CN105390098A - Method for fitting, compensation and calibration of surface brightness unevenness of liquid crystal screen - Google Patents
Method for fitting, compensation and calibration of surface brightness unevenness of liquid crystal screen Download PDFInfo
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Abstract
The invention relates to a method for the fitting, compensation and calibration of the surface brightness unevenness, caused by backlight unevenness, of a liquid crystal screen. Aiming at a problem that all pixels of a liquid crystal screen display plane are uneven and consistent in brightness because of backlight, the invention proposes three solutions: 1, carrying out compensation and calibration through employing a whole-plane brightness pixel-by-pixel adjustable solution; 2, carrying out the unit line-by-line brightness compensation and calibration at the edge of the crystal display screen according to continuous pixel display lines 3, carrying out compensation and calibration through employing a liquid crystal screen whole-plane brightness function compensation method.
Description
Technical field
The present invention relates to due to the uneven solution of the liquid crystal display surface brightness that backlight is uneven or backlight produces by the impact (the heterogeneous condition in backlight edge) of various boundary.
Background technology
Today, liquid crystal display has developed into ubiquitous condition, liquid crystal display plays indispensable role in the every field such as work, life, amusement of people, it is widely used in mobile phone, iPad, computer, TV and leisure, amusement equipment, and instruction aboard, in market, in public places, in ad system.
The development of liquid crystal makes digital high definition display (1920x1080) become a reality as a kind of standard; Also be the continuous maturation due to liquid crystal technology and progress, 4K ultra high-definition (3820x2160) becomes a reality simultaneously.The digital display technique that liquid crystal is leading is to the future development of higher high definition.
Eighties of last century, the liquid crystal domestic television set used as monomer, personal computer monitor rapidly universal is the typical characteristics of liquid crystal technology maturation.At that time, LCDs is also only confined to the independent use of monomer (separate unit).The beginning of this century, along with the development of liquid crystal technology and display technique, liquid crystal display breaches the limitation that monomer independently uses, and starts to move towards to utilize monomer liquid crystal to shield the field being spliced into liquid crystal curtain wall, and liquid crystal applications field is expanded rapidly.
But liquid crystal itself is not luminous, liquid crystal display needs backlight to provide light source ability display video image.
The backlight of liquid crystal can be divided into cold-cathode fluorescence lamp and LED two kinds from source character, can be divided into side backlight and direct-injection type backlight two kinds from setting point.
1) cold-cathode fluorescence lamp backlight:
Normally used fluorescent light, be a kind of infrabar arc discharge fluorescent light, the temperature of its two end electrodes is higher, is referred to as hot-cathode fluorescent lamp.Because electrode is located at high temperature to work for a long time, cathode disintegration serious (turning black gradually in the two ends of daylight is the performance of cathode disintegration), its life-span is shorter, generally between 5 thousand to 1 ten thousand.
And cold-cathode fluorescence lamp is owing to adopting glow discharge, the temperature of its two end electrodes is relatively low (electric discharge required voltage is relatively high), and cathode disintegration is relatively slow, and the life-span of lamp is long.Generally can reach about 30,000 hours.The research and development success of cold-cathode fluorescence lamp, the development for the liquid crystal display of the backlight that needs to work long hours serves the effect of performing meritorious deeds never to be obliterated.
Cold-cathode fluorescence lamp is as the backlight of liquid crystal display, because its two end electrodes has certain length, this length depends on the length of illumination of cold-cathode fluorescence lamp to a great extent, for the cold-cathode fluorescence lamp that about 1 rice is long, its electrode length generally needs 10 ~ 20 millimeter, as shown in (1) in Fig. 1.And for 46 English inch liquid crystal displays of a widescreen (16:9), the size in its x, y direction is about 1018,573 millimeters, and as shown in Figure 2, therefore, the electrode length at the cold-cathode fluorescence lamp two ends of needs is usually in 18 millimeter.
