CN103685867B - Backlight compensation method and device - Google Patents
Backlight compensation method and device Download PDFInfo
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- CN103685867B CN103685867B CN201210337130.5A CN201210337130A CN103685867B CN 103685867 B CN103685867 B CN 103685867B CN 201210337130 A CN201210337130 A CN 201210337130A CN 103685867 B CN103685867 B CN 103685867B
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Abstract
Disclose a kind of backlight compensation method and device.The backlight compensation method includes：The grey level range of backlight image is divided into backlight interval AB, transition interval BC and light interval tri- intervals of CD；The gray level progress BLC that different penalty functions are in different interval pixels to gray level is utilized respectively, wherein being single compensation function for three interval penalty functions.The present invention can improve the gray level of the pixel in backlight area, while expanding the difference in backlight image between the gray level of the pixel in different grey-scale, so that the visual enhancing of whole visual field.
Description
Technical field
The present invention relates to image processing field, relate more specifically to a kind of backlight compensation method and device.
Background technology
In video monitoring system, the information identification to various monitored object is influenceed by illumination, weather condition etc..It is right
In the monitoring image (referred to herein as backlight image) that wherein there is backlight area, BLC, which turns into one, needs that pays close attention to ask
Topic.Because, the too low picture that can cause backlight area of gray level of backlight area is too black, so that the picture of backlight area
The fuzzy even None- identified of the details in face.
BLC is also referred to as BLC or backlight correction, and it can be shot with effective compensation video camera under backlight environment
When the dark defect of main body picture.When introducing BLC function, the main body picture on monitor can be made bright and clear.In backlight
In image procossing, the brightness of the pixel in backlight area is enhanced, and the contrast increase between pixel.But,
In most of BLC schemes, while the brightness of the pixel in backlight area is enhanced, pixel in light region
Brightness is also enhanced, and this make it that whole image brightness is integrally increased, the especially easy transition exposure in light region.Although at some its
In his BLC scheme, the brightness of the pixel only in backlight area is enhanced, but backlight area is extracted in these schemes
The processing in domain also has very high complexity.
The content of the invention
One or more problems in view of the above, the invention provides a kind of novel backlight compensation method and dress
Put.
Backlight compensation method according to embodiments of the present invention includes：The grey level range of backlight image is divided into backlight area
Between AB, transition interval BC and light interval tri- intervals of CD；It is utilized respectively different penalty functions and difference is in gray level
The gray level of interval pixel carries out BLC, wherein being single compensation letter for three interval penalty functions
Number.
BLC device according to embodiments of the present invention includes：Interval division unit, for by the gray scale of backlight image
Level scope is divided into backlight interval AB, transition interval BC and light interval tri- intervals of CD；And BLC unit, use
In being utilized respectively different penalty functions to gray level progress BLC of the gray level in different interval pixels, wherein using
Single compensation function is in three interval penalty functions.
The present invention can improve the gray level of the pixel in backlight area, while expanding in backlight image in difference
Difference between the gray level of the pixel of gray level, so that the visual enhancing of whole visual field.
Brief description of the drawings
From below in conjunction with the accompanying drawings to the present invention embodiment description in the present invention may be better understood, its
In：
Fig. 1 shows the block diagram of BLC device according to embodiments of the present invention；
Fig. 2 shows the flow chart of backlight compensation method according to embodiments of the present invention；
Fig. 3 is the histogram for the distribution situation for showing the pixel grayscale in exemplary backlight image；
Fig. 4 is the schematic diagram of the interval division situation for the grey level range for showing the backlight image shown in Fig. 3；
Fig. 5 is the schematic diagram for the penalty function for showing the gray level for the pixel in each interval shown in Fig. 4；
Fig. 6 is the schematic diagram for showing the method for determining the transitional region BC shown in Fig. 4；
Fig. 7 a and 7b are showing for the correction map picture after backlight image and BLC before showing BLC respectively
It is intended to.
Embodiment
The feature and exemplary embodiment of various aspects of the present invention is described more fully below.Following description covers many
Detail, to provide complete understanding of the present invention.It will be apparent, however, to one skilled in the art that
The present invention can be implemented in the case of some details in not needing these details.Below to the description of embodiment only
Be in order to by show the present invention example come provide to the present invention it is clearer understand.The present invention is not limited to set forth below
Any concrete configuration and algorithm, but cover coherent element, part and calculation under the premise of without departing from the spirit of the present invention
Any modification, replacement and the improvement of method.
