted signal will make described chroma output signal have higher color saturation; And described weighting restraint device is a clamper; Described weighting determination device further comprises: a subtracter receives a described luminance input signal and a critical luminance signal to subtract each other output; And a multiplier, receive the output of described subtracter and a slope signal with the described weighted signal of output that multiplies each other; Described weighting device is a multiplier; The weighting function that is adopted is one to have the linear function of boundary condition, if described weighting function is represented with W, described critical luminance is represented with Yth, the brightness of described pixel is represented with Yin, the slope of described linear function is represented with S, described weighted value represents that with A then described weighting function can be expressed as: W (Yin)=S * (Yin-Yth)=A.
Preferably, described chroma input signal comprises one first chroma input signal and one second chroma input signal.
Preferably, described weighting device further comprises: one first multiplier receives described first chroma input signal and described weighted signal to export one first chroma output signal; And one second multiplier, receive described second chroma input signal and described weighted signal to export one second chroma output signal.
In preferred embodiment of the present invention, comprise more with clamper that as the weighting restraint device it is by receiving the accurate position of weighted signal that a weighting restricting signal is exported by the weighting determination device with the clamp restriction, with the accurate position of the restriction weighted signal that weighting device was received.
Describe the present invention below in conjunction with the drawings and specific embodiments, but not as a limitation of the invention.
Description of drawings
Fig. 1 is the flow chart of weighting in the color noise suppressing method of preferred embodiment of the present invention;
Fig. 2 is the coordinate schematic diagram of the weighting function work of preferred embodiment of the present invention;
Fig. 3 is the color Noise Suppression Device of preferred embodiment of the present invention;
Fig. 4 is the comparison diagram of digitized video picture before and after color Noise Suppression Device of the present invention.
Wherein, Reference numeral is as follows:
300-color Noise Suppression Device
305-weighting determination device
The 307-weighting device
The 310-subtracter
320,340,350-multiplier
321,325-weighted signal
The 330-clamper
360-critical luminance signal
The 365-slope signal
366-weighting restricting signal
The 370-luminance input signal
371,373-chroma input signal
381,383-chroma output signal
Embodiment
For further understanding and understanding being arranged to feature of the present invention, purpose and function, existing conjunction with figs. is described in detail as follows:
Because the present invention mainly is according to the brightness of pixel on digitized video performance, adjusts the pairing chroma of pixel by weighting, when brightness is low, gives its lower color saturation and suppress the color noise of low-light level.And weighting scheme please refer to Fig. 1, and Fig. 1 is the flow chart of weighting in the color noise suppressing method of preferred embodiment of the present invention.At first, provide a weighting function, this weighting function is relevant with a critical luminance, and with the brightness of pixel as variable, this is a step 101.Wherein, weighting function can be the straight line equation of linearity.
Then, determine critical luminance on the coordinate at weighting function place, on behalf of this weighting function, this critical luminance have the starting point of output valve, and this is a step 102.
Therefore, by weighting function, can find out the weighted value of respective pixel brightness, with as the weighting to the pixel chroma, this is a step 103.If critical luminance represents that with Yth the brightness of pixel represents that with Yin the weighting function of straight line equation is with W (Yin) expression, weighted value represents that with A then weighting function can be expressed as:
W(Yin)＝S×(Yin-Yth)＝A?if?Yin＞Yth
W(Yin)＝0 if?Yin＜＝Yth
Wherein, S is equational slope.
After obtaining weighted value by weighting function, might exceed its spendable boundary, boundary that must the restriction weighted value for fear of result according to this weighted value gain pixel chroma.Also therefore, after step 103 obtains weighted value, must judge whether weighted value exceeds a weighting limits value (Wmax), this step 104 if weighted value does not surpass this weighting limits value, is then adjusted the chroma of pixel according to this weighted value, and this is a step 105; Otherwise, if weighted value surpasses this weighting limits value, then adjust the chroma of pixel according to this weighting limits value, this is a step 106.
Please refer to Fig. 2, Fig. 2 is the coordinate schematic diagram of the weighting function work of preferred embodiment of the present invention.In Fig. 2, the pixel intensity Yin of input must be more than or equal to critical luminance (Yth), and it just has corresponding weighted value A by weighting function W (Yin).And the weighted value A that obtains by weighting function W (Yin) correspondence as the pixel intensity Yin of input is during above weighting limits value (Wmax), and then pixel intensity Yin exports with weighting limits value Wmax by the weighted value A that weighting function W (Yin) correspondence obtains.
