CN101521001A - Color correction method and device for display device - Google Patents

Abstract

A color correction method of a display device is suitable for adjusting the output color of the display device. The color correction method comprises the steps of firstly, displaying a plurality of images on a panel of the display device, and measuring chromatic values and brightness values of the plurality of images to obtain the color display characteristics of the display device. Secondly, according to the color display characteristics, a corresponding color matrix is generated, wherein the color matrix is located in the linear color space of CIE XYZ. Then, the color matrix and the gain matrix are operated to output an output matrix. The gain matrix is then adjusted so that the output matrix is substantially the same as the target matrix. Finally, the element values obtained in the adjusted gain matrix are referred to set the display device so as to correct the output color of the display device.

Description

The color correcting method of display device and device

Technical field

The invention relates to a kind of color correcting method, refer to a kind of color correcting method of display device and relevant colour correcting apparatus thereof especially.

Background technology

Along with making rapid progress of science and technology, display device on the market is towards development in pluralism, common person such as iconoscope TV, LCD screen, plasma television and back projection TV etc.Because the image-forming principle of various device is not quite similar, the color that is showed is a difference to some extent.Therefore, the color rendition usefulness that how to improve display device often think for the deviser and problem.Signal Processing at the picture signal color rendition of display device comprises following two main projects.

At first, various display device have unique color display characteristic, and chromaticity coordinates construction in color space of the redness of its demonstration, green and blue three primary colors image goes out specific colour gamut (Color gamut) scope.For the look appearance of the picture signal imaging that makes the input of each display device reaches correctness and consistance, therefore, the color display characteristic that must cooperate display device utilizes the mode of colour gamut correspondence, makes the shown image of display device present identical look appearance.

Secondly, transfer to the picture signal of display device, its GTG value and signal intensity exist nonlinear relation usually, and this phenomenon is called the Gamma characteristic.This Gamma characteristic can be by being the function representation of nonlinear curve.When the image pixel data signal of input is x, the brightness of image pixel is to present x γ, and γ is the Gamma exponential quantity, and this γ value is with the change of the pairing specification of picture signal.Linear for the intensity of the image pixel that makes reproduction and original image signal, display device has graphics processing unit usually and proofreaies and correct picture signal is carried out Gamma.Generally speaking, Gamma proofreaies and correct two kinds of methods.One is to use the mode of digital signal processing (DSP, Digital Signal Processing), calculates and the corresponding GTG value of input value with the GTG functional expression.Two are to use look-up table (Look-up table) to obtain and the corresponding GTG value of input value.Look-up table is that the GTG value before and after will changing is in advance calculated, and builds and shows in firmware or hardware, when needs carry out the Gamma timing, can directly utilize the input value correspondence to find out output valve.

See also Fig. 1, this figure is the system architecture synoptic diagram of the display device 1 of known technology.As shown in Figure 1, image source S inputs to display device 1 with picture signal, and this picture signal is to carry out signal conversion processes via graphics processing unit 10 earlier, exports panel 16 again to and shows.Graphics processing unit 10 comprises Gamma modular converter 12 and colour gamut respective modules 14.Gamma modular converter 12 and colour gamut respective modules 14 are Gamma conversion and corresponding programs of colour gamut of carries out image signal respectively.Gamma modular converter 12 and the colour gamut respective modules 14 performed required parameters of picture signal conversion are after display device 1 assembling is finished, and are set by color correction program.

In the prior art, color correction program comprises that driving display device 1 shows the whole white image on panel 16, and measure the chromatic value and the brightness value of this whole white image, to obtain the Gamma characteristic and the gamut range of display device 1, then, via measured chromatic value and brightness value, set the parameter of this Gamma modular converter and the parameter of gamut range.After having set parameter, drive display device 1 once more and on panel 16, show the whole white image, and measure the chromatic value and the brightness value of this whole white image, to confirm whether to reach the reference color temperature of target, if reached the reference color temperature of target, then finish the parameter setting of setting display device 1, if the reference color temperature of miss the mark still, then continue to set the parameter of required setting in the display device 1, till the colour temperature of display device 1 reaches the reference color temperature of this target.Yet this kind color correction program is to carry out linear R GB gain at the whole white image to adjust, and can make and have only the whole white image to reach the reference color temperature of target at last that remaining GTG can't reach the reference color temperature of target.

Summary of the invention

The objective of the invention is to be to provide a kind of colour correction (Color correction) method and relevant colour correcting apparatus of display device, it is by carrying out chromatic adaptation program (Chromatic adaptationprocess), adjust the chromatic characteristic of display device, the picture colour temperature that makes display device export meets pre-provisioning request.

