JPH07203478A - Automatic correction device for white spot - Google Patents

Abstract

PURPOSE:To obtain the white spot automatic correction device by which a white spot on a color monitor is automatically corrected in response to an environment light. CONSTITUTION:An environmental light measurement means 0 provides an output of a signal corresponding to the intensity of each color component of the environmental light at a location where a color monitor 2 is placed, and a white spot measurement means 1 provides an output of a signal corresponding to the intensity of each color component of a white spot on the color monitor 2. An arithmetic operation means 3 calculates the difference of the signals and its difference signal is fed to a correction means 4. Then the correction means 4 corrects the balance of each drive voltage for R, G, B on the color monitor 2 based on the difference signal and data fed from a signal generating means 5 are fed to the color 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white point automatic correction device suitable for a color monitor.

[0002]

2. Description of the Related Art Three primary color signals (R (red), G (green),
There is a color monitor that reproduces a natural color image by controlling the amount of B (blue) and the mixing ratio thereof. As such a color monitor, for example, a color CRT that reproduces a natural color image by emitting light of R, G, and B phosphors, a color liquid crystal display using a backlight system, and the like are known. Especially color C
From the viewpoint of image quality, RT is expected to be applied to soft proof and color DTP in the future. In the color monitor used for these purposes, the correspondence between the reproduced color and the color perceived by the evaluator must always be constant. In addition, the color reproduced by the color monitor and the color output from the printer need to look the same. In such a case, the adjustment is performed with the white point on the color monitor as a reference. The white point is obtained by fully emitting R, G, and B to perform additive color mixing.

In a color monitor, even if the three primary color signals for driving each phosphor are constant, if the emission intensity of the phosphor is not constant, the color of the image reproduced on the monitor is constant. Does not mean Even if the primary color signal and the output signal are constant, the evaluator's visual system undergoes chromatic adaptation due to the influence of the ambient light of the place where the monitor is placed. When the evaluator's visual system is completely adapted to the ambient light, a color having a chromaticity value substantially the same as the chromaticity value (hue and saturation) in the ambient light is perceived as white. For this reason, there is a case where a color different from the color that should be originally perceived is perceived, for example, a white color signal is not perceived as white on the monitor.
Therefore, it is necessary for the visual system of the evaluator to perceive the white point (or reference white) of the monitor as white by adjusting the white point of the monitor according to the color of the ambient light.

Conventionally, in order to control the white point of the color monitor according to the ambient light as described above, the following device has been used. (A) When the operator sets several kinds of environments in which the monitor is installed in advance, the chromaticity value of the color perceived as white by the evaluator under the environment is stored as data for each environment. I'll do it. When the evaluator selects the most suitable data according to the environment used, the driving voltage of the color phosphor for displaying the white point is set based on the data (chromaticity value). (B) In the chromaticity coordinate system, the correspondence between each point and the drive voltage on each of the R, G, and B monitors for obtaining the chromaticity value is determined for all the points within the range of the white point. Data of driving voltage corresponding to each chromaticity value is obtained in advance and stored. The evaluator switches the white point using the above data. (C) It has knobs for adjusting the R drive voltage, the G drive voltage, and the B drive voltage, and these are manually adjusted by the evaluator so that the white point on the monitor becomes the target. The white point is controlled so that the value becomes.

[0005]

By the way, when the above-mentioned device (a) is used, since the white point is selected within a preset environment range, there is a problem that the environment in which the monitor is used is limited. there were. Further, when the device (b) is used, a great deal of labor is required to find the correspondence between the chromaticity value and the drive voltage, and in the case of a color CRT, for example, there is a risk that the correspondence may be broken due to deterioration of the phosphor or the like. It was In addition, it is necessary to determine which white point is suitable for the setting among a large number of white points, which takes time. Further, when the device (c) is used, it is difficult to know which voltage should be increased or decreased without sufficient knowledge, so that there is a problem that it requires considerable skill for adjustment.

The present invention has been made under such a background, and an object thereof is to provide an automatic white point correcting apparatus capable of automatically correcting the white point of a color monitor in accordance with ambient light. And

[0007]

An automatic white point correction device according to the present invention comprises an ambient light measuring means for receiving ambient light of a place where a color monitor is installed and measuring the color of the ambient light. A white point measuring means for receiving the reference white light displayed on the color monitor and measuring the white color; and a relative output between the ambient light measuring means and the white point measuring means. And a correction means for adjusting the emission intensity of each primary color at the white point of the color monitor so that the difference obtained by the calculation means becomes zero.