Therefore, as shown in Figure 2, weighting function W (Yin) has corresponding weighted value A after pixel intensity Yin is more than or equal to critical luminance, and when pixel intensity Yin saw through the resulting weighted value A of weighting function W (Yin) greater than weighting limits value Wmax, weighted value then was restricted to weighting limits value Wmax.
Please refer to Fig. 3, Fig. 3 is the color Noise Suppression Device of preferred embodiment of the present invention.This color Noise Suppression Device 300 mainly is to operate according to the straight line equation that Fig. 2 step 103 is proposed.This color Noise Suppression Device 300 includes weighting determination device 305, as the clamper 330 and the weighting device 307 of weighting restriction, wherein weighting determination device 305 is made up of subtracter 310 and multiplier 320, and weighting device 307 is made up of 340,350 of multipliers.
The employed critical luminance of straight line equation, slope are then decided by the critical luminance signal 360 (Yth) of 310 receptions of subtracter in the weighting determination device 305 and the slope signal 365 (S) of multiplier 320 receptions respectively.The employed weighting limits value of straight line equation is then decided by the weighting restricting signal 366 that clamper 330 receives.
Therefore, when color Noise Suppression Device 300 receives the luminance input signal 370 of representing the digitized video pixel, chroma input signal 371 (U (in)), chroma input signal 373 (V (in)), subtract each other output after can receiving brightness input 370 (Yin), critical luminance signal 360 simultaneously via subtracter 310, multiplier 320 receives the output of multiplying each other behind the output of subtracter 310 and the slope signal 365 simultaneously, to obtain representing the weighted signal 321 of luminance input signal 370 gained weighted value after Fig. 2 straight line equation.And weighted signal 321 can be subjected under the situation of weighting restricting signal 366 controls at clamper 330, and clamp output is smaller or equal to the weighted signal 325 of weighting limits value (Wmax) level (level).At last, receive weighted signal 325 and chroma input signal 371 simultaneously at multiplier 340, and receive simultaneously at multiplier 350 under the situation of weighted signal 325 and chroma input signal 373, obtain chroma output signal 381,383 after can being multiplied by weighted signal 325 respectively by chroma input signal 371,373.
And the luminance input signal 370 of digital signal pixel is behind color Noise Suppression Device 300, it is according to the chroma input signal 371,373 of luminance input signal 370 adjustment digitized video pixels, with chroma output 381 (Uout), chroma output signal 383 (Vout).Digitized video then can be adjusted the chroma of digitized video pixel by above-mentioned mechanism according to the brightness of digitized video pixel.
Please refer to Fig. 4, Fig. 4 is the comparison diagram of digitized video picture before and after color Noise Suppression Device of the present invention.The left side is the original image without color Noise Suppression Device of the present invention, and right-hand part is the picture behind the inhibition noise of color Noise Suppression Device of the present invention.Significantly,,, adjust the pairing chroma of pixel, effectively suppressed the color noise of low-light level with weighting according to the brightness performance of pixel on the digitized video by the present invention.Comprehensively above-mentioned, the present invention proposes a kind of method and device of color noise suppressed, and by the brightness according to the digitized video pixel, the pairing chroma of pixel is adjusted in weighting.Therefore, the present invention more lowly gives its lower color saturation and suppresses the color noise of low-light level in brightness, when brightness is higher and make picture that more rich color be arranged for its higher color saturation.
Certainly, the present invention also can have other various embodiments, and for example obtaining also of above-mentioned weighted value can directly be obtained by lookup table mode or other similar image mode.Under the situation that does not deviate from spirit of the present invention and essence thereof, those of ordinary skill in the art work as can make various corresponding changes and distortion according to the present invention, but these corresponding changes and distortion all should belong to the protection range of the appended claim of the present invention.
