JP2010203825A - Method for measuring spectral distribution of monitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for measuring a spectral distribution of a monitor, capable of enhancing the resolution of measurement, without changing apertures of a spectrometric device. <P>SOLUTION: The measuring method for the spectral distribution of the monitor by the use of the spectrometric device includes: a first measuring step of displaying on the monitor a color patch having a size smaller than the measuring region of the spectrometric device, and measuring the color patch by using the spectrometric device, while displaying regions other than the color patch of the monitor as black; and a correction step of acquiring a corrected spectral distribution by multiplying the spectral distribution acquired by the first measuring step by a correction coefficient having a value of one or above. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for measuring a spectral distribution of a monitor performed in monitor color management or the like.

  In recent years, various devices have been developed by grasping the characteristics of input devices such as scanners and digital cameras, display devices such as monitors, output devices such as printers and printing, describing the characteristics in files, and using the characteristics files. A technique called color management that matches the colors of colors is common.

  This color management is generally performed in accordance with an ICC standard proposed by an organization called ICC (International Color Consortium). In the ICC standard, a characteristic file is called a profile.

  In particular, in monitor color management, a monitor profile is generally created after the monitor is calibrated to predetermined characteristics. In addition, there are a method in which only color monitor calibration is performed and a profile is created based on predetermined characteristics, and a method in which only a profile is created without performing calibration.

  In order to perform color management of the monitor, it is necessary to measure three elements: chromaticity of a white point, luminance, gradation reproduction characteristics, and chromaticity of RGB primary colors. In this measurement, a color patch having a size larger than the area to be measured by the measuring instrument is arranged.

  The measuring instruments used at this time are roughly classified into stimulus value direct reading type and spectroscopic type.

  The stimulus value direct-reading type directly measures the stimulus value through an optical filter approximated to the spectral response of the color matching function, and the spectroscopic type performs spectroscopy using a diffraction grating and measures the radiation amount for each wavelength. Then, the stimulus value is calculated using the color matching function data.

  Although the stimulus value direct reading type is relatively inexpensive, it is difficult to design an optical filter having the same spectral response as that of the color matching function, and the measurement accuracy is generally inferior to that of the spectral type. Various techniques for improving measurement accuracy have been proposed. However, since the spectral distribution cannot be measured with the stimulus value direct reading type, there is a limit to improving accuracy. Therefore, a spectroscopic type is used for highly accurate measurement.

  In the spectroscopic measuring instrument, an area to be measured is determined by an aperture provided in the measuring instrument, and light that has passed through the aperture is split by a diffraction grating and applied to a sensor. As the aperture angle increases, the amount of incident light increases, and even if the integration time is short, it is less susceptible to noise, but the angle at which light enters the diffraction grating varies and the resolution decreases. Further, as the aperture angle is smaller, a sufficient integration time is required to reduce the influence of noise, but the resolution is improved. For this reason, an appropriate aperture is usually incorporated depending on the intended use of the measuring instrument.

JP 2007-322203 A

  On the other hand, there are CRT monitors and liquid crystal monitors as monitors for color management. 10 to 12 show spectral distributions of a CRT monitor and a liquid crystal monitor measured with a spectroscopic colorimeter having an aperture with an aperture angle of 0.5 degrees.

  FIG. 10 shows the spectral distribution of a CRT monitor, FIG. 11 shows the spectral distribution of a liquid crystal monitor using a cold cathode tube, and FIG. 12 shows the spectral distribution of a liquid crystal monitor using LEDs. In either case, the horizontal axis represents the wavelength λ (nm) and the vertical axis represents the spectral radiance.

  As shown in FIGS. 10 to 12, the CRT monitor and the liquid crystal monitor have a large change in the amount of radiation depending on the wavelength. Therefore, accurate measurement cannot be performed with a measuring instrument with low resolution.

  Therefore, when measuring the spectral distribution of the monitor, it is desirable to measure using a spectrophotometer having as high a resolution as possible, in other words, a small aperture angle.

  However, the aperture provided in the spectrometer is generally not exchangeable, and even if it can be exchanged, there is a problem that it takes cost and labor for exchange.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for measuring the spectral distribution of a monitor that improves the resolution of measurement without changing the aperture of the spectrometer.