The present invention provides a kind of color correcting method of display device, be applicable to the output color of adjusting display device, this display device has graphics processing unit in order to control this output color, and this color correcting method comprises the following steps: to show that at least one picture signal is on the panel of this display device; Measure this picture signal to obtain color matrices, wherein this color matrices is to be arranged in linear space; In this linear space, this color matrices and gain matrix are carried out computing, to export an output matrix; Adjust this gain matrix, make this output matrix identical in fact with objective matrix; And, set this graphics processing unit to proofread and correct the output color of this display device according to this gain matrix.

The present invention also provides a kind of colour correcting apparatus, be applicable to the output color of adjusting display device, this display device has graphics processing unit in order to control this output color, and this colour correcting apparatus comprises: colorimeter is used for measuring the shown at least one picture signal of this display device; The display characteristic computing module is used for calculating this measured picture signal of this colorimeter, and to produce color matrices, wherein this color matrices is to be arranged in linear space; Module is calculated in chromatic adaptation, is used in this linear space, this color matrices and gain matrix is carried out computing, to export an output matrix; Adjustment unit is used for adjusting this gain matrix and makes this output matrix identical in fact with objective matrix; And setting module, be used for according to this gain matrix, set this graphics processing unit to proofread and correct the output color of this display device.

Above general introduction and ensuing detailed description and accompanying drawing all are to reach mode, means and the effect that predetermined purpose is taked in order to further specify the present invention.And relevant other purpose of the present invention and advantage, will follow-up explanation and graphic in set forth.

Description of drawings

Fig. 1 is the system architecture synoptic diagram of the display device of known technology;

Fig. 2 carries out the system architecture synoptic diagram of first embodiment of colour correction to display device for disclosed colour correcting apparatus;

Fig. 3 is the flow chart of steps of first embodiment of disclosed color correcting method;

[drawing reference numeral explanation]

1,3: display device

10,30: graphics processing unit

12,32:Gamma modular converter

14,34: the colour gamut respective modules

16,36: panel

2: colour correcting apparatus

20: colorimeter

22: the display characteristic computing module

24: module is calculated in chromatic adaptation

241: chromatic adaptation matrix decision unit

243: adjustment unit

245: color space transformation/computing unit

26: setting module

28: control module

S: image source

Embodiment

At first, see also Fig. 2, this figure is the system architecture synoptic diagram that disclosed 2 pairs of display device of colour correcting apparatus 3 are carried out first embodiment of colour correction (Color correction).Colour correcting apparatus 2 is applicable to the transformational relation of the input and output picture signal of adjusting display device 3, so that picture color that display device 3 is exported and colour temperature meet pre-provisioning request.

As shown in Figure 2, display device 3 has panel 36 and graphics processing unit 30.By the picture signal of outside input and display device 3, will carry out signal conversion processes through graphics processing unit 30 earlier, export panel 36 again to and show.Graphics processing unit 30 comprises Gamma modular converter 32 and colour gamut respective modules 34 again.Gamma modular converter 32 and colour gamut respective modules 34 are Gamma conversion and corresponding programs of colour gamut (Color gamut) of carries out image signal respectively.Above-mentioned Gamma modular converter 32 and colour gamut respective modules 34 performed picture signal transformational relations (Conversion relation) are after display device 3 assemblings are finished, and carry out color correction program by 2 pairs of display device of colour correcting apparatus 3 and are set.

Colour correcting apparatus 2 has control module 28, control module 28 is to drive display device 3 according to preset program, make display device 3 show the image of multicolour on panel 36, the image of described multicolour comprises whole white image, whole red image, full green image and full blue image.Among Fig. 2, colour correcting apparatus 2 has colorimeter (Colorimeter) 20, in order to receive panel 36 shown whole white image, whole red image, full green image and full blue image, with chromatic value (Chromatic value) and the brightness value optical characteristics such as (luminance) of measuring these images.

Among Fig. 2, colour correcting apparatus 2 comprises display characteristic computing module 22, chromatic adaptation calculating module 24 and setting module 26, and chromatic adaptation is calculated module 24 and comprised the decision of chromatic adaptation matrix unit 241, adjustment unit 243 and color space transformation/computing unit 245 again.Subsidiary one carry be, colour correcting apparatus 2 can be implemented by computer system, and display characteristic computing module 22 wherein, chromatic adaptation are calculated module 24, setting module 26 and control module 28 and can be utilized software collocation computer system s operation control resource to realize its function.Press, the performed function of each module of colour correcting apparatus 2 will cooperate color correcting method to be specified in down.