Cold-cathode fluorescence lamp, as backlight, has side and direct projection two kinds of forms, and the cold-cathode fluorescence lamp of these two kinds of forms is settled along the x direction of liquid crystal display usually, as shown in Figure 3,4.The arrangement mode that Fig. 3 (1) is direct-injection type cold-cathode fluorescence lamp, the arrangement mode that Fig. 4 (1) is side cold-cathode fluorescence lamp.Here it is our exemplary backlit of LCD TV of using in the early time.In such a configuration, owing to needing the length of placing cold-cathode fluorescence lamp two end electrodes, the frame of liquid crystal display is usually more than 30 millimeters.
As monomer use liquid crystal display, people be accustomed to very much LCDs by wide frame round.But Wide frame becomes liquid crystal display and moves towards to splice the obstacle that stands in the breach of curtain wall.In order to avoid too wide frame, in splicing picture, a presumptuous guest usurps the role of the host, and the liquid crystal-spliced screen in ultra-narrow limit arises at the historic moment, and its border width is generally in 6 ~ 7 millimeter.Comparatively speaking, the electrode at cold-cathode fluorescence lamp two ends does not shorten, still the length of 10 ~ 20 millimeters because of the demand on ultra-narrow limit.
In order to obtain relatively uniform liquid crystal display brightness, in direct-injection type backlight, the electrode that method for reflection blocks cold-cathode fluorescence lamp two ends is utilized to become a kind of typical backlight form, as shown in Fig. 1 (2).
2) LED-backlit:
Along with developing rapidly of solid luminescence technology LED, first LED-backlit is used on monomer domestic television set PC monitor.LED-backlit has side and direct-injection type two kinds of forms equally.
Typical direct-injection type LED-backlit as shown in Figure 5.Wherein (1) is the LED array along x, y direction, and (2) are liquid crystal displays, and (3) are backlight diffusion barriers, and (4) are liquid crystal display edge backlit reflectings surface.
Typical side LED-backlit as indicated with 6.Wherein (1) is for arrange LED light source in the x-direction, and (2) are liquid crystal display, and (3) are diffusion barrier, and (4) are light guide plate.The effect of light guide plate converts the line source at its side (top) (be line source depending on LED linear arrangement) to area source, the tight iron diffusion barrier of plane and liquid crystal panel glass on it, bottom surface is generally an inclined-plane, at light source, place is thick, thin at opposite side, and be shaped with small projection in a certain way at its bottom surface or be printed on reflectorized material, make the line source sent from its side, by distance distribution, successively and reflex to liquid crystal display surface as far as possible uniformly, build the area source that liquid crystal display needs.
The backlight of mobile phone liquid crystal screen usually uses LED point backlight form, as shown in (1) in Fig. 7.
Because liquid crystal display is subject to the restriction of shielding body size, any form of light source, and the backlight of any arrangement mode (backlight of today remains and is made up of the discrete luminescence of certain intervals, not disjunctor), have significantly different in the luminescence of liquid crystal display borderline region and reflective condition from middle section.The display brightness of middle section due to the light source arrangement mode around it identical or very close, the light sent is by superposition, homogenize fully, surface brightness relatively consistent (light Fusogenic properties is identical), but, when backlight is at liquid crystal display boundary member, its side roughly has the characteristic of middle section, opposite side is then intercepted by border and can not obtain superposition as middle section light source, homogenize light (the heterogeneous condition in backlight edge), compared with middle section, its surface brightness can produce obvious difference.
The liquid crystal surfactant brightness of direct-injection type cold-cathode fluorescence lamp backlight as shown in Figure 8.Wherein (1) surface brightness that is middle section, (2) are fringe region, and (3) are the mean value of middle section surface brightness, the surface brightness mean value that (4) are fringe region.Owing to there is the impact of cold-cathode fluorescence lamp two end electrodes, liquid crystal surfactant brightness significantly decreases in the left and right sides in x direction, occurs obvious dark space, and the brightness of this dark space reduces about about 30% compared with the brightness of middle section.