Fig. 1 shows the block diagram of BLC device according to embodiments of the present invention.Fig. 2 is shown according to present invention implementation
The flow chart of the backlight compensation method of example.Describe BLC dress according to embodiments of the present invention in detail with reference to Fig. 1 and Fig. 2
Put and method.
As shown in figure 1, BLC device according to embodiments of the present invention includes interval division unit 102 and BLC
Unit 104.Interval division unit 102 by the grey level range of backlight image be divided into backlight interval AB, transition interval BC and
Light interval tri- intervals of CD (that is, perform step S202).BLC unit 104 is using different penalty functions respectively to ash
Spend the gray level progress BLC (that is, performing step S204) that level is in different interval pixels.Wherein, it is interval for backlight
AB, transition interval BC and light interval tri- interval penalty functions of CD are single compensation function.
With reference to the example shown in Fig. 3 and Fig. 4, between area pellucida division unit 102 processing procedure.Specifically, Fig. 3
It is the histogram for the distribution situation for showing the pixel grayscale in exemplary backlight image.Fig. 4 is to show the backlight shown in Fig. 3
The schematic diagram of the dividing condition of the grey level range of image.Wherein, in figs. 3 and 4, abscissa represents gray level, ordinate
Represent the number of the pixel in corresponding gray level.
As shown in figure 4, grey level range shown in Fig. 3 can be divided into three intervals：AB interval (backlight is interval), BC areas
Between (transition interval) and CD regions (light is interval).It is assumed here that, gray level is in the interval pixels of AB and is in backlight figure
In the backlight area of picture, gray level is in the interval pixels of BC and is in the transitional region of backlight image, and gray level is in
Pixel interval CD is in the light region of backlight image.In addition, from figs. 3 and 4 it can be seen that in backlight area gray scale
Level is maximum for the number of G1 pixel, is peak A；Gray level is maximum for the number of G2 pixel in light region, is peak value
B。
, it is necessary to improve the gray level of the pixel in backlight area in BLC processing, while expanding backlight figure
Difference as between the gray level of the pixel in different grey-scale.Based on assumed above, embodiments in accordance with the present invention are given
Go out three and be respectively suitable for backlight area, the single compensation function f1 (x) of transitional region and light region, f2 (x) and f3
(x).Illustrate the processing procedure of BLC unit 104 with reference to Fig. 5.
Fig. 5 is the schematic diagram for the penalty function for showing the gray level for the pixel in each interval shown in Fig. 4.In order to
Expand grey level range, used in an embodiment according to the present invention from 0 to 255 all gray levels (i.e. so that through backlight
The interval minimal gray level of the backlight of compensation is 0, and makes the interval maximum gray scale of the light through BLC for 255).In order to
The contrast of the pixel in transitional region is reduced, the gray level that the interval pixel of transition is in gray level is carried out after BLC
Obtained transition through BLC it is interval [B1, C1) need to meet following condition：
Wherein, NtRepresent that gray level is in the number of transition interval BC pixel, NbRepresent that gray level is in backlight interval CD
Pixel number, NlRepresent that gray level is in the number of light interval AB pixel, Nt+Nb+NlRepresent the picture in backlight image
The total number of element.
After B1 and C1 is determined, you can determine function f1 (x), f2 (x) and f3 (x).Specifically, can be by by Fig. 5
Shown in (A, 0) and (B, B1) two points as the single compensation function f1 (x) for backlight interval AB function curve
Two points solve the single compensation function f1 (x)；Can be by the way that (B, B1) and (C, C1) two points shown in Fig. 5 be made
Single compensation function f2 is solved for two points on the function curve of the single compensation function f2 (x) for excessive interval BC
(x)；And can be by regarding (C, the C1) shown in Fig. 5 and (D, 255) two points as the once benefit for light interval CD
Two on function f3 (x) function curve points are repaid to solve the single compensation function f3 (x).