  In order to solve the above problem, the spectral distribution measuring method of the monitor according to claim 1 is a measuring method of the spectral distribution of the monitor using the spectroscopic measuring device, and the measuring region (for example, aperture diameter) of the spectroscopic measuring device. A first measurement step of displaying a color patch of a smaller size (for example, a white patch) on the monitor, setting the area other than the color patch of the monitor as black, and measuring the color patch using the spectroscopic instrument; And a correction step of obtaining a corrected spectral distribution by multiplying the spectral distribution obtained in the first measuring step by a correction coefficient having a value of 1 or more. .

  According to this invention, a color patch having a size smaller than the measurement region (aperture diameter) of the spectrometer is displayed on the monitor and measured, and the obtained spectral distribution is enlarged and corrected by multiplying by one or more correction coefficients. Thus, it is possible to realize a spectral distribution measurement method for a monitor that can improve measurement resolution without changing the aperture of the spectrometer.

  In order to solve the above problem, the spectral distribution measurement method of the monitor according to claim 2 is the spectral distribution measurement method of the monitor according to claim 1, wherein the first measurement step is other than the color patch of the monitor. This is a spectral distribution measurement method for a monitor, characterized in that the region is displayed in black by setting the region to a light emitting state with the lowest luminance.

  According to the present invention, the spectral distribution measurement of the monitor can be performed accurately and precisely.

  In order to solve the above problem, the spectral distribution measurement method of the monitor according to claim 3 is the spectral distribution measurement method of the monitor according to claim 1, wherein the first measurement step is other than the color patch of the monitor. By covering the area with a shielding object having a light transmittance of 20% or less from the monitor side to the spectrometer side and having a light reflectance of 20% or less on the spectrometer side, This is a spectral distribution measurement method for a monitor, characterized in that the area is black.

  According to the present invention, the spectral distribution measurement of the monitor can be performed accurately and precisely.

In order to solve the above problem, a spectral distribution measurement method for a monitor according to claim 4 is the spectral distribution measurement method for a monitor according to any one of claims 1 to 3, wherein the measurement by the spectrometer is performed. display color patches over sized area on the monitor, the second measuring step of measuring the displayed color patches using the spectrophotometer, the spectral distribution P ₂ obtained by the second measuring step ( λ) and a step of calculating a correction coefficient k by the following equation (1) based on the spectral distribution P ₁ (λ) obtained by the first measurement step, the correction step comprising: Spectral distribution of a monitor characterized in that a corrected spectral distribution P (λ) is obtained by the following equation (2) based on the spectral distribution P ₁ (λ) obtained by one measurement step and the calculated correction coefficient k. This is a measurement method.

  According to the present invention, accurate brightness (luminance) is acquired by measuring a color patch (for example, a white patch for luminance correction) having a size larger than the measurement region of the spectrophotometer, and correction is performed based on this. Since the coefficient k is acquired, the luminance can be corrected more accurately.

In order to solve the above problem, a spectral distribution measurement method for a monitor according to claim 5 is the spectral distribution measurement method for a monitor according to any one of claims 1 to 4, wherein a black patch is attached to the monitor. Displaying and measuring the luminance value (Y _Black ) of the displayed black patch using the spectrophotometer, and an error (ΔY _Error ) of a predetermined luminance value in the measured luminance value of the black patch ) To calculate a threshold value, display color patches of different sizes on the monitor, measure the respective luminance values, and select the size of the color patches having a luminance value larger than the calculated threshold value. Measuring a spectral distribution of a monitor, comprising: determining a color patch having a minimum value as a color patch to be displayed on the monitor in the first measurement step It is the law.

  According to the present invention, the spectral distribution of the monitor can be measured with higher accuracy.

  According to the present invention, a color patch having a size smaller than the measurement region (aperture diameter) of the spectrometer is displayed on the monitor and measured, and the obtained spectral distribution is enlarged and corrected by multiplying by one or more correction coefficients. Thus, it is possible to realize a spectral distribution measurement method for a monitor that can improve measurement resolution without changing the aperture of the spectrometer.

