CN100375987C - Method for treating color plasma display screen grey - Google Patents

Abstract

The present invention relates to a processing method of a color plasma display screen. Firstly, the gray scale is divided into a low gray scale, a middle gray scale and a high gray scale; secondly, the image information can be detected by programmable logic device FPGA in a statistic image calculation method through a gray scale detection module, and the gray scale characteristics of the current image information is judged by an image processing device so as to carrier out real-time regulation to the image. A nine bit binary digit is formed by extending a sub-field of which the weight is 0.5, the output grade of the gray scale within a low gray scale of 0 to 50 is increased by ten, and error produced in the process of processing can be corrected by an error corrector. The present invention uses a dynamic gray scale correction method, can automatically regulate a gray scale display correction curvature according to the brightness and gray scale situations of a real-time image. Thus, the present invention can make images in different gray scale ranges automatically regulate the gray scale so as to uplift the gray scales. Image details are obviously. Meanwhile, the present invention uses feedback error diffusion to reduce errors generated by looking up a table, so the present invention can ensure image quality to a maximum extent.

Description

A kind of disposal route of color plasma display screen grey

Technical field

The present invention relates to a kind of disposal route of color plasma display screen grey.

Background technology

Color plasma display utilizes gas discharge to realize that image shows in giant-screen flat pannel display field huge competitive power is arranged.Color plasma display is to adopt how sub-field technology to realize that the multi-grayscale of image shows, one two field picture is divided into a plurality of sons field to be realized, a different sons corresponding different weight, different weight is corresponding different keeps umber of pulse, each son time length difference that shows can realize that by sub combination to different weights many grades gray scale of image shows.

Because the CRT monitor part is nonlinear relationship to the light characteristic response, so added Gamma correction at all videos and picture signal, make image linear in gray scale demonstration and brightness, but plasma display device has the linear display characteristic of pair brightness, so in image processing process, will add anti-Gamma correction, in carrying out the Gamma correction process, set up gamma curve table (LUT) by calculating, for traditional anti-gamma revision method is to set up a fixing look-up table, the video and the picture signal of coming from interface passed through 8 look-up tables like this, set up the gray level from 0 to 255, by fitting of two curves, obtain linear relation.

Because the characteristic difference of parameter between the panel of the color plasma display that different vendor produces, therefore video signal is also different by the curve that is fitted after the anti-Gamma correction, if forming the brightness class curve with the anti-gamma curve of fixed single must not be the linear relationship of standard, this just requires the panel of different color plasma displays is adopted different curve values.

Behind anti-Gamma correction look-up table, because many gray levels can be fixed to a specific gray level that gets, because human eye to low gray level partly responsive, darker image section continuous gray-scales will occur and get great-jump-forward and interrupt in visual effect, this has just formed low gray level profile phenomenon.The gray shade scale control needs application of color plasma display is kept the arteries and veins number and is realized.For example 256 gray levels can be divided into 8 sons, export brightness like this and be exactly 2 n power.The people is based on to the visual effect of gray level that luminous stack produces.Though by measuring the pulse of keeping can find color plasma display is linear variation, because the launching curve of fluorescent powder and people's visual effect have caused actual illumination effect right and wrong linear.The output distortion of image and the contour effects of low gray level picture have so just been caused.Therefore, need on input signal discretize basis, adjust corresponding output signal.

The whole bag of tricks such as traditional error diffusion method and overall brightness lifting.Though these methods have solved some problems to a certain extent, actual effect is not fine.If the actual 0-20cd/m that is input as ²The time, only corresponding digital grayscale 1, and actual since in the signal processing to the choice output gray level of decimal at 0-30cd/m ²Just can embody, stereovision naturally will be seldom like this, and image outline is apparent in view, these all since in the plasma display apparatus one keep umber of pulse the minimum brightness unit value decided.