Then, see also Fig. 3, this figure is the method step process flow diagram of first embodiment of disclosed color correcting method.Wherein Xiang Guan system architecture is please consulted Fig. 2 simultaneously.As shown in Figure 3, this color correcting method comprises the following steps.

At first, control module 28 drives display device 3 and show multiple image on panel 36, colorimeter 20 receives and measures the chromatic value and the brightness value of this multiple image, to obtain the color display characteristic of display device 3, described color display characteristic comprises colour gamut (Color gamut) scope and GTG (Gamma) performance (step S300) of panel 36.

According to an embodiment, step S300 also comprises the following steps:

The first, control module 28 drives display device 3 and show the whole white image on panel 36.Colorimeter 20 receives and measures the chromatic value and the brightness value of this whole white image, and exports measured value to display characteristic computing module 22, to obtain the gamut range of display device 3.

The second, control module 28 drives display device 3 shows whole red image, full green image and complete all GTGs of blue image on panel 36 image.Colorimeter 20 receives and measures the chromatic value and the brightness value of this whole red image, this full green image and these complete all gray scale images of blue image, and exports measured value to display characteristic computing module 22, to obtain the GTG performance of display device 3.

Secondly, display characteristic computing module 22 produces color matrices, so that represent obtained color display characteristic (step S302) with this color matrices according to the obtained color display characteristic of step S300.Described color matrices is the linear color space that is arranged in CIE XYZ, in order to the color show state of presentation video signal through graphics processing unit 30.At this, [XYZ] represents described color matrices with matrix.Then, display characteristic computing module 22 exports color matrices among the chromatic adaptation calculating module 24 again.

With an embodiment, suppose that this color matrices is that backlight in display device 3 is resultant under the condition of colour temperature 6500k (D65), then, chromatic adaptation is calculated module 24 and is carried out chromatic adaptation program (ColorAdaptation Process), color matrices [XYZ] and gain matrix are carried out computing, to export an output matrix [X ₁Y ₁Z ₁] (step S304).Again, in carrying out the chromatic adaptation program, can be by adjusting the matrix element in the gain matrix, make output matrix [X ₁Y ₁Z ₁] (for example: colour temperature 5000K, D50) pairing objective matrix [X equal the target colour temperature in fact _tY _tZ _t].In addition, described chromatic adaptation program also comprises following three steps:

The first, chromatic adaptation is calculated module 24 and with transition matrix (Conversion matrix) this color matrix conversions is arrived IPT LMS color space, and to obtain first color conversion matrix [LMS], the mathematics that is carried out is changed as the formula (1):

$\left[\begin{array}{c}L\\ M\\ S\end{array}\right]=\left[\begin{array}{ccc}0.8951& 0.2664& -0.1614\\ -0.7502& 1.7135& 0.0367\\ 0.0389& -0.0685& 1.0296\end{array}\right]\·\left[\begin{array}{c}X\\ Y\\ Z\end{array}\right]\·\·\·\·\·\·\left(1\right)$

Again, in the formula (1), transition matrix is BradfordMatrix.This case inventor utilize BradfordMatrix with color matrices by CIE XYZ color space transformation to IPT LMS color space.

The second, resulting first color conversion matrix and chromatic adaptation matrix (Color adaptationmatrix) are carried out computing, to obtain second color conversion matrix, the mathematics that is carried out is changed as the formula (2).

$\left[\begin{array}{c}L\′\\ M\′\\ S\′\end{array}\right]=\left[\begin{array}{ccc}\frac{L_{\mathrm{CT}}}{L_{D65}}& 0& 0\\ 0& \frac{M_{\mathrm{CT}}}{M_{D65}}& 0\\ 0& 0& \frac{S_{\mathrm{CT}}}{S_{D65}}\end{array}\right]\·\left[\begin{array}{c}L\\ M\\ S\end{array}\right]\·\·\·\·\·\·\left(2\right)$

This chromatic adaptation matrix is with pairing first color conversion matrix of initial color temperature value D65 [LMS], is adjusted into pairing second color conversion matrix of target color temperature value D50 [L ' M ' S '].As the formula (2), the chromatic adaptation matrix comprises the LMS distribution proportion (L of initial color temperature value D65 _D65, M _D65, S _D65), and the LMS distribution proportion (L of target color temperature value _CT, M _CT, S _CT).(L herein _D65, M _D65, S _D65) and (L _CT, M _CT, S _CT) can obtain by consulting given data.

The 3rd, by inverse transform matrix (Inverse conversion matrix), this second color conversion matrix [L ' M ' S '] is changed back CIE XYZ color space, to obtain output matrix [X ₁Y ₁Z ₁], this inverse transform matrix inverse matrix that is Bradford Matrix wherein.