It is explanatory drawing which shows the outline of a structure of the spectral distribution measurement system S which concerns on this embodiment, and a use condition. FIG. 2 is a schematic configuration diagram of a spectrometer 2. (A) It is explanatory drawing which shows the display position of the white patch in the monitor M, and the position of the measurement area | region of the spectrometer 2. FIG. (B) is explanatory drawing of the aperture diameter R which is a measurement area | region. It is a graph of the diameter of a white patch and the measured luminance value Y. It is an example of a spectral distribution P _{1 (λ)} of the white patches. It is an example of the white patch for brightness correction. It is an example of the spectral distribution P ₂ (λ) of the white patch for luminance correction. It is an example of correction | amendment spectral distribution P ((lambda)). This is a spectral distribution of the monitor M measured by a spectrophotometer having an aperture with an aperture angle θ = 0.5 degrees. It is a spectral distribution of a CRT monitor. It is a spectral distribution of a liquid crystal monitor using a cold cathode tube. It is a spectral distribution of the liquid crystal monitor using LED.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.

<1. Configuration and Function of Spectral Distribution Measurement System S>
First, the spectral distribution measurement system S according to the present embodiment will be conceptually described with reference to FIG.

  FIG. 1 is an explanatory diagram showing a schematic configuration and a usage state of a spectral distribution measurement system S according to the present embodiment.

  As shown in the figure, the spectral distribution measurement system S includes a display device 1 including a monitor M, which is a color monitor to be color management, and a white patch (an example of a color patch) displayed on the monitor M. A spectrophotometer 2 that performs colorimetry, and a computer 3 that connects the display device 1 and the spectrophotometer 2 and performs processing for calculating a correction coefficient k, which will be described later, and the like.

  The display device 1 is a monitor M that performs color reproduction by additive color mixing of the three primary colors R (red), G (green), and B (blue), such as a color CRT, a color liquid crystal display device, and a color plasma display display device. A display device. In the present embodiment, the display device 1 including the monitor M using a cold cathode tube backlight liquid crystal is used.

  The spectroscopic measuring instrument 2 uses a non-contact type or a contact type spectroscopic measuring instrument constituted by an aperture, a diffraction grating, a sensor and the like.

  FIG. 2 shows a schematic configuration diagram of the spectrometer 2. Light incident from the aperture of the spectrometer 2 is dispersed by a diffraction grating, and radiance (spectral radiance) is acquired and measured for each wavelength by a sensor. In the present embodiment, a measuring instrument having an aperture angle θ of 2 degrees is used.

  The computer 3 is connected to the display device 1 and the spectroscopic measuring instrument 2 so as to be able to perform data communication with each other by a serial method, a USB method, IEEE1394, or other appropriate method. The measurement result of the white patch displayed on M is received from the spectrometer 2, and a correction coefficient k used in luminance correction described later is calculated, and processing such as luminance correction using the correction coefficient k is performed.

  As for the white patch displayed on the monitor M of the display device 1, for example, the computer 3 transmits white patch data having an RGB gradation value of 255 (R = G = B = 255) to the display device 1, and the display device 1 And a white patch is displayed on the monitor M. If the main body of the display device 1 has a monitor display adjustment function, the computer 3 transmits an RGB adjustment instruction signal such that the RGB gradation value 255 (R = G = B = 255) to the display device 1. The display device 1 may be configured to display the white patch on the monitor M based on the received RGB adjustment instruction signal.

  FIG. 3A is an explanatory diagram showing the display position of the white patch on the monitor M and the position of the measurement region of the spectrometer 2.

  The display position of the white patch is preferably at the center of the measurement region of the spectrometer 2 (illustrated by a dotted line circle in the figure). Accordingly, the white patch may be visually arranged so as to be positioned at the center of the measurement region of the spectrometer 2 or the white patch may be arranged in the vertical direction (monitor y direction) of the monitor M and the left and right of the monitor M. When the radiance is measured by the spectrometer 2 while moving in the direction (x direction) and measured while moving the white patch in the up and down direction, each position in the up and down direction where the measured value becomes almost zero and does not change Is determined as the position in the y direction, and when measuring while moving the white patch in the left and right direction, the intermediate position between the left and right positions where the measurement value becomes almost zero and does not change is determined in the x direction. It is also possible to determine the position of the white patch and arrange the white patch at the determined position.