Then, the Pixel-level for being in backlight interval AB pixel to gray level using single compensation function f1 (x) is carried on the back
Light compensates (that is, obtaining the Pixel-level through BLC by the way that f1 (x) is multiplied with Pixel-level), utilizes single compensation function f2
(x) the transition interval BC Pixel-level progress BLC of pixel is in gray level (that is, by by f2 (x) and Pixel-level phase
It is multiplied to arrive the Pixel-level through BLC), and using single compensation function f3 (x) to picture of the gray level in light interval CD
The Pixel-level of element carries out BLC (that is, obtaining the Pixel-level through BLC by the way that f3 (x) is multiplied with Pixel-level).
In addition, determining method interval BC refers to Fig. 6.In Fig. 6, x-axis represents the gray level of pixel.HIST represents more than certain
The number of pixels of gray level and the ratio of pixel total number.SW (Slide Window, sliding window) represents that HIST integrated value is small
In 0.2 window.When this window obtains maximum, i.e. position interval SWmax is exactly transition interval BC position.
Fig. 7 a and 7b are showing for the correction map picture after backlight image and BLC before showing BLC respectively
It is intended to.The brightness of the pixel in being improved by the present invention in backlight area is can be seen that from Fig. 7 a and Fig. 7 b, while can
To expand the difference in backlight image between the gray level of the pixel in different grey-scale, so that whole visual field is visual
Property enhancing.
The present invention is described by reference to the specific embodiment of the present invention above, but those skilled in the art are equal
Solution, can to these specific embodiments carry out it is various modification, combination and change, without departing from by appended claims or its etc.
The spirit and scope of the present invention that jljl limits.
Step can be performed with hardware or software as needed.Note, without departing from the scope of the invention, can
The step of flow chart provided into this specification adds step, therefrom removal step or changed wherein.In general, flow chart
It is only used to indicate a kind of possible sequence for the basic operation for realizing function.
Embodiments of the invention can utilize the general purpose digital computer of programming, utilize application specific integrated circuit, FPGA
Device, field programmable gate array, system, component and the mechanism of light, chemistry, biological, quantum or nanometer engineering come
Realize.In general, function of the invention can be realized by any means known in the art.Distributed or networking can be used
System, component and circuit.The communication or transmission of data can be wired, wirelessly or through any other means.
It will additionally appreciate, the need for application-specific, one or more of key element shown in accompanying drawing can be by more
Separation or more integrated mode are to realize, or are even removed or are deactivated in some cases.Realization is storable in machine
Journey logic bomb in computer-readable recording medium to allow computer to perform any of the above described method, also the spirit and scope of the present invention it
It is interior.
In addition, any signal arrows in accompanying drawing should be to be considered merely as exemplary rather than restricted, unless separately
There is specific instruction.When the ability that term is also contemplated as making separately or in combination is not known, the combination of component or step also will be by
It is considered to have described.
Claims (10)
1. a kind of backlight compensation method, including：
The grey level range of backlight image is divided into backlight interval AB, transition interval BC and light interval tri- intervals of CD；
The gray level progress BLC that different penalty functions are in different interval pixels to gray level is utilized respectively, wherein
Single compensation function is for three interval penalty functions.
2. backlight compensation method according to claim 1, it is characterised in that transition interval BC's is in gray level
The transition through BLC that the gray level of pixel obtained after BLC it is interval [B1, C1) dynamic range (C1-B1)
The ratio for accounting for gray level 0-255 maximum dynamic range is equal to gray level and is in the transition interval BC number of pixel and accounts for
The ratio of the total number of pixel in the backlight image.
3. backlight compensation method according to claim 1, it is characterised in that light interval CD's is in gray level
The gray level of pixel carries out the dynamic range (255- of the light through BLC interval [C1,255] obtained after BLC
C1 the ratio for) accounting for gray level 0-255 maximum dynamic range is equal to the number that gray level is in light interval CD pixel
The ratio of the total number for the pixel that mesh is accounted in the backlight image.
4. backlight compensation method according to claim 1, it is characterised in that backlight interval AB's is in gray level
The dynamic range (B1-0) that the gray level of pixel carries out the backlight through BLC interval [0, B1] obtained after BLC is accounted for
The number that the ratio of gray level 0-255 maximum dynamic range is equal to the pixel that gray level is in backlight interval AB accounts for institute
State the ratio of the total number of pixel in backlight image.