Above first step can reduce formula (3) to the mathematics conversion that third step carried out, and wherein matrix A and matrix B M are that representative color adapts to matrix and transition matrix (that is Bradford Matrix) respectively.

$\left[\begin{array}{c}{X}_1\\ Y_1\\ Z_1\end{array}\right]={\left[\mathrm{BM}\right]}^{-1}\left[A\right]\left[\mathrm{BM}\right]\left[\begin{array}{c}X\\ Y\\ Z\end{array}\right]\·\·\·\·\·\·\left(3\right)$

According to one embodiment of the invention, the chromatic adaptation matrix decision unit 241 that is arranged at colour correcting apparatus 2 inside is to store gain matrix ([BM] in order to cooperate ^-1* [A] * [BM]).And color space transformation/computing unit 245 is to be coupled to chromatic adaptation matrix decision unit 241.Color space transformation/computing unit 245 is converted to IPT XYZ color space with color matrices with transition matrix BM, produce first color conversion matrix, and first color conversion matrix and chromatic adaptation matrix A carried out computing, to produce second color conversion matrix, at last, again with second color conversion matrix with inverse transform matrix B M ^-1Change back CIE XYZ color space, to obtain output matrix.

Then, color space transformation/computing unit 245 is judged this output matrix [X ₁Y ₁Z ₁] whether with predetermined objective matrix [X _tY _tZ _t] identical, if when inequality, then calculate adjustment unit 243 in the module 24 and adjust matrix element in the chromatic adaptation matrix A, until the output matrix [X of institute by being arranged at chromatic adaptation ₁Y ₁Z ₁] and predetermined objective matrix [X _tY _tZ _t] identical (step S306).According to one embodiment of the invention, color space transformation/computing unit 245 is judged output matrix [X ₁Y ₁Z ₁] and this objective matrix [X _tY _tZ _t] whether identical, also can pass through [X ₁Y ₁Z ₁] be converted to Y _XyRepresentation judge, in other words, by the output matrix [X of chromatic adaptation program institute ₁Y ₁Z ₁] Y with a correspondence _XyValue (being constant), and objective matrix [X _tY _tZ _t] also have another corresponding Y _XyValue, therefore, can be by comparing this two Y _XyDifference whether less than critical value or equate, with decision output matrix [X ₁Y ₁Z ₁] and predetermined objective matrix [X _tY _tZ _t] whether identical.Described output matrix [X ₁Y ₁Z ₁] and this objective matrix [X _tY _tZ _t] whether identical determination methods is an example only, use elaboration the present invention, but the present invention is not as limit.In addition, color matrix conversions is to Y _XyKnown to those skilled in the art the knowing of process, so do not give unnecessary details in addition at this.

At last, setting module 26 calculates the module 24 inner gain matrixs of finishing ([BM] of adjusting according to chromatic adaptation again with control module 28 ^-1* matrix element [A] * [BM]) is set the graphics processing unit 30 (step S308) of display device 3.According to one embodiment of the invention, graphics processing unit 30 comprises colour gamut respective modules 34 and Gamma modular converter 32.When gain matrix is adjusted in by the chromatic adaptation program, setting module 26 is with reference to the gain matrix of adjusting, can determine colour gamut corresponding relation and Gamma inverse transform relation, respectively colour gamut respective modules 34 and Gamma modular converter 32 are carried out parameter setting and adjustment by control module 28 again, make display device 3 according to the parameter that is set in the graphics processing unit 30, picture signal is shown on the panel 36.

Moreover, when graphics processing unit 30 be set finish after, to show that once more complete white picture signal is on the panel 36 of this display device 3, and whether the output colour temperature of measuring this complete white picture signal (for example: colour temperature 5000K reaches the target colour temperature, D50), or not with the color temperature difference of this target colour temperature less than predetermined scope, whether continue to adjust this display device 3 with decision.When if this color temperature difference is not less than this preset range, then can repeat above-mentioned chromatic adaptation program, continue to adjust the chromatic adaptation matrix A in the gain matrix, and again set graphics processing unit 30 according to adjusted gain matrix, reach the target colour temperature or less than this predetermined scope until the colour temperature of output image signal.

By above-mentioned example, when knowing that color correcting method provided by the present invention and colour correcting apparatus are in linear space, by carrying out the chromatic adaptation program, so that all images that display device is exported (being that RGB is under the situation of any GTG value) all meets color and colour temperature requirement.Thus, just can solve in the known technology, only merely adjust the yield value of RGB, cause to have complete white picture only and test, and the picture all the other GTGs under may be by the problem of testing by color in non-linear space (for example, the color space of RGB).