Summary of the invention

The objective of the invention is to overcome the shortcoming of above-mentioned prior art, a kind of gray shade scale that can adjust image dynamically is provided, make gradation of image abundanter, image is the disposal route of color plasma display screen grey more clearly.

For achieving the above object, the technical solution used in the present invention is: at first gray shade scale is divided three different scopes: gray level 0～64 is defined as low gray shade scale; Gray level 65～127 is defined as middle gray shade scale; Gray level 128～255 is defined as high gray shade scale; Pass through gray scale detection module detected image information by programmable logic device (PLD) FPGA (FieldProgrammable Gate Array) with the statistical figure image algorithm then, this gray scale detection module is added up the gray level when first three field signal, calculate three gray-scale datas, adjacent two field data gray level differences in comparing three then, when difference within the limits prescribed the time, utilize image processing apparatus image to be carried out the adjustment of curve characteristic, promptly by expand a weight be 0.5 the son, a weight conversion forms 9 bits through son with 8 bit image data, make the gray scale output stage in 0～50 low tonal range not bring up to 10, proofread and correct the error that the correcting process process produces by error corrector.

Image processing apparatus of the present invention comprises:

A field counter, this counter be by to the counting of the data image signal in, finishes in each redly, green, and Lan Sanse separates statistics, carries out pulse calculating according to 8 bits, adds up the data of number of pulses;

Signal Separation according to the field counter goes out 82 scale codings of three RGBs, counts the redgreenblue separation vessel of monochromatic gray scale by monochrome;

Adjacent two field data gray level differences in three of comparisons, whether control proofreaies and correct according to difference, and the comparer of the scope of proofreading and correct;

Three groups of storage depths are 9 lookup table memories:

First group of lookup table memories is low gray level lookup table memories, and stored data is 9 bit data of the low gamma characteristic of RGB, arranges according to the characteristic of a son weight, and wherein memory space is 256 unit;

Second group of lookup table memories is middle gray level lookup table memories, and stored data is 9 bit data of gamma characteristic in the RGB, arranges according to the characteristic of a son weight, and wherein memory space is 256 unit;

The 3rd group of lookup table memories is the high grade grey level lookup table memories, and stored data is 9 bit data of the high gamma characteristic of RGB, arranges according to the characteristic of a son weight, and wherein memory space is 256 unit.

Error corrector of the present invention is that the data of the storer of tabling look-up are sampled, and sampled value and raw data are compared, and by negative feedback difference is relatively compensated.

The present invention adopts dynamic gray correction method, can be according to the brightness situation of realtime graphic, automatically adjust gray scale and show calibration curve, make the image in different gray shade scale scopes adjust GTG automatically, weight of employing increase is 0.5 son field, and gray level is got a promotion, the details of image is more outstanding, adopt the feedback error diffusion simultaneously, reduce the error of tabling look-up and producing, farthest guaranteed the quality of image.

Description of drawings

Fig. 1 is the brightness output characteristics figure of input signal, and wherein horizontal ordinate is an input signal, and ordinate is for providing signal, and Fig. 1 (a) is the family curve of CRT TV, (b) is the family curve of plasm TV;

Fig. 2 is the dynamic gray correction one-piece construction of the present invention figure;

Fig. 3 is the data flowchart of gray scale detection module;

Fig. 4 is for selecting the process flow diagram of control module;

Fig. 5 is 8 sub son field adjustment structural drawing that expand to 9 son fields;

Fig. 6 is the gray level statistical graph of digital signal Gamma correction, and wherein horizontal ordinate is for proofreading and correct input signal, and ordinate is the brightness output level;

Fig. 7 is the error correction process flow diagram.

Embodiment

Below in conjunction with accompanying drawing the present invention is described in further detail.