Claims (4)
1. the method for a color noise suppressed is characterized in that, comprises the steps:
Obtain the brightness value of a pixel; And
Adjust the chroma of described pixel according to the brightness value of described pixel, wherein, when described brightness value is low, makes described pixel have lower color saturation, and when described brightness value is higher, make described pixel have higher color saturation;
And, in the step of the chroma of adjusting described pixel according to the brightness value of described pixel, be to adjust the pairing chroma of described pixel with weighting scheme, described weighting scheme comprises the steps: to provide a weighting function, wherein said weighting function and described weighting function relevant with a critical luminance with the brightness of described pixel as variable; Determine described critical luminance; Find out the pairing weighted value of described pixel intensity by described weighting function; And the chroma of adjusting corresponding described pixel according to described weighted value;
And, described weighting function is one to have the linear function of boundary condition, if described weighting function is represented with W, described critical luminance is represented with Yth, the brightness of described pixel is represented with Yin, the slope of described linear function represents that with S described weighted value represents that with A then described weighting function can be expressed as:
W(Yin)＝S×(Yin-Yth)＝A；
And, if described weighted value does not exceed a weighting limits value, then adjust the chroma of described pixel according to described weighted value, if described weighted value exceeds described weighting limits value, then adjust the chroma of described pixel according to described weighting limits value.
2. the device of a color noise suppressed is characterized in that, comprising:
One weighting determination device receives a luminance input signal and a critical luminance to export a weighted signal;
One weighting restraint device, receive a described weighted signal and a weighting restricting signal, described weighting restricting signal determines a weighting limits value, and, described weighting restraint device is subjected under the situation of described weighting restricting signal control, limit the accurate position output of described weighted signal, with the weighted signal of output smaller or equal to described weighting limits value; And
One weighting device receives described weighting restraint device and exports described weighted signal and at least one chroma input signal to export a chroma output signal;
Wherein, when the brightness value of described luminance input signal hangs down, described weighted signal will make described chroma output signal have lower color saturation, and when the brightness value of described luminance input signal is higher, described weighted signal will make described chroma output signal have higher color saturation;
And described weighting restraint device is a clamper; Described weighting determination device further comprises: a subtracter receives a described luminance input signal and a critical luminance signal to subtract each other output; And a multiplier, receive the output of described subtracter and a slope signal with the described weighted signal of output that multiplies each other; Described weighting device is a multiplier; The weighting function that is adopted is one to have the linear function of boundary condition, if described weighting function represents that with W described critical luminance is represented with Yth, the brightness of described pixel is represented with Yin, the slope of described linear function represents that with S described weighted value represents that with A then described weighting function can be expressed as:
W(Yin)＝S×(Yin-Yth)＝A。
3. the device of color noise suppressed according to claim 2 is characterized in that, described chroma input signal comprises one first chroma input signal and one second chroma input signal.
4. the device of color noise suppressed according to claim 3 is characterized in that, described weighting device further comprises:
One first multiplier receives described first chroma input signal and described weighted signal to export one first chroma output signal; And
One second multiplier receives described second chroma input signal and described weighted signal to export one second chroma output signal.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105025283A (en) * | 2015-08-07 | 2015-11-04 | 广东欧珀移动通信有限公司 | Novel color saturation adjusting method and system and mobile terminal |
| CN105100636A (en) * | 2015-08-11 | 2015-11-25 | 广东欧珀移动通信有限公司 | Image processing method and mobile terminal |
| CN106998456A (en) * | 2017-03-28 | 2017-08-01 | 建荣半导体（深圳）有限公司 | A kind of method of adjustment, device and the picture processing chip of image color saturation |
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| US6542187B1 (en) * | 1998-07-09 | 2003-04-01 | Eastman Kodak Company | Correcting for chrominance interpolation artifacts |
| KR100943274B1 (en) * | 2002-12-20 | 2010-02-23 | 삼성전자주식회사 | Color signal correction device and a method, and image processing system using the same and a method thereof |
| JP4004943B2 (en) * | 2002-12-25 | 2007-11-07 | 富士フイルム株式会社 | Image composition method and imaging apparatus |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105025283A (en) * | 2015-08-07 | 2015-11-04 | 广东欧珀移动通信有限公司 | Novel color saturation adjusting method and system and mobile terminal |
| CN105100636A (en) * | 2015-08-11 | 2015-11-25 | 广东欧珀移动通信有限公司 | Image processing method and mobile terminal |
| CN105100636B (en) * | 2015-08-11 | 2017-11-07 | 广东欧珀移动通信有限公司 | A kind of image processing method and mobile terminal |
| CN106998456A (en) * | 2017-03-28 | 2017-08-01 | 建荣半导体（深圳）有限公司 | A kind of method of adjustment, device and the picture processing chip of image color saturation |
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Effective date of registration: 20200410 Address after: No.1, Duhang 1st Road, Hsinchu City, Hsinchu Science Park, Taiwan, China Patentee after: MEDIATEK Inc. Address before: Hsinchu County, Taiwan, China Patentee before: MStar Semiconductor, Inc. |