Only, the above, it only is the detailed description of specific embodiments of the invention and graphic, be not in order to restriction the present invention, all scopes of the present invention should be as the criterion with described claim scope, any those skilled in the art in the field of the invention, can think easily and variation Jian modify and all can be encompassed in the claim scope that described the present invention defines.

Claims (15)

1. A color correction method for a display device, suitable for adjusting the output color of the display device, the display device has an image processing unit to control the output color, the color correction method comprises the following steps: displaying at least one image signal on the panel of the display device; measuring the image signal to obtain a color matrix, wherein the color matrix is in a linear space; In the linear space, the color matrix and the gain matrix are operated to output an output matrix; adjusting the gain matrix such that the output matrix is substantially the same as the target matrix; and According to the gain matrix, the image processing unit is set to correct the output color of the display device. 2. The color correction method according to claim 1, further comprising the steps of: After setting the image processing unit, output the image signal repeatedly, and measure the output color temperature of the image signal; judging whether the color temperature difference between the output color temperature and the target color temperature is smaller than a predetermined range; and If the color temperature difference is not less than the predetermined range, the gain matrix is adjusted, and the image processing unit is set according to the adjusted gain matrix to correct the output color of the display device. 3. The color correction method according to claim 1, wherein the linear space is a CIE XYZ color space, and the color matrix and the gain matrix operation also include the following steps: Convert the color matrix to the IPT LMS color space with the conversion matrix, and generate the first color conversion matrix; operating the first color transformation matrix with a color adaptation matrix to generate a second color transformation matrix; and The second color transformation matrix is transformed back into the CIE XYZ color space with the inverse transformation matrix, and the output matrix is produced. 4. The color correction method according to claim 3, wherein the transformation matrix is a BradfordMatrix. 5. The color correction method according to claim 3, wherein adjusting the gain matrix is adjusting the LMS ratio of the chromatic adaptation matrix. 6. The color correction method according to claim 1, wherein measuring the image signal to obtain the color matrix further comprises the following steps: measuring the image signal to obtain the color display characteristics of the display device, wherein the color display characteristics include the color gamut and gray scale (Gamma) performance of the panel; and According to the color display characteristic, the color matrix is generated, wherein the color matrix corresponds to the chrominance value and the brightness value of the image signal. 7. The color correction method according to claim 1, wherein the image processing unit of the display device comprises a color gamut correspondence module and a Gamma conversion module. 8. The color correction method according to claim 1, wherein the image signal is an all-white frame. 9. A color correction device, suitable for adjusting the output color of a display device, the display device has an image processing unit for controlling the output color, the color correction device comprising: a colorimeter for measuring at least one image signal displayed by the display device; a display characteristic calculation module, configured to calculate the image signal measured by the colorimeter to generate a color matrix, wherein the color matrix is located in a linear space; A chromatic adaptation calculation module, configured to perform operations on the color matrix and the gain matrix in the linear space to output an output matrix; an adjustment unit, used to adjust the gain matrix so that the output matrix is substantially the same as the target matrix; and The setting module is used for setting the image processing unit to correct the output color of the display device according to the gain matrix. 10. The color correction device according to claim 9, wherein the color correction device further comprises a control module, the control module is used to drive a panel of the display device so that the image signal is displayed on the panel. 11. The color correction device according to claim 9, wherein the image signal comprises an all-white image, an all-red image, an all-green image, and an all-blue image, and the all-red image, the all-green image, and the all-grayscale The all blue image. 12. The color correction device according to claim 9, wherein the color matrix conforms to the CIE XYZ color space, and the color adaptation calculation module comprises: a chromatic adaptation matrix decision unit, configured to store the gain matrix, wherein the gain matrix includes a transformation matrix, a chromatic adaptation matrix and an inverse transformation matrix; and The color space conversion/calculation unit is coupled to the color adaptation matrix decision unit, and is used to convert the color matrix to the IPT LMS color space according to the conversion matrix to generate a first color conversion matrix, and convert the first color The conversion matrix is operated with the chromatic adaptation matrix to generate a second color conversion matrix, and then the second color conversion matrix is converted back to the CIE XYZ color space according to the inverse conversion matrix to generate the output matrix. 13. The color correction device according to claim 12, wherein the transformation matrix is a BradfordMatrix. 14. The color correction device according to claim 12, wherein the adjustment unit adjusts the LMS ratio of the color adaptation matrix. 15. The color correction device according to claim 9, wherein the image processing unit of the display device comprises a color gamut correspondence module and a Gamma conversion module.

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