The liquid crystal surfactant brightness of direct-injection type LED-backlit as shown in Figure 9, wherein (1) surface brightness that is middle section, (2) be fringe region, (3) are the mean value of middle section surface brightness, the surface brightness mean value that (4) are fringe region.With cold-cathode fluorescence lamp backlight photo ratio, LED limit owing to not having the long electrode of cold-cathode fluorescence lamp, and LED can be aligned on the edge of liquid crystal display as much as possible, and whole screen average brightness improves a lot.But even so, the existence of the heterogeneous condition in backlight edge, still makes the liquid crystal display surface brightness of fringe region can have obvious difference with the brightness of middle section.Meanwhile, all can there is edge effect in LED-backlit on x, y direction, and therefore, liquid crystal display surface there will be the Luminance Distribution situation of similar " flat-top pyramid " formula.
Side cold-cathode fluorescence lamp backlight, the brightness of LED-backlit liquid crystal surfactant are as shown in Figure 10.Wherein (1) is cold-cathode fluorescence lamp backlight backlight, (2) be LED-backlit, (3) be both fringe regions, (side backlight, due to light source, to concentrate on liquid crystal display monolateral, the projection of highlights is had) at the fringe region liquid crystal display surface brightness close to light source, (4) be the surface brightness of both middle sections, (5) be the mean value of both middle section surface brightness, (6) be both the surface brightness mean value of fringe regions.
All backlight design all can be tried one's best, make up the different phenomenon of the surperficial display brightness of the liquid crystal display caused because of zones of different light fusion conditions difference by various method.There is increase backlight diffusion barrier in these methods, increase back light density, promote the spacing of backlight to liquid crystal display; For side backlight, increase light guide plate, improve algorithm and the distribution thereof of light guide plate bottom reflection efficiency and improvement reflective array, etc.
But, in any case, since liquid crystal display is as the monomer of a finite size, objectively there is bound exciton luminescence and the conditioned reflex situation different from middle section.Theoretically, on the monomer of this limited areal, limited height, the means only by making up backlight cannot realize edge and the completely uniform brightness surface of middle section.
The unevenness of liquid crystal surfactant brightness, when using as monomer for liquid crystal, although display effect is not all roses, it is acceptable, this reason that namely today, all liquid crystal displays can be popularized.
But, when people wish that liquid crystal display size is increasing, monomer liquid crystal screen reach 120 English inch still large not time, utilize monomer liquid crystal to be spliced into scheme that liquid crystal display curtain wall just becomes a kind of solution.This utilize multiple monomer liquid crystal tiled display curtain wall in, the uneven phenomenon of the liquid crystal display surface brightness caused due to backlight reason just becomes distinct issues.
The surface of this brightness irregularities is when liquid crystal display is for splicing, dark space due to fringe region is clipped in the middle of the bright areas of middle section, is formed and significantly contrasts, and is very easy to be perceiveed out, moreover, the display effect of the rear whole screen of this dark space grievous injury splicing.
When backlight design is tried one's best, still cannot obtain fully average, etc. bright liquid crystal surfactant, particularly edge brightness and central brightness when there are differences, utilizing method for processing video frequency to carry out compensate for backlight brightness irregularities becomes a kind of effective means.
Summary of the invention
The object of the invention is to solve the brightness of existing monomer liquid crystal screen surfaces inconsistent, make cannot to accomplish to show view picture viewing area in curtain wall in liquid crystal-spliced and reach the problem of uniform luminance, a kind of solution of proposition.This solution provided by the invention will overcome backlight itself because of restricted effectively to screen body size, thickness limits and cannot reach the uniform defect of liquid crystal display surface brightness.
The present invention proposes:
1. brightness point by point compensating coefficient;
2. by-line luminance factor compensates;
3. whole luminance function compensates;
Solution.
Video processing luminance gain compensation principle is the brightness correction K value by arranging some row, before video is sent to liquid crystal display display, carries out luminance gain adjustment according to this group K value that this different brightness value in liquid crystal display surface recorded is arranged in advance.Then, adjusted vision signal is delivered to liquid crystal display display.Due to learn in advance this liquid crystal display position bright, secretly distribute, and can know that in Video processing this moment vision signal will send to the display position of liquid crystal display, this provides the objective condition of compensation just to luminance video gain, makes each vision signal after K value complement is repaid, can send to liquid crystal display display again.Like this, while original video display, compensate for the luminance difference due to backlight restriction generation on this position, make to show the true picture of video image closer to its original input, and will due to backlight light and shade generation difference, and whole screen display effect significantly be improved.