The white point automatic correction device according to the invention of claim 2 has a plurality of filters, receives ambient light of the place where the color monitor is installed, and decomposes it into a plurality of color components by the filters. An ambient light measuring unit that outputs a signal according to the intensity of each of the color components, and a plurality of filters are provided, and light from a white point displayed on the color monitor is received, and a plurality of colors are obtained by the filters. White point measuring means for decomposing into components and outputting a signal corresponding to the emission intensity of each of the color components, and a relative difference between the intensity of each color component in the ambient light and the intensity of each color component in the white point. Calculated by the calculating means based on the correspondence relationship between the calculating means for outputting, the light transmittance of each filter provided in the white point measuring means, and the emission intensity of each primary color of the white point of the color monitor. difference Compensating means for calculating the emission intensity balance of each primary color of the white point in the color monitor to make it zero, and adjusting the emission intensity of each primary color of the white point according to the balance of the emission intensity. Is characterized by.

In the white point automatic correction device according to the present invention, the calculating means may set the difference between the output signal of the ambient light measuring means and the output signal of the white point measuring means within a preset range. When it exceeds, the difference of the output signals is corrected within the above range.

[0010]

According to the invention described in claim 1, the relative difference between the color of the ambient light and the color of the white point of the color monitor is obtained, and according to the invention of claim 2,
By calculating the difference between the intensity of each color component in ambient light and the emission intensity of each color component in the white point of the color monitor, the chromaticity value of the white point of the color monitor becomes the chromaticity value of the ambient light. Adjusted to match, the appropriate white point adjustment is automatically made for any environment in which the color monitor is installed. Furthermore, according to the invention of claim 3, even when the chromaticity value of the ambient light exceeds a preset range, the white point is corrected to an appropriate white point.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. §1. First Embodiment FIG. 1 is a block diagram showing the arrangement of an automatic white point correction apparatus according to an embodiment of the present invention. In this figure, reference numeral 0 denotes an ambient light measuring means, which has at least three filters that satisfy the router condition and receives the ambient light, such as R, G, and B, like a stimulus value direct reading colorimeter. Each color component is separated and a signal corresponding to the intensity of each color component is output. Reference numeral 1 is a white point measuring means, and the light from the reference white displayed on the screen of the color monitor 2 is at least 3 as in the ambient light measuring means 0.
Each color component is separated by a filter of a sheet, and a signal corresponding to the intensity of each color component is output. The light receiving section R ₀ of the ambient light measuring means 0 is, for example, as shown in FIG.
It is provided upward so as not to receive the light generated from. Further, the light receiving portion R ₁ of the white point measuring means 1 is attached in close contact with the central portion of the screen of the color monitor 2 so as not to be influenced by ambient light.

Numeral 3 is a calculating means, which is supplied with the output signals from the ambient light measuring means 0 and the white point measuring means 1, calculates the difference between the respective signals, and outputs the difference signal. Reference numeral 4 denotes a correction unit that corrects the balance of the driving voltage of each of R, G, and B in the color monitor 2 based on the difference signal supplied from the calculation unit 3 to color the data supplied from the signal generation unit 5. Supply to the monitor 2.

Next, the white point automatic correction processing by the white point automatic correction apparatus according to the first embodiment of the present invention will be described with reference to FIG. For example, the color monitor 2 is installed under the ambient light represented by the spectral radiance distribution 6, and the current white point of the color monitor 2 is represented by the spectral radiance distribution 7. Further, each filter of the ambient light measuring means 0 has a spectral transmittance distribution 8 and each filter of the white point measuring means 1 has a spectral transmittance distribution 9. Here, the spectral transmittance refers to a rate at which each filter transmits light of each wavelength. The ambient light measuring means 0 and the white point measuring means 1 may be used in common. Each of these filters mainly transmits any one of the lights of the three primary colors of R, G, and B. For example, the filter having the characteristic of the curve 8a and the filter having the characteristic of the curve 9a mainly transmit R,
The filter having the characteristic of the curve 8b and the filter having the characteristic of the curve 9b mainly pass G, and the filter having the characteristic of the curve 8c and the filter having the characteristic of the curve 9c mainly pass B.

