WO2017080015A1 - 控制低灰阶白平衡的方法及装置 - Google Patents

控制低灰阶白平衡的方法及装置 Download PDF

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WO2017080015A1
WO2017080015A1 PCT/CN2015/097723 CN2015097723W WO2017080015A1 WO 2017080015 A1 WO2017080015 A1 WO 2017080015A1 CN 2015097723 W CN2015097723 W CN 2015097723W WO 2017080015 A1 WO2017080015 A1 WO 2017080015A1
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max
gray level
gray
color difference
threshold
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PCT/CN2015/097723
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English (en)
French (fr)
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陈黎暄
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深圳市华星光电技术有限公司
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Priority to US14/913,688 priority Critical patent/US9965989B2/en
Publication of WO2017080015A1 publication Critical patent/WO2017080015A1/zh

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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/2003—Display of colours
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/2007—Display of intermediate tones
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G09G3/3607—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/64—Circuits for processing colour signals
    • H04N9/73—Colour balance circuits, e.g. white balance circuits or colour temperature control
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0242—Compensation of deficiencies in the appearance of colours
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0666—Adjustment of display parameters for control of colour parameters, e.g. colour temperature

Definitions

  • the present invention relates to the field of image display technologies, and in particular, to a method and apparatus for controlling low gray scale white balance.
  • the white balance gray scale color performance will have a considerable degree of color shift difference.
  • Grayscale white balance adjustment must be performed on a pair of displays.
  • the gray scale white balance adjustment method of the prior art is to first display the white image of the pixels of the display in all gray levels, and then adjust the gain value (Gain) of the image intensity of the red, green and blue images to display the white image.
  • the chromaticity and brightness values are close to the chromaticity and brightness values of a target white, that is, the white image is adjusted within a certain range of color temperature and color derivation.
  • the debugging of low gray level is a difficulty.
  • the current white balance method has no good processing method. It is often after the calculation of the higher gray level, manually debugging the white balance of the low gray level, and designing the R/G/ with the subjective feeling of the human eye. B lookup table.
  • the above manual adjustment method increases the workload of the development designer, and there is a large error due to the subjective feelings between people.
  • the automatic method the formula is complicated and cumbersome, the calculation amount is large, and the calculated white balance, when the human eye is subjectively observed, the transition is not smooth in the low gray level.
  • the technical problem to be solved by the present invention is to provide a method and device for controlling low gray scale white balance, which can automatically adjust the white balance, and make the transition of the low gray scale smooth and natural when viewed by the human eye.
  • a technical solution adopted by the present invention is to provide a method for controlling a low gray scale white balance, where the low gray scale refers to a gray scale less than or equal to a gray scale threshold n max , the method includes: a tristimulus value of the obtained gray scale 0 and the gray scale threshold n max is calculated as a total color difference ⁇ E(n max ⁇ 0) between the gray scale 0 and the gray scale threshold n max ; according to the gray scale 0 And a total color difference ⁇ E(n max ⁇ 0) between the grayscale threshold n max , determining a color difference relationship between the gray scales from the gray scale 0 to the gray scale threshold n max , the color difference relationship Obtaining, by the human eye, that the gray scale 0 to the gray scale threshold n max is gradually changed smoothly; controlling white according to the color difference relationship between the gray scale 0 and the gray scale threshold n max Balanced; wherein the color difference relationship is ⁇ E, the ⁇ E
  • the tristimulus value obtained by measuring the gray scale 0 and the gray scale threshold n max is used to calculate a total color difference ⁇ E(n max ⁇ 0) between the gray scale 0 and the gray scale threshold n max step, comprising: measuring tristimulus values are 0 and the gray level value n max of the threshold gray level; by 0 and the gray scale value of the tristimulus value n max of the threshold gray level, the gray level is calculated and the 0 The total color difference ⁇ E(n max -0) between the grayscale thresholds n max .
  • said 0 and the gray scale by the gray level threshold value n max is tristimulus values, and calculating the gray level 0 to the gray level threshold between the total color difference ⁇ E n max (n max -0) of step, comprising: the gray level 0 and the gray level threshold value n max is tristimulus values and reference tristimulus values of the white point, and obtaining the gray level 0 to the gray level value n max of the threshold L, a , b values; 0 and the gray scale by the gray level threshold value n max of the L, a, b values to calculate the total color difference ⁇ E between the gray level and the gray level 0 threshold value n max (n max - 0).
  • the gray scale threshold n max is 30.
  • another technical solution adopted by the present invention is to provide a method for controlling low gray scale white balance, where the low gray scale refers to a gray scale less than or equal to a gray scale threshold n max , the method includes : obtained by measuring the gray scale value 0 and the gray level threshold tristimulus value n max and 0 in calculating the gray level of the total color difference ⁇ E between a gray level threshold value n max (n max -0); according to the a total color difference ⁇ E(n max ⁇ 0) between the gray scale 0 and the gray scale threshold n max , determining a color difference relationship between the gray scales from the gray scale 0 to the gray scale threshold n max , The color difference relationship is such that the human eye observes that the gray scale 0 to the gray scale threshold n max is gradually and smoothly changed; according to the color difference relationship between the gray scale 0 and the gray scale threshold n max among the gray scales , control white balance.
  • the color difference relationship is ⁇ E, and the ⁇ E is ⁇ E(n max ⁇ 0)/(n max ⁇ 0).
  • the color difference relationship is ⁇ E(m), and the ⁇ E(m) is f( ⁇ E(n max —0)/(n max —0)), wherein the f is such that the ⁇ E(m) A function that monotonically increases as the gray scale m increases, and the ⁇ E(m) refers to the color difference between the gray scale m and the gray scale m-1.
  • the tristimulus value obtained by measuring the gray scale 0 and the gray scale threshold n max is used to calculate a total color difference ⁇ E(n max ⁇ 0) between the gray scale 0 and the gray scale threshold n max step, comprising: measuring tristimulus values are 0 and the gray level value n max of the threshold gray level; by 0 and the gray scale value of the tristimulus value n max of the threshold gray level, the gray level is calculated and the 0 The total color difference ⁇ E(n max -0) between the grayscale thresholds n max .
  • said 0 and the gray scale by the gray level threshold value n max is tristimulus values, and calculating the gray level 0 to the gray level threshold between the total color difference ⁇ E n max (n max -0) of step, comprising: the gray level 0 and the gray level threshold value n max is tristimulus values and reference tristimulus values of the white point, and obtaining the gray level 0 to the gray level value n max of the threshold L, a , b values; 0 and the gray scale by the gray level threshold value n max of the L, a, b values to calculate the total color difference ⁇ E between the gray level and the gray level 0 threshold value n max (n max - 0).