5. backlight compensation method according to claim 1, it is characterised in that the gray level in the backlight image is in institute
The ratio for stating the total number for the pixel that the number of transition interval BC pixel is accounted in the backlight image is 20%.
6. a kind of BLC device, including：
Interval division unit, for the grey level range of backlight image to be divided into backlight interval AB, transition interval BC, Yi Jiliang
Light interval tri- intervals of CD；And
BLC unit, for being utilized respectively, different penalty functions is in the gray level of different interval pixels to gray level
BLC is carried out, wherein being single compensation function for three interval penalty functions.
7. BLC device according to claim 6, it is characterised in that transition interval BC's is in gray level
The transition through BLC that the gray level of pixel obtained after BLC it is interval [B1, C1) dynamic range (C1-B1)
The ratio for accounting for gray level 0-255 maximum dynamic range is equal to gray level and is in the transition interval BC number of pixel and accounts for
The ratio of the total number of pixel in the backlight image.
8. BLC device according to claim 6, it is characterised in that light interval CD's is in gray level
The gray level of pixel carries out the dynamic range (255- of the light through BLC interval [C1,255] obtained after BLC
C1 the ratio for) accounting for gray level 0-255 maximum dynamic range is equal to the number that gray level is in light interval CD pixel
The ratio of the total number for the pixel that mesh is accounted in the backlight image.
9. BLC device according to claim 6, it is characterised in that backlight interval AB's is in gray level
The dynamic range (B1-0) that the gray level of pixel carries out the backlight through BLC interval [0, B1] obtained after BLC is accounted for
The number that the ratio of gray level 0-255 maximum dynamic range is equal to the pixel that gray level is in backlight interval AB accounts for institute
State the ratio of the total number of pixel in backlight image.
10. BLC device according to claim 6, it is characterised in that the gray level in the backlight image is in
The ratio of the total number for the pixel that the number of the pixel of the transition interval BC is accounted in the backlight image is 20%.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201210337130.5A CN103685867B (en) | 2012-09-12 | 2012-09-12 | Backlight compensation method and device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210337130.5A CN103685867B (en) | 2012-09-12 | 2012-09-12 | Backlight compensation method and device |
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| CN103685867A CN103685867A (en) | 2014-03-26 |
| CN103685867B true CN103685867B (en) | 2017-07-14 |
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| CN107911617A (en) * | 2017-12-27 | 2018-04-13 | 上海传英信息技术有限公司 | Photographic method and device |
| CN108921801B (en) * | 2018-06-26 | 2020-01-07 | 北京字节跳动网络技术有限公司 | Method and apparatus for generating image |
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| CN101325035A (en) * | 2007-06-15 | 2008-12-17 | 深圳Tcl工业研究院有限公司 | Method and system for processing liquid crystal image |
| CN101399924A (en) * | 2007-09-25 | 2009-04-01 | 展讯通信（上海）有限公司 | Automatic exposure method and device based on brightness histogram |
| CN101772799A (en) * | 2007-06-26 | 2010-07-07 | 苹果公司 | Be used to have the technology of the adaptive backlight dimming of video data adjustment simultaneously |
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| WO2007047685A2 (en) * | 2005-10-17 | 2007-04-26 | I2Ic Corporation | Combined video display and camera system |
| KR101295882B1 (en) * | 2009-11-30 | 2013-08-12 | 엘지디스플레이 주식회사 | Liquid crystal display and local dimming control method of thereof |
| TWI483616B (en) * | 2010-08-09 | 2015-05-01 | Chunghwa Picture Tubes Ltd | Display apparatus, display contorl module and display control method |
| CN103177422A (en) * | 2011-12-20 | 2013-06-26 | 富士通株式会社 | Backlight compensation method and system |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101325035A (en) * | 2007-06-15 | 2008-12-17 | 深圳Tcl工业研究院有限公司 | Method and system for processing liquid crystal image |
| CN101772799A (en) * | 2007-06-26 | 2010-07-07 | 苹果公司 | Be used to have the technology of the adaptive backlight dimming of video data adjustment simultaneously |
| CN101399924A (en) * | 2007-09-25 | 2009-04-01 | 展讯通信（上海）有限公司 | Automatic exposure method and device based on brightness histogram |
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