First, the ambient light measuring means 0 receives the ambient light shown in the spectral radiance distribution 6 and transmits it to each filter,
A corresponding output signal 10 is output. Here, assuming that the output signal 10 of each filter is signals Xa, Ya, and Za, Xa, Ya, and Za are given by the following equations. Xa = ∫kU (λ) · V _X (λ) dλ Ya = ∫kU (λ) · V _Y (λ) dλ Za = ∫kU (λ) · V _Z (λ) dλ However, in the above equation, k is It is a constant. Also, U
(Λ) is the spectral radiance distribution of ambient light 6, V _X (λ), V _Y
(Λ) and V _Z (λ) are the spectral transmittance distributions 8 of the respective color filters of the ambient light measuring means 0, which are functions of the wavelength λ of the incident light. Further, the white point measuring means 1 receives the white point of the monitor light shown in the spectral radiance distribution 7, transmits it through each filter, and outputs an output signal 12 corresponding thereto. here,
The output signal 12 of each filter is converted into signals Xm and Y, respectively.
m and Zm.

The above-mentioned signals Xa, Ya, and Za and the signals Xm, Ym, and Zm are calculated by the calculating means 3.
Each is normalized with the appropriate value of the corresponding signal. For example,
The output signal 10 of the ambient light measuring means 0 is normalized by the value of the signal Ya, and the output signal 12 of the white point measuring means 1 is normalized by the signal Ym. As a result, the normalized signal 11 and the normalized signal 13 whose color components corresponding to Ya and Ym are both 1 are obtained. Then, the difference for each color component in the normalized signals 11 and 13 is obtained, and the result is output as the difference signal 14. In FIG. 2, signals dX, dY, and dZ are illustrated as the difference signal 14 when the normalized signal 13 is subtracted from the normalized signal 11.

When the difference signal 14 is supplied, the correction means 4 increases the color component mainly transmitted by the filter corresponding to the signal dX, dY, dZ which is +. For example, as shown in FIG. 2, it is assumed that the signal dX and the signal dZ are +. This indicates that the white point of the color monitor 2 has less R component that mainly passes through the filter corresponding to the signal Xm and less B component that mainly passes through the filter corresponding to the signal Zm than the ambient light. .
In this case, the correction unit 4 controls the color monitor 2 so that the driving voltage of the R component is slightly increased. Or
The driving voltages of the other color components, that is, G and B are lowered. Then, the measurement is performed again, and the control of the drive voltage is repeated until the signal dX becomes zero. Similarly, for the signal Zm, the B component drive voltage is controlled until the signal dZ becomes zero. As a result, R is displayed on the color monitor 2.
The component and the B component are respectively (relatively) strengthened. In this way, the white point is corrected according to the chromaticity value of ambient light.

§2. Second Embodiment Next, an automatic white point correction apparatus according to a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, the correction means 4 has a correspondence relationship between the spectral transmittance 9 of each filter used in the white point measurement means 1 and the emission luminance of each color component on the color monitor 2, that is, each filter is connected to each color component. It is stored in advance how much is transmitted.
Based on this, the correction means 4 obtains the balance correction signal 15 indicating the ratio of the emission intensity of each color component according to the values of the signals dX, dY, and dZ. Then, the color monitor 2 is controlled based on the balance correction signal 15. as a result,
The white point of the color monitor 2 becomes like the spectral radiance distribution 16. In such a case, the correction can be performed more quickly than in the case where the control of the drive voltage is repeated until the difference signal 14 becomes zero.

[0018] Here, if the ambient light is a color having a considerably high degree of purity, or if it is a monochromatic light, the evaluator's visual system is not completely adapted to the ambient light and is then perceived by the evaluator. The white color is less pure than the fully adapted white color. That is, when the ambient light is a high-purity color, it is not necessary to make the difference signal between the color component of the ambient light and that of the white point completely zero. Therefore, it is necessary to limit the range of the chromaticity value of each color component controlled for adjusting the white point in advance.