  • the gray scale threshold n max is 30.
  • the low gray scale refers to a gray scale less than or equal to a gray scale threshold n max
  • the device includes : calculating module for gray scale obtained by measuring the tristimulus values 0 and the gray level threshold value n max and 0 in calculating the gray level of the gray scale the total color difference ⁇ E between the threshold value n max (n max -0 ); determining module for total color difference ⁇ E (n max -0) between 0 and the gray level of the gray level threshold value n max, is determined from the gray level 0 to the gray level of the threshold value n max a color difference relationship between the gray scales, the color difference relationship is such that the human eye observes that the gray scale 0 to the gray scale threshold n max is gradually and smoothly changed; and the control module is configured to use the gray scale 0 to The color difference relationship between each gray scale in the grayscale threshold n max is controlled to control
  • the color difference relationship is ⁇ E, and the ⁇ E is ⁇ E(n max ⁇ 0)/(n max ⁇ 0).
  • the color difference relationship is ⁇ E(m), and the ⁇ E(m) is f( ⁇ E(n max —0)/(n max —0)), wherein the f is such that the ⁇ E(m) A function that monotonically increases as the gray scale m increases, and the ⁇ E(m) refers to the color difference between the gray scale m and the gray scale m-1.
  • the calculation module comprises: a measurement unit for measuring respectively 0 grayscale and the tristimulus values of the gray level threshold value n max; calculation unit for said gray scale by the gray level and the threshold value 0 n max The tristimulus value calculates a total color difference ⁇ E(n max -0) between the gray scale 0 and the gray scale threshold n max .
  • the calculation unit includes: an obtaining subunit, configured to obtain the grayscale 0 and the ground by the tristimulus value of the grayscale 0 and the grayscale threshold nmax , and the tristimulus value of the reference whitepoint a L, a, b value of the grayscale threshold n max ; a calculation subunit, configured to calculate the grayscale 0 and the location by the L, a, and b values of the grayscale 0 and the grayscale threshold n max The total color difference ⁇ E(n max -0) between the gray scale thresholds n max is described.
  • the gray scale threshold n max is 30.
  • Advantageous effects of the present invention are: to be distinguished from the prior art, gray tristimulus values 0 and n max threshold gray level of the present invention obtained by measuring the total color difference ⁇ E between the calculated gray level threshold gray level 0 and n max (n max -0); the total color difference ⁇ E (n max -0) between the gray level and the threshold gray level 0 n max, the color difference is determined from the relationship between the gray level threshold value n max 0 level gray scale of each to The color difference relationship causes the human eye to observe that the gray scale 0 to the gray scale threshold n max is gradually changed smoothly; the white balance is controlled according to the color difference relationship between the gray scales 0 to the gray scale threshold n max .
  • the human eye Due to the color difference relationship between the gray scales, the human eye observes that the gray scale 0 to the gray scale threshold n max is gradually and smoothly changed, and then controls the white balance according to the color difference relationship. In this way, the white balance can be automatically adjusted, and When the human eye observes, the low gray level transition is smooth and natural.
  • FIG. 1 is a schematic diagram of a chromaticity curve after completion of debugging in the prior art
  • FIG. 2 is a schematic diagram of a brightness curve after debugging is completed in the prior art
  • FIG. 3 is a schematic diagram showing a smooth and continuous gray-scale transition after white balance, subjectively observing anomalies without color and brightness;
  • FIG. 4 is a flow chart of an embodiment of a method for controlling low gray scale white balance according to the present invention.
  • FIG. 5 is a flow chart of another embodiment of a method for controlling low gray scale white balance according to the present invention.
  • FIG. 6 is a flow chart of still another embodiment of a method for controlling low gray scale white balance according to the present invention.
  • FIG. 7 is a schematic structural view of an embodiment of an apparatus for controlling low gray scale white balance according to the present invention.
  • the image processing technology divides the display area on the liquid crystal panel into a plurality of pixels (Pixel), and each pixel includes sub-pixels of three primary colors such as red, green, and blue.
  • the color of all visible light can be generated by the combination of red, green and blue light. Therefore, by controlling the brightness of the red, green and blue sub-pixels, the color to be represented by one pixel can be constructed.
  • CIE 1931XYZ Color Space CIE 1931XYZ color space
  • CIE XYZ Color Space CIE 1931XYZ color space
  • Color space refers to the sensation of color on the human eye in an objective way, usually requiring tristimulus values. More precisely, first, define three primary colors, and then use the color overlay model to describe the colors. It should be noted that the three main colors are not necessarily true colors (that is, the colors cannot be really created). In the three-color additive color model, if the colors of the three primary colors of one color and the other are mixed to make the humans look the same, the components of the three primary colors are called the color. Tristimulus value.
  • the CIE 1931 color space usually gives the tristimulus value of the color and is represented by X, Y, and Z.
  • tristimulus values do not refer to human eyes for short, medium, and long waves (S, The reaction of M and L), but a set of values called X, Y and Z, roughly corresponding to red, green and blue (but note that the X, Y and Z values do not really look red, green And blue, but the parameters derived from red, green, and blue), and calculated using the CIE 1931 XYZ color matching function.
  • the complete plot of all visible colors is three-dimensional. But the concept of color can be divided into two parts: lightness and chromaticity. For example, white is a bright color, while gray is considered to be a less bright white. In other words, the shades of white and gray are the same, and the brightness is different.
  • the CIE XYZ color space is deliberately designed to measure the brightness or brightness of the color.
  • the chromaticity of the color is then specified by two derived parameters x and y, which are two of the three values normalized by a function of all three tristimulus values X, Y and Z:
  • the exported color space is specified by x, y, and Y. It is called the CIE xyY color space and is widely used in practice to specify colors.
  • the X and Z tristimulus values can be calculated from the chrominance values x and y and Y tristimulus values:
  • WB White Balance
  • Fig. 1 and Fig. 2 The chromaticity and brightness curves of the known debugging are shown in Fig. 1 and Fig. 2.
  • the abscissa is gray scale
  • the ordinate is x color coordinate value or y color coordinate value
  • the abscissa is gray scale.
  • the ordinate is the gamma value.
  • the existing method is easy in the process of calculating a low grayscale white balance before the (x, y) reaches 255 grayscale color target (x 0 , y 0 ) before calculating such as 20 gray scales, or before gamma rises to 2.2.
  • one of the most practical problems is that regardless of the form of the rising curve, the requirement of the low gray level is that its gray-scale transition is smooth and continuous, subjectively observed without color and brightness anomalies, as shown in Figure 3.