  Also, the shape of the white patch is preferably circular because the measurement region (aperture diameter) of the spectrometer 2 is generally circular.

  FIG. 3B is an explanatory diagram of an aperture diameter R that is a measurement region, and the aperture diameter R is determined by the aperture angle θ of the spectrometer 2 and the distance L between the monitor M and the spectrometer 2. . For example, when the aperture angle θ is 2 degrees and the distance L between the monitor M and the spectrometer 2 is 50 cm, the aperture diameter R is about 17 mm.

  A circular white patch having a diameter of about 5 mm smaller than the measurement region (aperture diameter R) of the spectrometer 2 is displayed on the monitor M and measured by the spectrometer 2. Note that the size of the white patch is preferably as small as possible than the size of the measurement region of the spectrometer 2.

  In order to prevent reflection of room lighting or the like on the monitor M, the measurement of the white patch (and the white patch for luminance correction described later) by the spectrometer 2 is preferably performed in a dark room.

<2. Size determination of white patch>
Next, a method for determining the size of the white patch according to the present embodiment will be described in detail.

  First, the display device 1 displays a black patch on the monitor M. For example, by receiving black patch data having an RGB gradation value of 0 (R = G = B = 0) output from the computer 3, the black patch is displayed on the monitor M based on the black patch data.

Next, the spectrophotometer 2 measures the luminance value Y _Black of the black patch, and the computer 3 acquires data of the luminance value Y _Black measured from the spectrophotometer 2.

Then, the computer 3 calculates the error [Delta] Y _Error of the luminance values of spectrometer 2 is added to the luminance value _{Y Black} threshold _{(Y Black} + ΔY _Error). The luminance value error ΔY _Error is determined in advance depending on the performance of the spectrometer 2 and the pixel size of the monitor M, and is stored in advance in a storage unit (not shown) of the computer 3.

  Subsequently, the display device 1 displays white patches having different sizes on the monitor M, and the spectrophotometer 2 measures the luminance value Y for each white patch. The white patches may be displayed in order on the monitor M and the luminance value Y of each white patch may be measured in order by the spectrophotometer 2 or a plurality of white patches may be displayed side by side on the monitor M. Then, while moving the spectrometer 2 (or moving the monitor M), the measurement area of the spectrometer 2 is configured to measure each luminance value Y in order while combining each white patch at the center of the measurement area. Also good. At this time, only the white patch to be measured is placed in the measurement region of the spectrometer 2.

  Then, the computer 3 acquires data of the luminance value Y of each white patch from the spectroscopic measuring device 2.

  FIG. 4 shows a graph of the diameter of the white patch and the measured luminance value Y.

  As shown in the figure, the luminance value Y increases as the diameter of the white patch increases.

The computer 3 compares the brightness value Y of each white patch with a threshold value (Y _Black + ΔY _Error ), and selects the white patch having the smallest size (diameter) among the white patches having the brightness value Y greater than the threshold value. The white patch to be measured is determined.

<3. Spectral distribution measurement of white patch>
Next, the spectral distribution is measured by the spectrometer 2 for the determined white patch to be measured.

  The display device 1 receives the white patch data of the determined white patch to be measured output from the computer 3 and displays the white patch on the monitor M based on the white patch data.

  Note that a portion (area) other than the white patch of the monitor M is configured to be black.

  For example, by setting the portion (area) other than the white patch of the monitor M of the display device 1 to the light emitting state with the lowest luminance (pixel value R = G = B = 0), the portion other than the white patch is displayed in black. Or a portion (area) other than the white patch of the monitor M of the display device 1 on the paper whose light transmittance from the monitor M side to the spectrometer 2 side is a predetermined value (for example, 20%) or less, A portion other than the white patch is configured to be black by covering with a shield such as a cloth or a plate.

  Further, as described above, the measurement of the white patch by the spectrophotometer 2 is preferably performed in a dark room. However, when the portion other than the white patch is made black by covering it with the shield, It is more preferable to use a shield having a light reflectance of at least a predetermined value (for example, 20%) or less on the spectrometer 2 side.