One, the solution of the liquid crystal display " surface brightness pointwise compensation " of the present invention's proposition is as follows:
According to the surface brightness value of the liquid crystal display every bit recorded in advance, calculate its inverse, calculate this luminance compensation K value of liquid crystal display based on this.
Such as, its brightness value is 80%, so the offset calculating this point with the inverse of brightness value is: 1/0.80=1.25 near liquid crystal display edge a bit.Like this, the resultant effect exported after compensating is this brightness: 80%x1.25=1.
As long as record all brightness values of liquid crystal display viewing area in advance, just can obtain whole K values corresponding thereto, and this can be organized K value video send to this liquid crystal display display before it is compensated, make the brightness of every bit consistent with raw video image.
The great advantage of the method is that liquid crystal display brightness pointwise is adjustable, and compensate fineness the highest, effect is best.
The inventive method one is characterized in that: according to the surface brightness value of the liquid crystal display every bit recorded in advance, calculates its 1/K reciprocal, calculates the luminance compensation K value that liquid crystal display is somebody's turn to do based on this.
But the method has obvious defect:
High-definition liquid crystal for 1920x1080 shields, need preparation about 2,000,000 K value penalty coefficients, for 4K ultra high-definition, then need more than 8,000,000 K value penalty coefficients, so jumbo data, not only test and preliminary work amount are greatly to the degree being difficult to bear, and in the design of concrete video processing hardware, the data large like this to capacity can only rely on storage chip to store, and directly cannot be placed on the process chip inside such as FPGA and process.
In fact, in video real time process, 2,000,000, so that 8,000,000 K value offset datas, all need all to read one time at each frame, this is just equally high with the dot frequency of video flowing.Handling capacity large is like this catastrophic to bandwidth resource consumption valuable in system.Meanwhile, such design has to adopt FPGA that is expensive, high throughput performance, and unavoidable cost completely can be high to the unaffordable stage in market.
Because liquid crystal display is systematicness display screen, be exactly that the restriction that is subject to of its backlight illumination design has certain systematicness, regularity, such as, substantially for direct-injection type backlight, the brightness of its zone line relatively all with, brightness comparison in difference compared with middle section of fringe region is large, therefore can consider the brightness only compensating fringe region.
Equally for the liquid crystal display of 1920x1080, submarginal 32 display pixel lines can be adopted to compensate, actual like this compensation count for:
(1920+1080) x (32x2)-(32x32) x4=192000-4096=187,904, count 18.8 ten thousand K values.
The result of such improvement can reduce major part needs data volume to be processed, but:
1) this needs the pixel compensated to exceed 9% of the whole screen image vegetarian refreshments of liquid crystal display, and for the FPGA of today, remain very that googol is according to amount, K value offset data cannot be put into FPGA inside equally and process.
2) in the transversal scanning mode of video flowing, at coboundary and the lower limb of LCD screen, the every bit of these continuous print analyzing spots needs to correct too, therefore in this section of region, equally can be very high to the requirement of bandwidth, so that have a strong impact on the optimizing operation of system.
Two, the solution of the liquid crystal display " compensation of edge brightness by-line " of the present invention's proposition is as follows:
In order to reduce the number of parameters needing compensation correction on the order of magnitude.Method proposes the method for the pixel by-line of liquid crystal display fringe region being carried out to the compensation of brightness K value coefficient.
Liquid crystal display surface brightness compensates and can independently control on " the pixel display line " in region, screen edge.Liquid crystal display is divided into up and down four fringe regions: " upper region ", " lower area ", " left region ", " right region ", each region can control to keep to the side at least 32 pixel display lines of side.