Referring to Fig. 1 (a), solid line is the brightness response characteristic of CRT monitor part to the interface signal of input, and curve characteristic is approximately gamma curve, and characteristic relation is a nonlinear relationship; Fig. 1 (b) is the brightness response characteristic of plasma display interface signal, and its curve overlaps with straight line, and is linear.Usually in traditional the transmitting corresponding to the nonlinear curve characteristic of CRT monitor, TV station has loaded the precorrection signal in emission process, to then not needing the precorrection signal in the good PDP display device of the linearity, so need carry out anti-Gamma correction to it.

Referring to Fig. 2,24 binary signals among the figure, each 8 of redgreenblues, pass through lookup table memories, this storer is provided with three groups of look-up tables, and first group of lookup table memories is low gray level lookup table memories, and stored data is 9 bit data of the low gamma characteristic of RGB, characteristic according to a son weight is arranged, and wherein memory space is 256 unit; Second group of lookup table memories is middle gray level lookup table memories, and stored data is 9 bit data of gamma characteristic in the RGB, arranges according to the characteristic of a son weight, and wherein memory space is 256 unit; The 3rd group of lookup table memories is the high grade grey level lookup table memories, stored data is 9 bit data of the high gamma characteristic of RGB, characteristic according to a son weight is arranged, wherein memory space is 256 unit, respectively 3 looks are carried out the equilibrium point setting, three look curves and gamma curve can be fitted on the curve.

The gradation of image detection module is added up the gray level when first three field signal, calculate three gray-scale datas, then by adjacent two field data gray level differences in comparing three, when difference is carried out the adjustment of curve characteristic within the limits prescribed, the present invention with gray scale etc. from dividing three different scopes:

Gray level 0～64: be defined as low gray shade scale;

Gray level 65～127: be defined as middle gray shade scale;

Gray level 128～255: be defined as high gray shade scale;

Different gray scale parts are to eye visual effect difference, and particularly when gray level, gray-level lacks in the image that Gamma correction is crossed, and high gray scale part gamma curve is steep, and gray-level is obvious.

By three look separation vessels three looks are set up different grey scale curve tables, the result who detects by the gray scale detection module judges the currency scope, and different scopes is selected different curve tables.Among the figure, RGB is respectively built three, and each table data reflects different grey scale curve characteristics, at last the data of adjusting is passed through the Flame Image Process memory module, carries out next step computing.

Referring to Fig. 3, by the field counter by to the counting of the data image signal in, finish in each red, green, Lan Sanse separates statistics, carrying out pulse according to 8 bits calculates, from three passages come three road signal R, B, G signal, isolate three chromatic number certificates in every field signal respectively by three look separation vessels, if gray level will be selected low gray level look-up table for use in 0～64 scope, if gray level is the gray scale look-up table between 64～127 then in selecting, if gray level is 128～255 then select high gray scale look-up table.Manifesting different gamma characteristics like this in the different grey-scale scope, increase the gray correction slope of a curve in low gray scale, level is increased, then is curve smoothing in high gray scale.The data of statistical number number of pulses, go out 82 scale codings of three RGBs by three look separation vessels according to the Signal Separation of field counter again, count RGB data in three field signals of monochromatic gray scale by monochrome, the signal that separates after selecting enters inner storage diverter module in different gray scale modules, judge adjustment output by the gray scale thresholding, the judge module position is (Ramdis) among the figure, judge that output is divided into Three Estate: low gradation data, middle gradation data, high gradation data is at last by the output of gray scale output module.

Referring to Fig. 4, the field sync signal that video interface is come is separated the selection signal of judging with the interface clock signal as three, three redgreenblues are separated, calculate the single gray-scale value of redgreenblue respectively by the field counter, select the R that will separate according to field sync signal by field data at last, G, B three chromatic numbers are according to separation, be input in the pulse computing module, draw count results.