  • the invention solves the phenomenon that the transition of the low gray level is not smooth when the white balance is solved from the angle of the total color difference, specifically: the gray scale 0 and the gray scale threshold n max obtained by the measurement.
  • the tristimulus value calculates a total color difference ⁇ E(n max -0) between the gray scale 0 and the gray scale threshold n max ; according to the total color difference ⁇ E(n max -0) between the gray scale 0 and the gray scale threshold n max , Determining the color difference relationship between gray scales from gray scale 0 to gray scale threshold n max , the color difference relationship causes the human eye to observe that the gray scale 0 to gray scale threshold n max is gradually and smoothly changed; according to gray scale 0 to gray scale The color difference relationship between the gray levels in the threshold n max controls the white balance.
  • the human eye Due to the color difference relationship between the gray scales, the human eye observes that the gray scale 0 to the gray scale threshold n max is gradually and smoothly changed, and then controls the white balance according to the color difference relationship. In this way, the white balance can be automatically adjusted, and When the human eye observes, the low gray level transition is smooth and natural.
  • FIG. 4 is a flowchart of an embodiment of a method for controlling low gray scale white balance according to the present invention.
  • the low gray level refers to a gray level less than or equal to a gray level threshold n max , and the method includes:
  • Step S101 gray threshold gray level 0 and n max is obtained by measuring the tristimulus values calculated total color difference ⁇ E between the gray level and the threshold gray level 0 n max (n max -0).
  • (x 0 , y 0 ) is the color coordinate of the reference white point.
  • the grayscale threshold n max is 30.
  • Chromatic aberration refers to the numerical method of expressing the difference in color perception between two colors.
  • the step S102 The total color difference ⁇ E (n max -0) between the gray level and the threshold gray level 0 n max, is determined from the grayscale 0 to n max threshold gray level relationship between the respective color in the gray scale, color relationship such that The human eye observes that the gray scale 0 to the gray scale threshold n max is gradually and smoothly changed.
  • the color difference relationship between the gray scales refers to the variation law of the color difference between the gray scales.
  • the color difference relationship between the gray scales from the gray scale 0 to the gray scale threshold n max can be adjusted.
  • the grayscale changes from 0 to nmax it is obvious that the change is a smooth change, there is no very similar feeling, and there is no sudden, unnatural feeling. This color difference relationship can be determined based on existing experience.
  • the gray scales of each gray scale are gradually increased, and the ratio of the equal differences is determined according to actual conditions, such as: gray scales 1 to 20 are 1, 2, 3, 4, ..., 20, respectively: or gray scale 1 Up to 20 are 1, 3, 5, 7, 9, 11, 13, 15, ..., 39; or each gray scale is gradually increasing according to the gray scale, not the difference, but with the gray scale And the linearity increases, for example, the gray scales 1 to 9 are 1, 2, 4, 7, 11, 15, 21, 28, 36, respectively.
  • Step S103 Control the white balance according to the color difference relationship between the gray scales of the gray scale 0 to the gray scale threshold n max .
  • the white balance can be adjusted and controlled accordingly.
  • Tristimulus values and gray level threshold gray level 0 n max embodiment of the present invention is obtained by measuring the total color difference ⁇ E is calculated between 0 and grayscale gray threshold value n max (n max -0); according to the gray and gray 0
  • the total color difference ⁇ E(n max -0) between the order thresholds n max determines the color difference relationship between the gray scales from the gray scale 0 to the gray scale threshold n max , and the color difference relationship causes the human eye to observe the gray scale 0 to gray
  • the order threshold n max is gradually changed smoothly; the white balance is controlled according to the color difference relationship between the gray levels of the gray scale 0 to the gray scale threshold n max .
  • the white balance is controlled according to the color difference relationship, in this way, the white balance can be automatically adjusted, and When the human eye observes, the low gray level transition is smooth and natural.
  • the color difference relationship is ⁇ E, and ⁇ E is ⁇ E(n max -0) / (n max -0).
  • the color difference relationship is to equally divide the total color difference between the grayscale 0 and the grayscale threshold nmax , and for each intermediate grayscale m (0 ⁇ m ⁇ nmax ), it is adjacent to the adjacent
  • the color difference of the gray scales m-1 and m+1 is ⁇ E.
  • the chromatic aberration of each adjacent gray scale is arranged at equal intervals, and the chromatic aberration relationship of the present embodiment can be employed when it is not necessary to clearly highlight the details which are brighter and brighter.
  • the color difference relationship is ⁇ E(m), and ⁇ E(m) is f( ⁇ E(n max -0)/(n max -0)), where f is such that ⁇ E(m) monotonously increases with gray scale m
  • the incremental function, ⁇ E(m) refers to the color difference between grayscale m and grayscale m-1.
  • ⁇ E(m) is a function that monotonically increases as the gray level m increases.
  • the chromatic aberration of each adjacent gray level is arranged according to unequal spacing.
  • the actual ⁇ E(m) of the adjacent gray level will be larger.
  • step S101 may specifically include: sub-step S1011 and sub-step S1012.
  • Sub-step S1011 The tristimulus values of the grayscale 0 and the grayscale threshold nmax are measured, respectively.
  • Sub-step S1012 Calculate the total color difference ⁇ E(n max -0) between the gray level 0 and the gray level threshold n max by the tristimulus value of the gray level 0 and the gray level threshold n max .
  • sub-step S1012 includes: sub-step S10121 and sub-step S10122.
  • Sub-step S10121 0 by gray level and the threshold gray level n max tristimulus values and reference tristimulus values of white points, gray level 0 is obtained and the grayscale threshold value n max L, a, b values.
  • Sub-step S10122 0 by gray and gray level threshold value n max of the L, a, b values to calculate the total color difference ⁇ E between the gray level and the threshold gray level 0 n max (n max -0).
  • gray level and the threshold gray level 0 n max tristimulus values and reference tristimulus values of white points, gray level 0 is obtained and the grayscale threshold value n max L, a, b values. Then, the gray level and the threshold gray level 0 n max of L, a, b values to calculate the total color difference ⁇ E between the gray level and the threshold gray level 0 n max (n max -0).
  • X n , Y n and Z n are the tristimulus values of the reference white point in the CIE XYZ system. Under the D65 light source, its value is:
  • L*, a*, b* can be obtained from the tristimulus values X, Y, and Z under a certain gray level, and accordingly, L* (n max) of the gray scale n max can be obtained. ), a*(n max ), b*(n max ), and L*(0), a*(0), b*(0) of grayscale 0. Then calculate the formula based on the total color difference:
  • FIG. 7 is a schematic structural diagram of an apparatus for controlling low gray scale white balance according to the present invention.