  Then, the spectral distribution of the white patch is measured by the spectrometer 2, and the computer 3 acquires the spectral distribution data measured from the spectrometer 2.

It shows an example of a measured spectral distribution P _{1 (λ)} in FIG.

FIG. 5 shows the spectral distribution P ₁ (λ) of the white patch having the wavelength λ (nm) on the horizontal axis and the spectral radiance P ₁ on the vertical axis.

  Since the white patch having a size smaller than the measurement area of the spectrometer 2 is measured, the exact brightness (luminance) of the monitor M cannot be measured. Accordingly, a white patch (hereinafter referred to as a brightness correction white patch) having a size larger than the measurement region of the spectrometer 2 is measured to perform brightness correction.

<4. Brightness correction>
First, the display device 1 receives the brightness correction white patch data of the determined brightness correction white patch output from the computer 3, and based on the brightness correction white patch data, the brightness correction white patch data is received. A white patch is displayed on the monitor M.

  FIG. 6 shows an example of a white patch for luminance correction.

  As shown in FIG. 6, the brightness correction white patch has a size larger than the measurement region of the spectrometer 2 (shown by a dotted circle in the figure), and the brightness correction white patch is measured by the spectrometer 2. The computer 3 acquires spectral distribution data measured from the spectrometer 2.

It shows an example of a measured spectral distribution P _{2 (λ)} in FIG.

FIG. 7 shows the spectral distribution P ₂ (λ) of the white patch for luminance correction having the wavelength λ (nm) on the horizontal axis and the spectral radiance P ₂ on the vertical axis.

The spectral distribution P ₂ (λ) of the white patch for luminance correction has a low resolution, but the luminance (brightness) is accurate.

Computer 3, the correction coefficient spectral distribution P ₁ as a white patch and _(lambda) (Fig. 5), the spectral distribution P ₂ of the white patches luminance correction _(lambda), based on (Figure 7), the following equation (1) k is calculated. In equation (1), y￣ (λ) represents a color matching function in the XYZ color system of CIE1931. Note that “y た” indicates a place indicating a horizontal bar (bar) on the letter y for convenience.

As can be seen from FIGS. 5 and 7, since the spectral radiance P ₂ of the white patches luminance correction is the spectral radiance P ₁ or more white patches, the correction coefficient calculated based on the equation (1) k is a value of 1 or more.

Then, to obtain the spectral distribution P ₁ as a white patch _(lambda), the correction spectral distribution P by based on the calculated correction coefficient k the following equation (2) (lambda).

  FIG. 8 shows an example of the corrected spectral distribution P (λ) after correction.

FIG. 8 shows the corrected spectral distribution P (λ) of the white patch having the wavelength λ (nm) on the horizontal axis and the spectral radiance P on the vertical axis. The brightness (brightness) is enlarged and corrected as compared to the spectral distribution P ₁ (λ) (FIG. 5) before correction.

  For comparison, spectral distributions obtained by measuring with other spectroscopic instruments under the same measurement conditions (the same room (for example, the same illumination light conditions), the same monitor M, the same white patch, etc.) are shown in FIG. Shown in

  FIG. 9 is a spectral distribution of the monitor M measured by a spectrophotometer having an aperture with an aperture angle θ = 0.5 degrees.

  Spectral distribution of the monitor M by the spectrometer 2 having an aperture with an aperture angle θ = 2 degrees (FIG. 8) and the spectral distribution of the monitor M by a spectrometer having an aperture with an aperture angle θ = 0.5 degrees (FIG. 9). As shown in FIG. 5, according to the spectral distribution measurement according to the present embodiment, the aperture angle is small even in the spectral distribution of the monitor M by the spectrometer 2 having an aperture with a large aperture angle (θ = 2 degrees). The measurement resolution could be improved to the same extent as when a spectrophotometer having an aperture of (θ = 0.5 degrees) was used.