Referring to Fig. 5, there is the weight of oneself each son field, and the weighted value minimum is 2 in the 8 sub-field systems, is 255 to the maximum; In the 9 sub-field systems, minimal weight is 0.5, is 128 to the maximum, the luminosity difference of different weight correspondences, because each sub-field brightness is by address period, reset period and keep its brightness, equation expression is as follows:

$L=L_D+L_R$

$\≅\underset{l}{\mathrm{\Σ}}{w}_i{l}_i+L_R$

L _DFor keeping its brightness, L _RFor resetting and address period brightness l _iFor each sub of reality is kept its brightness, $w_i=\{\begin{array}{c}1\\ 0\end{array}$ Point transom field is 1, and not having some transom field is 0.The phase fixed pulse of keeping is equivalent to two to be kept the cycle, the umber of pulse of keeping between them is to be not less than 0 natural number, therefore, if keep umber of pulse is zero, promptly represents gray level 1 with 2 light periods, so, keeping umber of pulse is 1 o'clock (actual have 3 light periods), can represent gray scale 1.5 really, PDP just can express gray level 0.5 in actual displayed like this, and the loss of the gray level of actual displayed can significantly reduce in the gray correction look-up table.

Referring to Fig. 6, wherein square is 9 sub-field systems, triangle is 8 sub-field systems, output gray level output of 0～20 correspondence in the 8 sub-field systems as can be seen from Figure, have only 6 sections gray scale outputs between 0～60, corresponding red square then has 10 sections gray level outputs in the 9 sub-field systems, thereby increases the level of image between low gray area, and details is more obvious.

Referring to Fig. 7, the data of the storer of tabling look-up are sampled, by relatively carrying out anti-Gamma correction, be extended to 9 sub-field systems by look-up table with raw data, by error ratio, input signal is compensated.

Claims (3)

1. the disposal route of a color plasma display screen grey is characterized in that:

1) at first gray shade scale is divided three different scopes: gray level 0～64 is defined as low gray shade scale; Gray level 65～127 is defined as middle gray shade scale; Gray level 128～255 is defined as high gray shade scale;

2) pass through gray scale detection module detected image information by programmable logic device (PLD) FPGA (Field Programmable Gate Array) with the statistical figure image algorithm then, this gray scale detection module is added up the gray level when first three field signal, calculate three gray-scale datas, adjacent two field data gray level differences in comparing three then, when difference within the limits prescribed the time, utilize image processing apparatus image to be carried out the adjustment of curve characteristic, promptly by expand a weight be 0.5 the son, a weight conversion forms 9 bits through son with 8 bit image data, make the gray scale output stage in 0～50 low tonal range not bring up to 10, proofread and correct the error that the correcting process process produces by error corrector.

2. the disposal route of color plasma display screen grey according to claim 1, it is characterized in that: said image processing apparatus comprises:

A field counter, this counter be by to the counting of the data image signal in, finishes in each redly, green, and Lan Sanse separates statistics, carries out pulse calculating according to 8 bits, adds up the data of number of pulses;

Signal Separation according to the field counter goes out 82 scale codings of three RGBs, counts the redgreenblue separation vessel of monochromatic gray scale by monochrome;

Adjacent two field data gray level differences in three of comparisons, whether control proofreaies and correct according to difference, and the comparer of the scope of proofreading and correct;

Three groups of storage depths are 9 lookup table memories:

First group of lookup table memories is low gray level lookup table memories, and stored data is 9 bit data of the low gamma characteristic of RGB, arranges according to the characteristic of a son weight, and wherein memory space is 256 unit;

Second group of lookup table memories is middle gray level lookup table memories, and stored data is 9 bit data of gamma characteristic in the RGB, arranges according to the characteristic of a son weight, and wherein memory space is 256 unit;

The 3rd group of lookup table memories is the high grade grey level lookup table memories, and stored data is 9 bit data of the high gamma characteristic of RGB, arranges according to the characteristic of a son weight, and wherein memory space is 256 unit.

3. the disposal route of color plasma display screen grey according to claim 1, it is characterized in that: said error corrector is that the data of the storer of tabling look-up are sampled, and sampled value and raw data compared, by negative feedback difference is relatively compensated.

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