  • the low gray level refers to a gray scale less than or equal to a grayscale threshold n max .
  • the device in this embodiment may perform the steps in the foregoing method. For details of related content, refer to the method part above, which will not be described in detail herein.
  • the device comprises: a calculation module 101, a determination module 102 and a control module 103.
  • Calculation module 101 gray tristimulus values 0 and n max threshold gray level is calculated by measuring the total color difference ⁇ E obtained between the gray level and the threshold gray level 0 n max (n max -0).
  • Module 102 for determining the total color difference ⁇ E (n max -0) between the gray level and the threshold gray level 0 n max is determined from the grayscale 0 to the grayscale color difference threshold value n max relationship between the respective gray scale, color The relationship causes the human eye to observe that the grayscale 0 to grayscale threshold nmax is gradually and smoothly varied.
  • the control module 103 is configured to control the white balance according to the color difference relationship between the gray scales of the gray scale 0 to the gray scale threshold n max .
  • Tristimulus values and gray level threshold gray level 0 n max embodiment of the present invention is obtained by measuring the total color difference ⁇ E is calculated between 0 and grayscale gray threshold value n max (n max -0); according to the gray and gray 0
  • the total color difference ⁇ E(n max -0) between the order thresholds n max determines the color difference relationship between the gray scales from the gray scale 0 to the gray scale threshold n max , and the color difference relationship causes the human eye to observe the gray scale 0 to gray
  • the order threshold n max is gradually changed smoothly; the white balance is controlled according to the color difference relationship between the gray levels of the gray scale 0 to the gray scale threshold n max .
  • the human eye Due to the color difference relationship between the gray scales, the human eye observes that the gray scale 0 to the gray scale threshold n max is gradually and smoothly changed, and then controls the white balance according to the color difference relationship. In this way, the white balance can be automatically adjusted, and When the human eye observes, the low gray level transition is smooth and natural.
  • the grayscale threshold n max is 30.
  • the color difference relationship is ⁇ E, and ⁇ E is ⁇ E(n max -0) / (n max -0).
  • the color difference relationship is ⁇ E(m), and ⁇ E(m) is f( ⁇ E(n max -0)/(n max -0)), where f is such that ⁇ E(m) monotonously increases with gray scale m
  • the incremental function, ⁇ E(m) refers to the color difference between grayscale m and grayscale m-1.
  • the calculation module 101 includes: a measurement unit and a calculation unit.
  • the measuring unit is configured to measure the tristimulus values of the grayscale 0 and the grayscale threshold nmax , respectively.
  • the calculation unit is configured to calculate a total color difference ⁇ E(n max ⁇ 0) between the gray level 0 and the gray level threshold n max by the tristimulus value of the gray level 0 and the gray level threshold n max .
  • the calculation unit includes: an acquisition subunit and a calculation subunit.
  • the calculation subunit is configured to calculate the total color difference ⁇ E(n max ⁇ 0) between the gray scale 0 and the gray scale threshold n max by the L, a, b values of the gray scale 0 and the gray scale threshold n max .

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Abstract

本发明公开了一种控制低灰阶白平衡的方法及装置，该方法包括：通过测量得到的灰阶0和灰阶阈值nmax的三刺激值计算灰阶0和灰阶阈值nmax之间的总色差ΔE(nmax-0)；根据灰阶0和灰阶阈值nmax之间的总色差ΔE(nmax-0)，确定从灰阶0到灰阶阈值nmax中各个灰阶之间的色差关系，色差关系使得人眼观察到灰阶0到灰阶阈值nmax是逐步平滑变化的；根据灰阶0到灰阶阈值nmax中各个灰阶之间的色差关系，控制白平衡。通过上述方式，本发明能够自动调节白平衡，且使得人眼观察时，低灰阶过渡平滑、自然。

Description

控制低灰阶白平衡的方法及装置 【技术领域】
本发明涉及图像显示技术领域，特别是涉及一种控制低灰阶白平衡的方法及装置。
【背景技术】
由于液晶面板的驱动与特性等因素，其白平衡灰阶色彩表现会有相当程度的色偏差异。为使显示器的色彩达到一定的正确性与一致性，因此，必须逐一对显示器进行灰阶白平衡(Grayscale white balance)的调整。
现有技术的灰阶白平衡的调整方法是先使显示器的像素在所有灰阶下显示白色影像，然后调整红、绿、蓝三色影像强度的增益值(Gain)，使其显示的白色影像的色度与亮度值接近于一目标白色的色度与明度值，也就是将白色影像调整在一定的色温(Color temperature)及色偏差(Color derivation)范围内。其中，低灰阶的调试是一个困难。对于低灰阶，现行的白平衡方法并无较好的处理方法，往往是在计算出较高灰阶以后，手动调试低灰阶的白平衡，以人眼之主观感受来设计R/G/B查找表。另外，也有通过算法实现自动调节低灰阶白平衡的。
但是，上述手动调节的方法，增加了开发设计人员的工作量，同时由于人与人之间主观感受的不同，存在较大的误差。自动的方法，公式复杂繁琐，计算量大，且计算出来的白平衡，人眼主观观察时，在低灰阶出现过渡不平滑的现象。
【发明内容】
本发明主要解决的技术问题是提供一种控制低灰阶白平衡的方法及装置，能够自动调节白平衡，且使得人眼观察时，低灰阶过渡平滑、自然。
为解决上述技术问题，本发明采用的一个技术方案是：提供控制低灰阶白平衡的方法，所述低灰阶是指小于等于灰阶阈值nmax的灰阶，所述方法包括：通过测量得到的灰阶0和所述灰阶阈值nmax的三刺激值计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)；根据所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)，确定从所述灰阶0到所述灰阶阈值nmax中各个灰阶之间的色差关系，所述色差关系使得人眼观察到所述灰阶0到所述灰阶阈值nmax 是逐步平滑变化的；根据所述灰阶0到所述灰阶阈值nmax中各个灰阶之间的色差关系，控制白平衡；其中，所述色差关系为ΔE，所述ΔE为ΔE(nmax-0)/(nmax-0)；或，其中，所述色差关系为ΔE(m)，所述ΔE(m)为f(ΔE(nmax-0)/(nmax-0))，其中，所述f是使得所述ΔE(m)随灰阶m增大而单调递增的函数，所述ΔE(m)是指灰阶m和灰阶m-1之间的色差。
其中，所述通过测量得到的灰阶0和所述灰阶阈值nmax的三刺激值计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)的步骤，包括：分别测量灰阶0和所述灰阶阈值nmax的三刺激值；通过所述灰阶0和所述灰阶阈值nmax的三刺激值，计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)。
其中，所述通过所述灰阶0和所述灰阶阈值nmax的三刺激值，计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)的步骤，包括：通过所述灰阶0和所述灰阶阈值nmax的三刺激值，以及参考白点的三刺激值，获得所述灰阶0和所述灰阶阈值nmax的L、a、b值；通过所述灰阶0和所述灰阶阈值nmax的L、a、b值，计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)。
其中，所述灰阶阈值nmax为30。
为解决上述技术问题，本发明采用的另一个技术方案是：提供一种控制低灰阶白平衡的方法，所述低灰阶是指小于等于灰阶阈值nmax的灰阶，所述方法包括：通过测量得到的灰阶0和所述灰阶阈值nmax的三刺激值计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)；根据所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)，确定从所述灰阶0到所述灰阶阈值nmax中各个灰阶之间的色差关系，所述色差关系使得人眼观察到所述灰阶0到所述灰阶阈值nmax是逐步平滑变化的；根据所述灰阶0到所述灰阶阈值nmax中各个灰阶之间的色差关系，控制白平衡。
其中，所述色差关系为ΔE，所述ΔE为ΔE(nmax-0)/(nmax-0)。
其中，所述色差关系为ΔE(m)，所述ΔE(m)为f(ΔE(nmax-0)/(nmax-0))，其中，所述f是使得所述ΔE(m)随灰阶m增大而单调递增的函数，所述ΔE(m)是指灰阶m和灰阶m-1之间的色差。
其中，所述通过测量得到的灰阶0和所述灰阶阈值nmax的三刺激值计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)的步骤，包括：分别测量灰阶0和所述灰阶阈值nmax的三刺激值；通过所述灰阶0和所述灰阶阈值nmax的三刺激值，计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)。
其中，所述通过所述灰阶0和所述灰阶阈值nmax的三刺激值，计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)的步骤，包括：通过所述灰阶0和所述灰阶阈值nmax的三刺激值，以及参考白点的三刺激值，获得所述灰阶0和所述灰阶阈值nmax的L、a、b值；通过所述灰阶0和所述灰阶阈值nmax的L、a、b值，计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)。
其中，所述灰阶阈值nmax为30。
为解决上述技术问题，本发明采用的又一个技术方案是：提供一种控制低灰阶白平衡的装置，所述低灰阶是指小于等于灰阶阈值nmax的灰阶，所述装置包括：计算模块，用于通过测量得到的灰阶0和所述灰阶阈值nmax的三刺激值计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)；确定模块，用于根据所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)，确定从所述灰阶0到所述灰阶阈值nmax中各个灰阶之间的色差关系，所述色差关系使得人眼观察到所述灰阶0到所述灰阶阈值nmax是逐步平滑变化的；控制模块，用于根据所述灰阶0到所述灰阶阈值nmax中各个灰阶之间的色差关系，控制白平衡。
其中，所述色差关系为ΔE，所述ΔE为ΔE(nmax-0)/(nmax-0)。
其中，所述色差关系为ΔE(m)，所述ΔE(m)为f(ΔE(nmax-0)/(nmax-0))，其中，所述f是使得所述ΔE(m)随灰阶m增大而单调递增的函数，所述ΔE(m)是指灰阶m和灰阶m-1之间的色差。
其中，所述计算模块包括：测量单元，用于分别测量灰阶0和所述灰阶阈值nmax的三刺激值；计算单元，用于通过所述灰阶0和所述灰阶阈值nmax的三刺激值，计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)。
其中，所述计算单元包括：获得子单元，用于通过所述灰阶0和所述灰阶阈值nmax的三刺激值，以及参考白点的三刺激值，获得所述灰阶0和所述灰阶阈值nmax的L、a、b值；计算子单元，用于通过所述灰阶0和所述灰阶阈值nmax的L、a、b值，计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)。
其中，所述灰阶阈值nmax为30。
本发明的有益效果是：区别于现有技术的情况，本发明通过测量得到的灰阶0和灰阶阈值nmax的三刺激值计算灰阶0和灰阶阈值nmax之间的总色差ΔE(nmax-0)；根据灰阶0和灰阶阈值nmax之间的总色差ΔE(nmax-0)，确定从灰阶0到灰阶阈值nmax中各个灰阶之间的色差关系，色差关系使得人眼观察到灰阶0到灰阶阈值nmax是逐步平滑变化的；根据灰阶0到灰阶阈值nmax中各个灰阶之 间的色差关系，控制白平衡。由于各个灰阶之间的色差关系使得人眼观察到灰阶0到灰阶阈值nmax是逐步平滑变化的，然后根据该色差关系控制白平衡，通过这种方式，能够自动调节白平衡，且使得人眼观察时，低灰阶过渡平滑、自然。
【附图说明】
图1是现有技术中调试完成后的色度曲线示意图；
图2是现有技术中调试完成后的亮度曲线示意图；
图3是白平衡之后灰阶过渡平滑连续，主观观察无颜色和亮度的异常的示意图；
图4是本发明控制低灰阶白平衡的方法一实施方式的流程图；
图5是本发明控制低灰阶白平衡的方法另一实施方式的流程图；
图6是本发明控制低灰阶白平衡的方法又一实施方式的流程图；
图7是本发明控制低灰阶白平衡的装置一实施方式的结构示意图。
【具体实施方式】
在详细介绍本发明之前，首先说明一下与本发明相关的技术内容。
目前，图像处理技术是将液晶面板上的显示区域划分为许多的像素(Pixel)，每个像素上包括红、绿、蓝等三原色的子像素。所有可见光的颜色均可由红、绿、蓝三色光线混合产生，因此通过控制红、绿、蓝子像素的明暗，即可建构出一个像素所要表现的色彩。
为了更适当地描述色彩，国际照明委员会(International Commission on Illumination，简称CIE)提出了CIE1931XYZ色彩空间(CIE XYZ Color Space)。色彩空间指的是用一种客观的方式叙述颜色在人眼上的感觉，通常需要三色刺激值。更精确地说，首先，先定义三种主要颜色(primary color)，再利用颜色叠加模型，即可叙述各种颜色。需要注意的是，三种主要颜色未必是真正的颜色(也就是该种颜色无法真的被创造出来)。在三色加色法模型中，如果某一种颜色和另一种混合了不同分量的三种原色的颜色，均使人类看上去是相同的话，把这三种原色的分量称作该颜色的三色刺激值。CIE 1931色彩空间通常会给出颜色的三色刺激值，并以X、Y和Z来表示。
在CIE XYZ色彩空间中，三色刺激值并不是指人类眼睛对短、中和长波(S、 M和L)的反应，而是一组称为X、Y和Z的值，约略对应于红色、绿色和蓝色(但要留意X、Y和Z值并不是真的看起来是红、绿和蓝色，而是从红色、绿色和蓝色导出来的参数)，并使用CIE 1931 XYZ颜色匹配函数来计算。
因为人类眼睛有响应不同波长范围的三种类型的颜色传感器，所有可视颜色的完整绘图是三维的。但是颜色的概念可以分为两部分：明度和色度。例如，白色是明亮的颜色，而灰色被认为是不太亮的白色。换句话说，白色和灰色的色度是一样的，而明度不同。
CIE XYZ色彩空间故意设计得Y参数是颜色的明度或亮度的测量。颜色的色度接着通过两个导出参数x和y来指定，它们是所有三个三色刺激值X、Y和Z的函数所规范化的三个值中的两个：
Figure PCTCN2015097723-appb-000001
Figure PCTCN2015097723-appb-000002
Figure PCTCN2015097723-appb-000003
导出的色彩空间用x，y，Y来指定，它叫做CIE xyY色彩空间并在实践中广泛用于指定颜色。
X和Z三色刺激值可以从色度值x和y与Y三色刺激值计算回来：
Figure PCTCN2015097723-appb-000004
Figure PCTCN2015097723-appb-000005
白平衡(White Balance，简称WB)是一种去除非正常颜色的过程。在各种不同的色温下，目标物的色彩会发生变化。其中，白色物体变化的最为明显。为了尽可能减少外来光线对目标颜色造成的影响，在不同的色温条件下，都能还原出被摄目标本来的色彩，需要进行色彩校正，以达成正确的色彩平衡。
由于液晶显示面板低灰阶的显示特性，以及测量与计算的误差，在低灰阶自动计算白平衡往往是困难的。很重要的原因在于，低灰阶的亮度特性很难满足gamma＝2.2的要求。
已知调试完成的色度和亮度曲线如图1和图2所示，图1中横坐标为灰阶，纵坐标为x色坐标值或y色坐标值；图2中横坐标为灰阶，纵坐标为gamma值。从图中可以看到，亮度无法在初始阶段即达到需要的gamma＝2.2的效果，需要 从0灰阶上升到约20灰阶后才能保持平稳的gamma＝2.2的曲线；其色度也需要从0灰阶的(x，y)上升到约20灰阶左右才能与白色的(x，y)保持一致。
在计算诸如20灰阶以前，或gamma上升到2.2以前，(x，y)达到255灰阶颜色目标(x0，y0)以前的低灰阶白平衡的过程中，现有的方法很容易产生由于目标值与实际值偏离太远而导致的问题。例如：一个最实际的问题是不论上升曲线是何种形式，低灰阶的要求是其灰阶过渡平滑连续，主观观察无颜色和亮度的异常，如图3所示。
现有技术中，不管是手动调节还是自动调节，均是以目标亮度、参考白点为标准进行调节的。本发明在调节低灰阶的白平衡时，是从总色差的角度解决白平衡时低灰阶出现过渡不平滑的现象，具体来说是：通过测量得到的灰阶0和灰阶阈值nmax的三刺激值计算灰阶0和灰阶阈值nmax之间的总色差ΔE(nmax-0)；根据灰阶0和灰阶阈值nmax之间的总色差ΔE(nmax-0)，确定从灰阶0到灰阶阈值nmax中各个灰阶之间的色差关系，色差关系使得人眼观察到灰阶0到灰阶阈值nmax是逐步平滑变化的；根据灰阶0到灰阶阈值nmax中各个灰阶之间的色差关系，控制白平衡。由于各个灰阶之间的色差关系使得人眼观察到灰阶0到灰阶阈值nmax是逐步平滑变化的，然后根据该色差关系控制白平衡，通过这种方式，能够自动调节白平衡，且使得人眼观察时，低灰阶过渡平滑、自然。
下面结合附图和实施方式对本发明进行详细说明。
参阅图4，图4是本发明控制低灰阶白平衡的方法一实施方式的流程图，低灰阶是指小于等于灰阶阈值nmax的灰阶，该方法包括：
步骤S101：通过测量得到的灰阶0和灰阶阈值nmax的三刺激值计算灰阶0和灰阶阈值nmax之间的总色差ΔE(nmax-0)。
灰阶阈值nmax是指其颜色和亮度恰能满足gamma＝2.2与(x，y)＝(x0，y0)的要求，同时灰阶nmax-1依然处于亮度曲线的上升段中，其中，(x0，y0)是参考白点的色坐标。
其中，灰阶阈值nmax为30。
现有技术中，三刺激值的测量方法有很多。例如：重量纵坐标法、选择纵坐标法等等。
色差是指用数值的方法表示两种颜色给人色彩感觉上的差别。
已知灰阶0和灰阶阈值nmax的三刺激值后，即可根据总色差的计算公式计 算出灰阶0和灰阶阈值nmax之间的总色差ΔE(nmax-0)。在不同的系统中，总色差具体的计算公式略有不同。
例如：以CIE1976系统为例，
明度差：ΔL*＝L* 2-L* 1，
色度差：Δa*＝a* 2-a* 1，Δb*＝b* 2-b* 1，
总色差：
Figure PCTCN2015097723-appb-000006
另外，还有CIE1994系统、CIE2000系统等等，总色差具体的计算公式在此不再详细说明。
步骤S102：根据灰阶0和灰阶阈值nmax之间的总色差ΔE(nmax-0)，确定从灰阶0到灰阶阈值nmax中各个灰阶之间的色差关系，色差关系使得人眼观察到灰阶0到灰阶阈值nmax是逐步平滑变化的。
各个灰阶之间的色差关系是指各个灰阶之间的色差的变化规律。
在已知灰阶0和灰阶阈值nmax之间的总色差ΔE(nmax-0)的情况下，可以通过调节从灰阶0到灰阶阈值nmax中各个灰阶之间的色差关系，使得灰阶从0变化到nmax的时候，让人眼观察到该变化是平滑变化的，没有非常一样的感觉，也没有变化很突然，不自然的感觉。这个色差关系是可以根据已有的经验来确定的。例如：各个灰阶等差逐步递增，等差的比例根据实际情况确定，如：灰阶1到20分别是1、2、3、4、......、20，或者：灰阶1到20分别是1、3、5、7、9、11、13、15、......、39；或者各个灰阶根据灰阶不是等差逐步递增，而是随着灰阶的上升，而线性增加，如：灰阶1到9分别是1、2、4、7、11、15、21、28、36。
步骤S103：根据灰阶0到灰阶阈值nmax中各个灰阶之间的色差关系，控制白平衡。
在各个灰阶之间的色差关系确定后，据此即可调节并控制白平衡。
本发明实施方式通过测量得到的灰阶0和灰阶阈值nmax的三刺激值计算灰阶0和灰阶阈值nmax之间的总色差ΔE(nmax-0)；根据灰阶0和灰阶阈值nmax之间的总色差ΔE(nmax-0)，确定从灰阶0到灰阶阈值nmax中各个灰阶之间的色差关系，色差关系使得人眼观察到灰阶0到灰阶阈值nmax是逐步平滑变化的；根据灰阶0到灰阶阈值nmax中各个灰阶之间的色差关系，控制白平衡。由于各个灰阶之间的色差关系使得人眼观察到灰阶0到灰阶阈值nmax是逐步平滑变化的， 然后根据该色差关系控制白平衡，通过这种方式，能够自动调节白平衡，且使得人眼观察时，低灰阶过渡平滑、自然。
其中，色差关系为ΔE，ΔE为ΔE(nmax-0)/(nmax-0)。
也就是说，色差关系是将灰阶0和灰阶阈值nmax之间的总色差进行等分的，对于每个中间灰阶m(0＜m＜nmax)来说，其与相邻的灰阶m-1、m+1的色差均是ΔE。这种方式每个相邻灰阶的色差是按照等间距排列的，当不需要明显突出由亮变得更加亮的细节时，可以采用本实施方式的色差关系。
其中，色差关系为ΔE(m)，ΔE(m)为f(ΔE(nmax-0)/(nmax-0))，其中，f是使得ΔE(m)随灰阶m增大而单调递增的函数，ΔE(m)是指灰阶m和灰阶m-1之间的色差。
以CIE1976系统为例，对于灰阶m和m-1，存在如下关系：
Figure PCTCN2015097723-appb-000007
ΔE(m)为随灰阶m增大而单调递增的函数。
在这种方式中，每个相邻灰阶的色差是按照不等间距排列，对于越高的灰阶，根据人眼的反应，其实际与相邻灰阶的ΔE(m)会更大一些，越是到后面变亮的灰阶，变化越大，当需要明显突出由亮变得更加亮的细节时，可以采用本实施方式的色差关系。
其中，参见图5，步骤S101具体可以包括：子步骤S1011和子步骤S1012
子步骤S1011：分别测量灰阶0和灰阶阈值nmax的三刺激值。
子步骤S1012：通过灰阶0和所述灰阶阈值nmax的三刺激值，计算灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)。
进一步地，参见图6，子步骤S1012包括：子步骤S10121和子步骤S10122。
子步骤S10121：通过灰阶0和灰阶阈值nmax的三刺激值，以及参考白点的三刺激值，获得灰阶0和灰阶阈值nmax的L、a、b值。
子步骤S10122：通过灰阶0和灰阶阈值nmax的L、a、b值，计算灰阶0和灰阶阈值nmax之间的总色差ΔE(nmax-0)。
在不同的CIE Lab系统中，由于计算公式的不同，具体的计算过程不相同。
下面以CIE1976为例，说明子步骤S10122的计算过程。
首先，通过灰阶0和灰阶阈值nmax的三刺激值，以及参考白点的三刺激值，获得灰阶0和灰阶阈值nmax的L、a、b值。然后，通过灰阶0和灰阶阈值nmax 的L、a、b值，计算灰阶0和灰阶阈值nmax之间的总色差ΔE(nmax-0)。
L*＝116f(Y/Yn)-16
a*＝500[f(X/Xn)-f(Y/Yn)]
b*＝200[f(Y/Yn)-f(Z/Zn)]
其中，
Figure PCTCN2015097723-appb-000008
其中，Xn、Yn以及Zn为CIE XYZ系统中参考白点的三刺激值。在D65光源下，其值为：
Xn＝0.95047，Yn＝1.00000，Zn＝1.08883
于是，根据某一个色度空间，可以从某一灰阶下的三刺激值X、Y、Z得到L*、a*、b*，据此，可得灰阶nmax的L*(nmax)、a*(nmax)、b*(nmax)与灰阶0的L*(0)、a*(0)、b*(0)。于是根据总色差计算公式：
Figure PCTCN2015097723-appb-000009
可得总色差ΔE(nmax-0)。
参见图7，图7是本发明控制低灰阶白平衡的装置一实施方式的结构示意图，低灰阶是指小于等于灰阶阈值nmax的灰阶。本实施方式的装置可以执行上述方法中的步骤，相关内容的详细说明请参见上述方法部分，在此不再详细叙述。
该装置包括：计算模块101、确定模块102以及控制模块103。
计算模块101用于通过测量得到的灰阶0和灰阶阈值nmax的三刺激值计算灰阶0和灰阶阈值nmax之间的总色差ΔE(nmax-0)。
确定模块102用于根据灰阶0和灰阶阈值nmax之间的总色差ΔE(nmax-0)，确定从灰阶0到灰阶阈值nmax中各个灰阶之间的色差关系，色差关系使得人眼观察到灰阶0到灰阶阈值nmax是逐步平滑变化的。
控制模块103用于根据灰阶0到灰阶阈值nmax中各个灰阶之间的色差关系，控制白平衡。
本发明实施方式通过测量得到的灰阶0和灰阶阈值nmax的三刺激值计算灰阶0和灰阶阈值nmax之间的总色差ΔE(nmax-0)；根据灰阶0和灰阶阈值nmax之间的总色差ΔE(nmax-0)，确定从灰阶0到灰阶阈值nmax中各个灰阶之间的色差关系，色差关系使得人眼观察到灰阶0到灰阶阈值nmax是逐步平滑变化的；根 据灰阶0到灰阶阈值nmax中各个灰阶之间的色差关系，控制白平衡。由于各个灰阶之间的色差关系使得人眼观察到灰阶0到灰阶阈值nmax是逐步平滑变化的，然后根据该色差关系控制白平衡，通过这种方式，能够自动调节白平衡，且使得人眼观察时，低灰阶过渡平滑、自然。
其中，灰阶阈值nmax为30。
其中，色差关系为ΔE，ΔE为ΔE(nmax-0)/(nmax-0)。
其中，色差关系为ΔE(m)，ΔE(m)为f(ΔE(nmax-0)/(nmax-0))，其中，f是使得ΔE(m)随灰阶m增大而单调递增的函数，ΔE(m)是指灰阶m和灰阶m-1之间的色差。
其中，计算模块101包括：测量单元和计算单元。
测量单元用于分别测量灰阶0和所述灰阶阈值nmax的三刺激值。
计算单元用于通过所述灰阶0和所述灰阶阈值nmax的三刺激值，计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)。
其中，计算单元包括：获得子单元和计算子单元。
获得子单元用于通过灰阶0和灰阶阈值nmax的三刺激值，以及参考白点的三刺激值，获得灰阶0和灰阶阈值nmax的L、a、b值。
计算子单元用于通过灰阶0和灰阶阈值nmax的L、a、b值，计算灰阶0和灰阶阈值nmax之间的总色差ΔE(nmax-0)。
以上所述仅为本发明的实施方式，并非因此限制本发明的专利范围，凡是利用本发明说明书及附图内容所作的等效结构或等效流程变换，或直接或间接运用在其他相关的技术领域，均同理包括在本发明的专利保护范围内。

Claims (16)

  1. 一种控制低灰阶白平衡的方法，其中，所述低灰阶是指小于等于灰阶阈值nmax的灰阶，所述方法包括：
    通过测量得到的灰阶0和所述灰阶阈值nmax的三刺激值计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)；
    根据所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)，确定从所述灰阶0到所述灰阶阈值nmax中各个灰阶之间的色差关系，所述色差关系使得人眼观察到所述灰阶0到所述灰阶阈值nmax是逐步平滑变化的；
    根据所述灰阶0到所述灰阶阈值nmax中各个灰阶之间的色差关系，控制白平衡；
    其中，所述色差关系为ΔE，所述ΔE为ΔE(nmax-0)/(nmax-0)；或，
    其中，所述色差关系为ΔE(m)，所述ΔE(m)为f(ΔE(nmax-0)/(nmax-0))，其中，所述f是使得所述ΔE(m)随灰阶m增大而单调递增的函数，所述ΔE(m)是指灰阶m和灰阶m-1之间的色差。
  2. 根据权利要求1所述的方法，其中，所述通过测量得到的灰阶0和所述灰阶阈值nmax的三刺激值计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)的步骤，包括：
    分别测量灰阶0和所述灰阶阈值nmax的三刺激值；
    通过所述灰阶0和所述灰阶阈值nmax的三刺激值，计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)。
  3. 根据权利要求2所述的方法，其中，所述通过所述灰阶0和所述灰阶阈值nmax的三刺激值，计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)的步骤，包括：
    通过所述灰阶0和所述灰阶阈值nmax的三刺激值，以及参考白点的三刺激值，获得所述灰阶0和所述灰阶阈值nmax的L、a、b值；
    通过所述灰阶0和所述灰阶阈值nmax的L、a、b值，计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)。
  4. 根据权利要求1所述的方法，其中，所述灰阶阈值nmax为30。
  5. 一种控制低灰阶白平衡的方法，其中，所述低灰阶是指小于等于灰阶阈值nmax的灰阶，所述方法包括：
    通过测量得到的灰阶0和所述灰阶阈值nmax的三刺激值计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)；
    根据所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)，确定从所述灰阶0到所述灰阶阈值nmax中各个灰阶之间的色差关系，所述色差关系使得人眼观察到所述灰阶0到所述灰阶阈值nmax是逐步平滑变化的；
    根据所述灰阶0到所述灰阶阈值nmax中各个灰阶之间的色差关系，控制白平衡。
  6. 根据权利要求5所述的方法，其中，所述色差关系为ΔE，所述ΔE为ΔE(nmax-0)/(nmax-0)。
  7. 根据权利要求5所述的方法，其中，所述色差关系为ΔE(m)，所述ΔE(m)为f(ΔE(nmax-0)/(nmax-0))，其中，所述f是使得所述ΔE(m)随灰阶m增大而单调递增的函数，所述ΔE(m)是指灰阶m和灰阶m-1之间的色差。
  8. 根据权利要求5所述的方法，其中，所述通过测量得到的灰阶0和所述灰阶阈值nmax的三刺激值计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)的步骤，包括：
    分别测量灰阶0和所述灰阶阈值nmax的三刺激值；
    通过所述灰阶0和所述灰阶阈值nmax的三刺激值，计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)。
  9. 根据权利要求8所述的方法，其中，所述通过所述灰阶0和所述灰阶阈值nmax的三刺激值，计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)的步骤，包括：
    通过所述灰阶0和所述灰阶阈值nmax的三刺激值，以及参考白点的三刺激值，获得所述灰阶0和所述灰阶阈值nmax的L、a、b值；
    通过所述灰阶0和所述灰阶阈值nmax的L、a、b值，计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)。
  10. 根据权利要求5-9任一项所述的方法，其中，所述灰阶阈值nmax为30。
  11. 一种控制低灰阶白平衡的装置，其中，所述低灰阶是指小于等于灰阶阈值nmax的灰阶，所述装置包括：
    计算模块，用于通过测量得到的灰阶0和所述灰阶阈值nmax的三刺激值计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)；
    确定模块，用于根据所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE (nmax-0)，确定从所述灰阶0到所述灰阶阈值nmax中各个灰阶之间的色差关系，所述色差关系使得人眼观察到所述灰阶0到所述灰阶阈值nmax是逐步平滑变化的；
    控制模块，用于根据所述灰阶0到所述灰阶阈值nmax中各个灰阶之间的色差关系，控制白平衡。
  12. 根据权利要求11所述的装置，其中，所述色差关系为ΔE，所述ΔE为ΔE(nmax-0)/(nmax-0)。
  13. 根据权利要求11所述的装置，其中，所述色差关系为ΔE(m)，所述ΔE(m)为f(ΔE(nmax-0)/(nmax-0))，其中，所述f是使得所述ΔE(m)随灰阶m增大而单调递增的函数，所述ΔE(m)是指灰阶m和灰阶m-1之间的色差。
  14. 根据权利要求11所述的装置，其中，所述计算模块包括：
    测量单元，用于分别测量灰阶0和所述灰阶阈值nmax的三刺激值；
    计算单元，用于通过所述灰阶0和所述灰阶阈值nmax的三刺激值，计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)。
  15. 根据权利要求14所述的装置，其中，所述计算单元包括：
    获得子单元，用于通过所述灰阶0和所述灰阶阈值nmax的三刺激值，以及参考白点的三刺激值，获得所述灰阶0和所述灰阶阈值nmax的L、a、b值；
    计算子单元，用于通过所述灰阶0和所述灰阶阈值nmax的L、a、b值，计算所述灰阶0和所述灰阶阈值nmax之间的总色差ΔE(nmax-0)。
  16. 根据权利要求11-15任一项所述的装置，其中，所述灰阶阈值nmax为30。
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