As described above, according to the spectral distribution measurement method according to the present embodiment, the spectral distribution P ₁ (λ) obtained by measuring the white patch having a size smaller than the measurement region of the spectrometer 2 is represented by the luminance. By performing enlargement correction by correction, a spectral distribution P with high resolution can be obtained, and the spectral distribution measurement method of the monitor M with high measurement resolution can be realized without changing the aperture of the spectrometer 2.

  Further, by measuring the brightness correction white patch having a size larger than the measurement region of the spectrophotometer 2, the correct brightness (luminance) is acquired, and the correction coefficient k is acquired based on this, so that the correction coefficient k is more accurate. The brightness can be corrected.

Also, when measuring the spectral distribution P _{1 (λ)} by displaying white patch on the monitor M is for displaying a region other than white patches in the pixel value R = G = B = 0 for black, more precisely In addition, the spectral distribution of the monitor M can be strictly measured.

Further, among the white patches having a luminance value Y larger than the threshold value obtained by adding the luminance value Y _Black of the black patch displayed on the monitor M and the error ΔY _{Error of the} luminance value measured by the spectrophotometer 2. Since the smallest white patch is determined as the white patch to be measured, the spectral distribution of the monitor M can be measured with higher accuracy.

  In the present embodiment, the computer 3 receives measurement results such as spectral distribution data and luminance value Y data from the spectrometer 2. However, the operator of the computer 3 spectroscopically measures the measurement results obtained by the spectrometer 2. The result display unit of the device 2 is confirmed, the input device (keyboard or the like) provided in the computer 3 is operated to input the measurement result into the computer 3, and the correction coefficient k is calculated based on the data acquired by the computer 3. You may comprise so that it may perform.

  In this embodiment, the white patch is displayed on the monitor M, but other color patches may be used. For example, the present invention can also be applied when obtaining the spectral distribution of the RGB color patch.

S Spectral distribution measurement system 1 Display device M Monitor
2 Spectrometer 3 Computer

Claims (5)

A method for measuring a spectral distribution of a monitor using a spectroscopic instrument,
A first measurement step of displaying a color patch having a size smaller than a measurement area of the spectrometer on the monitor, and setting the area other than the color patch of the monitor to black, and measuring the color patch using the spectrometer When,
A correction step of obtaining a corrected spectral distribution by multiplying the spectral distribution obtained by the first measurement step by a correction coefficient having a value of 1 or more;
A spectral distribution measurement method for a monitor, comprising: The method of measuring spectral distribution of a monitor according to claim 1,
The method of measuring a spectral distribution of a monitor, wherein the first measurement step displays the area in black by setting an area other than the color patch of the monitor to a light emitting state with the lowest luminance. The method of measuring spectral distribution of a monitor according to claim 1,
In the first measurement step, an area other than the color patch of the monitor is
By covering the area with a shielding object having a light transmittance of 20% or less from the monitor side to the spectrometer side and having a light reflectance of 20% or less on the spectrometer side, the region is black. A method for measuring spectral distribution of a monitor. In the spectral distribution measurement method of the monitor according to any one of claims 1 to 3,
A second measurement step of displaying a color patch having a size equal to or larger than a measurement region of the spectrometer on the monitor and measuring the displayed color patch using the spectrometer;
Spectral and distribution P _{2 (lambda)} obtained by the second measuring step, and calculates the correction coefficient k by equation (1) below on the basis of the spectral distribution P ₁ obtained by the first measuring step _(lambda) A process, and
The correction step is to obtain a corrected spectral distribution P (λ) by the following equation (2) based on the spectral distribution P ₁ (λ) obtained by the first measurement step and the calculated correction coefficient k. Spectral distribution measurement method of monitor characterized.
Specified how to adjust the patch size.
The spectral distribution measurement method for a monitor according to any one of claims 1 to 4,
Displaying a black patch on the monitor, and measuring the luminance value of the displayed black patch using the spectrometer,
A step of calculating a threshold value by adding an error of a predetermined luminance value to the luminance value of the measured black patch;
The color patches having different sizes are displayed on the monitor, and the respective luminance values are measured. Among the color patches having luminance values larger than the calculated threshold value, the color patch having the smallest size is selected as the first measurement. Determining a color patch to be displayed on the monitor in the process;
A spectral distribution measurement method for a monitor, comprising: