JP2006217377A - Display calibration method and program for display calibration - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a user to perform proper color calibration without knowing a type of a color display device. <P>SOLUTION: Relational expressions in a plurality of calibration methods are prepared as relational expressions giving relations between input signals inputted to a display device being a calibration object and output colors displayed on the display device, and data sets 1, 2, and 3 for the coefficient determination of respective relational expressions and a data set 5 for color reproduction precision determination are prepared, and calibration is performed in order from a calibration method using a relational expression having the smallest number of data sets for coefficient determination out of the plurality of calibration methods, and calibration is terminated in response to reach the prescribed precision of color reproduction precision (step S10). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a display calibration method and display calibration program for calibrating the display color of a display, and in particular, a display calibration method and a display calibration program that can be appropriately calibrated even if a general user calibrates without knowing the type of display. About.

  A self-luminous display such as a color CRT (cathode ray tube) is an additive display that reproduces a color by mixing primary colors of R (red), G (green), and B (blue). Additivity holds. Therefore, the color reproduction characteristics can be predicted with a relatively simple model. For example, the relationship between the input signal and the output color of the color CRT is often formulated by the following equations (1) and (2).

  However, it is known that a liquid crystal type color display that has been widely used in recent years may not be modeled by the above formulas 1 and 2, even though it is an additive display. When such a display is calibrated by obtaining the relationship between the input signal and the output color, a three-dimensional lookup table (LUT) system that handles the input / output relationship as a black box is often used. However, in this three-dimensional LUT method, it is necessary to measure a very large number of colors, and the work becomes complicated.

  In other words, when calibration is performed using a model formulated by Equations 1 and 2, there are advantages in that the amount of measurement data is small and the calculation process is simple and fast, but there are large errors depending on the type of display. Has the disadvantages. In addition, the LUT method has the advantage of being able to calibrate with any type of display with high accuracy. However, a large amount of color measurement is required, and the calculation process is complicated. It has the disadvantage that it takes a long time to complete.

  As a conventional technique related to color CRT calibration, there is the following Patent Document 1.

JP 2000-333217 A

  If a color display is calibrated by an expert, calibration using the above equations 1 and 2 or calibration using a three-dimensional LUT method can be appropriately selected according to the type of color display.

  However, in recent years, general users who have color displays have frequently calibrated themselves at home or office, and it is not possible to select an appropriate calibration method. Even if it is only necessary, the calibration using the 3D LUT method is performed over a long period of time. There is a problem of having to work with a bad color display.

  Furthermore, in recent years, various types of self-luminous type color displays have been developed such as color displays using plasma displays and EL elements, surface electric field displays, in addition to color CRT and liquid crystal color displays. It has become difficult for a general user to determine an optimal calibration method for calibrating a color display used by the general user.

  An object of the present invention is to provide a display calibration method and a display calibration program capable of performing appropriate color calibration without the user knowing the type of color display.

  The display calibration method of the present invention prepares a relational expression for each of a plurality of calibration methods as a relational expression for giving a relation between an input signal inputted to a display to be calibrated and an output color displayed on the display, and each relational expression. The coefficient determination data set and the color reproduction accuracy determination data set are prepared, and among the calibration methods using each relational expression, a calibration method based on a relational expression that achieves a predetermined color reproduction accuracy is employed. To do.

  The display calibration method of the present invention performs the calibration work in order from the calibration technique using the relational expression having a small number of coefficient determination data sets among the plurality of calibration techniques, and the calibration work is performed when the color reproduction accuracy reaches a predetermined accuracy. It is characterized by terminating.

  The display calibration method of the present invention is a calibration work for data that overlaps with a coefficient determination data set used in the calibration work of the calibration technique performed so far among the coefficient determination data sets used when performing a calibration work with a certain calibration technique. Is characterized by using the result of calibration work already performed.

  The display calibration method of the present invention is characterized in that a calibration operation is performed by selecting one of a plurality of types of color reproduction accuracy determination data sets prepared.

  The display calibration program of the present invention is a display calibration program executed by a computer, and implements the display calibration method described above.

  According to the present invention, even if the user does not know the type of display, color calibration is executed by an appropriate calibration method, and color display with high color reproduction accuracy is possible. Further, when performing color calibration of the display, it is possible to perform display calibration with the least number of colorimetry and data amount as much as possible in order to achieve a desired color reproduction accuracy.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a flowchart showing a processing procedure of a display calibration program according to an embodiment of the present invention. In the present embodiment, three types of data sets 1 and 2 for level I, level II, and level III are used as coefficient determination data sets used when calibration is performed by a display calibration program executed by a computer. , 3 are prepared.

  2 is a diagram illustrating a list of coefficient determination data sets 1 for level I, FIG. 3 is a diagram illustrating a list of coefficient determination data sets 2 for level II, and FIG. It is a figure which illustrates the list of the coefficient determination data set 3 for level III.

  In this embodiment, the level I display calibration method is first executed. When the level I display calibration method cannot be properly calibrated, the process proceeds to the level II display calibration method. When calibration is not possible, it proceeds to the level III display calibration method.

  As a level I display calibration method, a method that requires the least amount of measurement data, is simple in calculation processing, and can be performed at the highest speed is adopted. For example, the display calibration method using Equations 1 and 2 described above is used.

  The last level III display calibration technique requires a large amount of color measurement and complicates the calculation process, but employs a method that enables high-precision calibration of any type of display. For example, the above-described three-dimensional LUT type display calibration method is assumed to be level III.

  The intermediate level II display calibration method employs a method that requires intermediate measurement data amount and calculation processing between level I and level III. For example, a method in which the relationship of Equation 1 with respect to Equation 1 and Equation 2 described above is replaced with a one-dimensional lookup table.

  In this embodiment, three levels of calibration methods of level I, II, and III are prepared. However, the number of calibration methods is not limited to three, but only two levels or four or more levels may be provided. Needless to say.

  The display calibration program of the present embodiment further includes a color reproduction accuracy determination data set 5. FIG. 4 is a diagram showing a list of data sets of a Macbeth chart (which includes all the colors in the color space) as an example of the color reproduction accuracy determination data set 5. In addition, as a data set for judging color reproduction accuracy, data set 6 including skin color and data set 7 including sky blue and plant color are prepared so that the skin color can be calibrated so that it can be clearly displayed on the display. It may be possible to calibrate so that sky blue and vegetation are clearly displayed on the display.

  When the display calibration program is started, first, a selection screen for selecting a color reproduction accuracy determination data set is displayed to the user. On this selection screen, the user selects a color reproduction accuracy determination data set (step S1). ). For example, a Macbeth chart is selected. Alternatively, a data set including skin color is selected.

  Next, the coefficient determination data set 1 for level I is automatically selected (step S2), whereby the color corresponding to the coefficient determination data set 1 is displayed on the display (step S3). A colorimetric sensor is attached to the display surface, and the tristimulus values XYZ of display colors are measured by the colorimetric sensor (step S4).

  The computer automatically takes in the colorimetric data from the colorimetric sensor, calculates the coefficient values of the formulas 1 and 2 by arithmetic processing (step S5), and determines the coefficient values (step S6). Next, the computer performs an inverse operation using Equations 1 and 2 for which coefficient values are determined in Step S6, and obtains a display signal for displaying the color of the color reproduction accuracy determination data set by calculation. The signal is displayed on the display (step S7).

  The displayed color is measured again by the colorimetric sensor (step S8), and the difference between the XYZ value set in the color reproduction accuracy determination data set and the XYZ value measured in step S8 is obtained (step S8). S9). When calculating the color difference, it is more preferable to calculate the color difference after converting from the XYZ color system to a uniform color space such as L * a * b *.

  Next, it is determined whether or not the average value of the color difference values is within a color reproduction accuracy range assumed in advance (step S10). If the determination result is affirmative (Yes), that is, if the color reproduction accuracy is within a predetermined range, the execution of the calibration program is terminated, and the coefficient values determined in step S6 are used as display calibration data.

  If the color reproduction accuracy is outside the target range, that is, if the determination result in step S10 is negative (No), the process returns to step S2, and this time, the level II coefficient determination data set 2 is stored. Selected.

  Then, the color is displayed on the display according to the coefficient determination data set 2 for level II (step S3), and the tristimulus values XYZ of the displayed color are measured by the colorimetric sensor (step S4). Next, a one-dimensional lookup table for each of RGB and each coefficient value of Formula 2 are determined from the measurement results of the colorimetric sensor (steps S5 and S6).

  Next, a display signal for displaying the color of the color reproduction accuracy determination data set 5 is obtained by calculation by inverse calculation of the level II equation and displayed on the display (step S7), and the displayed color is measured. Color (step S8), obtain a difference between the XYZ value set in the color reproduction accuracy determination data set and the XYZ value measured in step S8 (step S9), and the average value of the difference values is assumed in advance It is determined whether it is within the range of reproduction accuracy (step S10).

  As a result of the determination in step S10, if the color difference value is within the predetermined range of the color reproduction accuracy, the execution of the display calibration program is terminated, and the lookup table value and coefficient value obtained in step S6 are used as the display calibration data. To do.

  If the result of determination in step S10 is that the color reproduction accuracy is outside the target range, that is, if the determination result is negative (No), the process returns to step S2, and this time the coefficient determination data set for level III 3 is automatically selected, and thereafter, in the same manner as described above, the color is displayed on the display according to the data set 3, the tristimulus values XYZ of the display color are measured, and all the measured data are used as a three-dimensional lookup table. By using this, display calibration data is obtained and the display calibration program is terminated.

  In the display calibration program of the present embodiment described above, the level I display calibration method is first executed, and when the level I display calibration method fails to perform proper calibration, the process proceeds to the level II display calibration method. When proper calibration is not possible with this display calibration method, the process proceeds to the level III display calibration method, but there is also a demand for a shorter time required for calibration.

  Therefore, in the present embodiment, the time required for measuring data overlapping at levels I, II, and III is reduced. That is, among the data sets used in level II, there are data sets that have already been measured by level I calibration (data sets that overlap with FIG. 2 are indicated by hatching in the list of FIG. 3. In the list of FIG. 4, the data set overlapping with FIG. 3 is indicated by hatching.) For the data set once measured, the previous measurement result is used.

  As described above, according to the display calibration program of the present embodiment, an appropriate calibration method according to the type of display is executed regardless of the type of display. Even in this case, a color display with excellent color reproducibility can be obtained. Further, when a plurality of different types of displays are calibrated, it is possible to shorten the time required for total calibration.

  In the above-described embodiment, the user selects one of the color reproduction accuracy determination data sets in step S1 of FIG. 1. However, each of the color reproduction accuracy determination data sets is automatically selected in order to perform Macbeth. It is also possible to automatically obtain calibration data corresponding to a chart, skin color calibration data, plant color calibration data, and the like. In this way, when the image to be displayed on the display is a human image, the user can select flesh color calibration data. When displaying a landscape image of a forest or the like on the display, the calibration data for plant color is used. The user can select it.

  In the present invention, it is possible to appropriately calibrate the display regardless of the type of display, and therefore, it is useful as a display calibration program for a general user to calibrate the display by himself / herself.

It is a flowchart which shows the process sequence of the program for a display calibration which concerns on one Embodiment of this invention. It is a figure which illustrates the list of the coefficient determination data sets for level I used with the display calibration program shown in FIG. It is a figure which illustrates the list of the coefficient determination data sets for level II used with the display calibration program shown in FIG. It is a figure which illustrates the list of the coefficient determination data sets for level III used with the display calibration program shown in FIG. It is a figure which illustrates the list of the data set for color reproduction accuracy determination used with the display calibration program shown in FIG.

Explanation of symbols

1 Data set for coefficient determination for level I 2 Data set for coefficient determination for level II 3 Data set for coefficient determination for level III 5 Data set for color reproduction accuracy judgment

Claims (5)

  A relational expression for each of a plurality of calibration methods is prepared as a relational expression for giving a relation between an input signal input to a display to be calibrated and an output color displayed on the display, and a coefficient determination data set and a color for each relational expression are prepared. A display calibration method characterized by preparing a data set for determining reproduction accuracy and employing a calibration method based on a relational expression that achieves a predetermined accuracy in color reproduction accuracy among calibration methods using each relational expression.   A calibration operation is sequentially performed from a calibration method using a relational expression with a small number of coefficient determination data sets among the plurality of calibration methods, and the calibration operation is terminated when the color reproduction accuracy has achieved a predetermined accuracy. The display calibration method according to claim 1.   Of calibration data set used when performing calibration work with a certain calibration method, the calibration work result for the data that overlaps with the coefficient determination data set used in the calibration work of the calibration method performed so far The display calibration method according to claim 1, wherein the display calibration method is used.   4. The display calibration method according to claim 1, wherein a calibration operation is performed by selecting one of a plurality of types of color reproduction accuracy determination data sets prepared.   5. A display calibration program executed by a computer, which realizes the display calibration method according to claim 1.

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