For the pixel on angular bisector, be classified as " upper region " or " lower area " scope, be illustrated in fig. 11 shown below.Define " liquid crystal display top left corner pixel point " and " liquid crystal display lower right corner pixel " region segmentation mode in fig. 11.Actual controllable luminance pixel is " four regions " at least 32 pixel display lines near liquid crystal display display edge side.
Luminance compensation method is as the principle of work of the K value penalty method of the inventive method one, difference is, the method is according to the systematicness of liquid crystal display backlight, regular feature, assuming that on liquid crystal display x direction and y direction, though the surface brightness of its middle section is variant, but this difference is much smaller compared with fringe region, belong to the error of time one-level, negligible.The region that only edge luminance difference is larger compensates and corrects.
Like this, K value offset data reduces greatly, only needs 32 pixel display lines at the close liquid crystal display edge in process four regions, only needs data to be processed from 200 (800) ten thousand, has dropped to and altogether only needed 32x4=128, reduced nearly 20,000 times.This results in a great advantage is, these data can stored in the internal storage of FPGA preciousness, and without any need for exterior I O resource.Not only avoid the bandwidth bottleneck that high-capacity K value offset data causes, make Video processing more effective, cost also declines to a great extent simultaneously.
The inventive method two is characterized in that: the luminance difference of centralized compensation, calibrating crystal platen edge limited pixel line (as 32 lines), liquid crystal display is divided into up and down four fringe regions: " upper region ", " lower area ", " left region ", " right region ", for the pixel on angular bisector, be classified as " upper region " or " lower area " scope, adopt brightness K value complement to repay, calibrate.Be further characterized in that: for the situation of centralized compensation, calibrating crystal platen edge N (as 32) line, it compensate, calibrate that the quantity of K value parameter reduces to 4xN (as 32)
Individual, and directly can store in the storage resources of limited FPGA, avoid reading compensation, calibration parameter data from outside in Video processing.
And in fact, in the brightness distribution curve of liquid crystal display, except in x direction, be all curve distribution in y-direction, be namely similar to the oval ball top of " Bird's Nest ", as shown in figure 12. simultaneouslyBoth synthesis are Luminance Distribution curved surfaces.
Therefore, if only arrange a parameter to every bar pixel display line, the brightness curve change on this display line will be neglected, cause the coarse phenomenon of compensation correction.For example, for " upper region " and " lower area ", this method, although every bar pixel display line in y-direction can brightness distribution curve on perfect matching y direction, but in the x direction, this K value offset is a definite value, there is larger difference with the brightness distribution curve of reality.
Therefore, the disadvantage of this method is: on frame, and near bight, correction error is very large.
Although every bar pixel display line in four regions can be compensated calibration in the method, on angular bisector, is the joint portion of two kinds of different compensation calibrations.On this crest line, be not interrupted although compensate, but because it is that the not necessarily equal fixed value compensation K value coefficient in two, x and y direction compensates, their collecting on this crest line can produce certain difference, namely on crest line, " transition of compensation " may be discontinuous, can produce a sudden change.If carry out this compensation of matching with a function, so on this rib, function is non-differentiable, and namely its derived function is discontinuous.
It is to be noted: this " sudden change " on crest line, the brightness matching for actual video and backlight is wrong, because the variation tendency of the Luminance Distribution of reality, this crest line is continuous print.Compensate K value quantity this is because reduce, every bar pixel display line only has a K value caused for compensating, correcting.And once correction there occurs mistake, even if on some respective regions joint lines, naturally can knowledge be perceiveed, cause the distortion of original input video image.
Three, the solution of the liquid crystal display " whole luminance function compensates " of the present invention's proposition is as follows:
The method one, the method two that propose due to the present invention have its obvious advantage, and also there is inevitable shortcoming, this method three proposes simultaneously:
1, both can use less parameter, to facilitate directly in FPGA internal arithmetic, and not need the support of the exterior storage relying on high-throughput;
2, again can more ideally to the uneven effective compensation that compensates of Luminance Distribution in any region such as central authorities, edge, bight being included in liquid crystal display viewing area;
3, finally the luminance compensation that also will reach in any region is all nature continuous print, penalty function all everywhere continuous can leading in whole field of definition,
Method compensate the uneven solution of liquid crystal display backlight.
The reality " brightness distribution curve " of liquid crystal display is the intrinsic brilliance distributed data measured on liquid crystal display, and it can be similar to and be summarized as twice curve, and its equation is:
Ax^2+Bxz+Cz^2+Dx+Ez+F=0
Wherein x is position, and z is brightness data.
If equidistantly advanced to y direction by this curve in the x-direction, so this twice curve will change, that is, the coefficient of above-mentioned equation will change, and reflect brightness change in the x-direction on certain y position.
If brightness summit is wherein set to 100%, remaining brightness will progressively lower than 100%, and simultaneously, both sides brightness in the x-direction will be more and more lower.
Finally, twice curve of reaction brightness advances in y direction in the x-direction, can sketch the contours of twice curved surface; Vice versa, twice curve based on y direction, and advance to x direction, result is identical.
Solve or matching twice toroidal function: brightness (Brightness)=f (x, y), comparatively accurately the intrinsic brilliance distribution on matching liquid crystal display surface.
The brightness Quadratic Surface Equation of a structure standard:
Ax^2+By^2+Cz^2+Dxy+Exz+Fyz+Gx+Hy+Iz+J=0.
Wherein, variable x and y is to the x for pixel on liquid crystal display, y coordinate, and as shown in Figure 2, z is brightness value.
If gone and this twice surface intersection by any one plane, such as, use plane y=0 and this twice surface intersection, now, intersecting lens is twice curve in the x-direction.
Above-mentioned curved surface be one can the Quadratic Surface Equation of the unusual brightness distribution function of closing to reality, amount to the adjustable parameters containing 10 standards.
If true origin is moved to the center of liquid crystal display, so P
0the point of (x=0, y=0) is just on the central point of liquid crystal display.Suppose that the brightness that this puts is 100%, be 1.So, substitute in equation
After (x, y, z)=(0,0,1),
Obtain: C+I+J=0[equation 1]
First consider that line of x direction of central cross line, y=0 here.
For 1920 pixel-parameters of transverse direction, suppose that leftmost is x=-960, rightmost is x=+960.
And the brightness value recording that point of left side x=-960 is in advance 71%, so use
(x,y,z)=(-960,0,0.71)
Substitute into, obtain:
A*960*960+C*0.71*0.71-E*960*0.71-G*960+I*0.71+J=0[equation 2.0]
And with brightness value (here first suppose brightness the be symmetrical) substitution of that point of the right x=+960,
(x, y, z)=(960,0,0.71) substitutes into, and obtains:
A*960*960+C*0.71*0.71+E*960*0.71+G*960+I*0.71+J=0
[equation 2.1]
Deduct [equation 2.0] with [equation 2.1], obtain:
E*0.71+G=0[equation 2.2]
In above-mentioned three equations, because the 3rd equation is the derivation of the first two equation, be therefore linear correlation.
In order to Relationship of Coefficients is clear, we get [equation 2.1] and [equation 2.2].
Equally, consider that clue display line of y direction of central cross line, also can obtain two equations:
In like manner, substitute into the top y=+540:
(x, y, z)=(0,540,0.71), obtains:
B*540*540+C*0.71*0.71+F*540*0.71+H*540+I*0.71+J=0
[equation 3.1]
Try to achieve y direction that equation put bottom again, and synthesize with [equation 3.1], obtain:
F*0.71+H=0.[equation 3.2]
Illustrate: for expressing conveniently, the brightness of the most termination of above-mentioned x, y is set to 0.71, actual solve in should use intrinsic brilliance measurement data, expression formula is here corresponding to be modified.
First, through measuring, the distributed data at liquid crystal display surface brightness is easily obtained.
Then, 10 parameters of above-mentioned twice curved surface, under different numerical value, will build a Quadratic Surface Equation formula, produce " the Luminance Distribution fitting data " of a pointwise.
For this " Luminance Distribution fitting data " difference with " Luminance Distribution real data " pointwise, get its square, that is, utilize least square ratio juris.
Above-mentioned square of data pointwise is all added, tries to achieve the minimum value of a quadratic sum.Those 10 parameters under this minimum value are exactly the required parameter obtained of luminance compensation twice curved surface.
Use the softwares such as MATLAB computer numerical analysis to the traversal computing of above-mentioned various dimensions, play the ability of the large data operation of outer computer, finally obtain the concrete numerical value of 10 parameters.
Although the numerical evaluation traversal computing of 10 parameters is complicated processes, in step demonstration above, obtain the relation between some coefficients, will greatly reduce computing machine and carry out the traversal scope of various dimensions computing like this.
Due to 5 equations about Relationship of Coefficients obtained above, be all linearly incoherent, that is, by these Relationship of Coefficients formulas, the computing of computing machine 10 dimension traversal has directly been reduced to the traversal computing of 5 dimensions.
In simple terms, according to [equation 1], C+I+J=0, for certain specific I and J, so C is a value determined, so C just without the need to add dimension traversal computing among.
For the above-mentioned brightness Quadratic Surface Equation mentioned:
Ax^2+By^2+Cz^2+Dxy+Exz+Fyz+Gx+Hy+Iz+J=0.
After all 10 parameters are all concrete numerical value, for the point (x, y) that certain on liquid crystal display is concrete, only remaining variable z, i.e. brightness, other be all constant c, that is:
c=Ax^2+By^2+Dxy+Gx+Hy+J
So equation becomes:
Cz^2+(Ex+Fy+I)z+c=0.
Order:
a=C
b=Ex+Fy+I
Then, the quadratic equation of standard has been become:
az^2+bz+c=0.
The solution of such z is very simple.
z=
After obtaining z, the brightness value that actual needs compensates is the inverse of z, that is:
Offset=1/z.
The inventive method three is characterized in that: the brightness irregularities produced due to backlight reason for each pixel of liquid crystal display display plane, inconsistent situation, the method adopting liquid crystal display whole luminance function to compensate is compensated, it is characterized in that: twice curve simulating brightness in the x-direction, and advance to y direction, build twice curved surface of a whole screen brightness, make it in compensation, the quantity of involved corrected parameter considerably less (as only 10 parameters) during luminance difference in calibrating crystal screen plane, and directly can store in the storage resources of limited FPGA, avoid reading from outside in Video processing compensating, calibration parameter data.Be further characterized in that: being included in any regions such as the central authorities of liquid crystal display viewing area, edge, bight can more ideally to the uneven effective compensation that compensates of Luminance Distribution, at its whole curved surface codifferential everywhere continuous; Meanwhile, make the brightness curved surface everywhere continuous (its curved surface differential is continuous print) after compensating, do not produce sudden change and step.
FPGA is inner only stores 10 data, that is, millions of or hundreds thousand of parameters have originally been reduced to and only had 10.Like this, data just can be stored in the inside of FPGA completely, in process in real time, do not need waste bandwidth to read data from outside.
Because by the matching that the Quadratic Surface Equation of standard carries out, therefore no matter in the centre of screen, edge or corner, all perfectly can compensate brightness.
Quadratic Surface Equation only has unique one, according to maxim, within the scope of its field of definition, and everywhere continuous and everywhere can leading.Therefore, the transition sudden change of gamma correction can not be there is.
Accompanying drawing illustrates:
Fig. 1, liquid crystal display take cold-cathode fluorescence lamp as the backlight schematic diagram of light source;
The display plane of Fig. 2, liquid crystal display and coordinate axis definition thereof;
Fig. 3, direct-injection type cold-cathode fluorescence lamp back light arrangement schematic diagram;
Fig. 4, side cold-cathode fluorescence lamp back light settle schematic diagram;
Fig. 5, direct-injection type LED-backlit arrangement schematic diagram;
Fig. 6, side LED backlight light source settle schematic diagram;
Fig. 7, mobile phone backlight light source settle schematic diagram;
Fig. 8, direct-injection type cold-cathode fluorescence lamp backlight liquid crystal screen surfaces Luminance Distribution schematic diagram;
Fig. 9, direct-injection type LED-backlit liquid crystal display surface brightness distribution schematic diagram;
Figure 10, side cold-cathode fluorescence lamp and LED-backlit liquid crystal display surface brightness distribution plan;
Figure 11,32 pixel display line x, in y fluidic junction, pixel divides figure;
Figure 12, along the brightness curve schematic diagram on liquid crystal display y direction.
Claims (3)
1. for the brightness irregularities that each pixel of liquid crystal display display plane produces due to backlight reason, inconsistent situation, the method adopting liquid crystal display whole luminance function to compensate is compensated, it is characterized in that: twice curve simulating brightness in the x-direction, and advance to y direction, build twice curved surface of a whole screen brightness, make it in compensation, the quantity of involved corrected parameter considerably less (as only 10 parameters) during luminance difference in calibrating crystal screen plane, and directly can store in the storage resources of limited FPGA, avoid reading from outside in Video processing compensating, calibration parameter data.Be further characterized in that: being included in any regions such as the central authorities of liquid crystal display viewing area, edge, bight can more ideally to the uneven effective compensation that compensates of Luminance Distribution, at its whole curved surface codifferential everywhere continuous; Meanwhile, make the brightness curved surface everywhere continuous (its curved surface differential is continuous print) after compensating, do not produce sudden change and step.
2. be unit by-line luminance compensation, calibration at liquid crystal display edge by continuous print pixel display line.It is characterized in that: the luminance difference of centralized compensation, calibrating crystal platen edge limited pixel line (as 32 lines), is divided into four fringe regions up and down by liquid crystal display: " upper region ", " lower area ", " left region ",
" right region ", for the pixel on angular bisector, is classified as " upper region " or " lower area " scope, adopts brightness K value complement to repay, calibrate.Be further characterized in that: for the situation of centralized compensation, calibrating crystal platen edge N (as 32) line, it compensate, calibrate that the quantity of K value parameter reduces to 4xN (as 32)
Individual, and directly can store in the storage resources of limited FPGA, avoid reading compensation, calibration parameter data from outside in Video processing.
3. the solution that whole brightness pointwise is adjustable is compensated, and it is characterized in that: according to the surface brightness value of the liquid crystal display every bit recorded in advance, calculates its 1/K reciprocal, calculate the luminance compensation K value that liquid crystal display is somebody's turn to do based on this.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410452531.4A CN105390098A (en) | 2014-09-05 | 2014-09-05 | Method for fitting, compensation and calibration of surface brightness unevenness of liquid crystal screen |
| CN201810158425.3A CN108281121A (en) | 2014-09-05 | 2014-09-05 | Show line for unit by-line luminance compensation, the method for calibration by continuous pixel in liquid crystal platen edge using method for processing video frequency |
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| CN106409206A (en) * | 2016-09-21 | 2017-02-15 | 北京京东方专用显示科技有限公司 | Display image brightness compensation method and compensation device |
| CN109686297A (en) * | 2018-12-25 | 2019-04-26 | 上海创功通讯技术有限公司 | A kind of LED light connection circuit and display |
| WO2020024479A1 (en) * | 2018-07-30 | 2020-02-06 | 武汉华星光电半导体显示技术有限公司 | Bright spot compensation method and device for curved screen |
| CN111292253A (en) * | 2019-12-11 | 2020-06-16 | 新绎健康科技有限公司 | Human body glow image calibration method and device |
| CN113379752A (en) * | 2021-04-09 | 2021-09-10 | 合肥工业大学 | Image segmentation algorithm for double-layer liquid crystal display |
| CN116381983A (en) * | 2022-12-29 | 2023-07-04 | Tcl华星光电技术有限公司 | Luminance compensation method and device for display panel and display panel |
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| CN111292253B (en) * | 2019-12-11 | 2023-04-18 | 新绎健康科技有限公司 | Human body glow image calibration method and device |
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