The following is an example of the range of the chromaticity value. FIG. 4 is a diagram showing the relationship between chromaticity coordinate values (x, y) and color temperature in the CIE color system, and FIG. 5 is a chromaticity diagram in the CIE color system. In these figures, for example,
Limit to the range of chromaticity values when the visual system is fully adapted to ambient light. In the chromaticity diagram of FIG. 4, the correlated color temperature is 3500 [K] to 7000 [K], and the deviation ±
In the range 17 of 0.010 uv, or in the chromaticity diagram of FIG. 5, “white” including “yellowish white”, “greenish white”, “blueish white”, and “purple white”. The range 22 consisting of the range and the "light pink" is the movable range of the white point.

Hereinafter, the case where the ambient light has a higher purity toward R will be described. For example, it is assumed that the chromaticity value of the ambient light is outside the movable range of the white point, such as the chromaticity point 21 shown in FIG. 4 or the chromaticity point 25 shown in FIG. In this case, since the ambient light has many R components, the difference between the signal Xa output from the ambient light measuring means 0 and the signal Xm output from the white point measuring means 1 becomes large, and the calculating means 3 A differential signal 14 'as shown in 6 is calculated. Here, the difference signal 1 is set so that the movement of the white point is within the movement range described above.
4'is corrected like a differential signal 14 ". As a result, the balance correction signal 1 shown in FIG.
5'is required. Then, by the control of the correction means 4, the white point of the color monitor 2 is corrected as shown in the spectral radiance distribution 16 'shown in FIG.

At this time, the chromaticity value of the white point of the color monitor 2 is the intersection of the line connecting the predetermined white reference point 18 and the chromaticity point 21 with the line of the range 17 in FIG. Is represented by a chromaticity point of 20. The white reference point 18 is a perceptual achromatic color point (6000 [K]) experimentally obtained by a hunt or the like. Further, in FIG. 5, the white point is represented by a chromaticity point 24 which is an intersection of the line connecting the white reference point 23 and the chromaticity point 25 and the line of the range 22. In this case, the white reference point 23 is the reference white point ((x, y) = (0.310, 0.316)) in NTSC.

As described above, even when the ambient light is a color having a considerably high purity or is a monochromatic light, the chromaticity value of the white point is corrected within a preset range, so that an appropriate white color is obtained. The points are corrected.

In the first and second embodiments described above, the white point is automatically corrected by the correction means 4 based on the difference signal 14, but this difference signal 14 is used. The evaluator may manually perform the adjustment by providing a display unit for displaying and an adjusting unit such as a knob.

The white point automatic correction device may be used alone, or may be incorporated in a color monitor.

[0025]

As described above, according to the present invention, even if the environment in which the color monitor is installed changes and the color of the ambient light changes, it is not necessary to make difficult adjustments.
This has the effect of automatically correcting to a white point that matches the adaptation state of the evaluator's visual system. Further, since the chromaticity value of the white point actually displayed is measured by the white point measuring means, there is no influence due to deterioration of the phosphor or the like.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a white point automatic correction device according to a first embodiment and a second embodiment of the present invention.

FIG. 2 is a diagram illustrating an automatic correction process of the white point automatic correction apparatus according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating an automatic correction process of a white point automatic correction device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing the relationship between chromaticity coordinate values and color temperature according to the CIE color system.

FIG. 5 is a diagram showing a chromaticity diagram based on the CIE color system.

FIG. 6 is a diagram illustrating an automatic correction process of the white point automatic correction apparatus according to the embodiment.

[Explanation of symbols]

 0 Ambient light measuring means 1 White point measuring means 2 Color monitor 3 Computing means 4 Correcting means 5 Signal generating means 6,7 Spectral radiance distribution 8,9 Spectral transmittance distribution 10,12 Output signal 14 Difference signal 15 Balance correction signal

Claims (3)

[Claims] 1. An ambient light measuring means for receiving ambient light of a place where a color monitor is installed and measuring a color of the ambient light, and receiving a reference white light displayed on the color monitor,
White point measuring means for measuring the white color, computing means for outputting a relative difference between the output from the ambient light measuring means and the output from the white point measuring means, and the difference obtained by the computing means So that is zero,
A white point automatic correction device comprising: a correction unit that adjusts the emission intensity of each primary color at the white point of the color monitor. 2. A plurality of filters are provided to receive ambient light at a place where a color monitor is installed, decompose into a plurality of color components by the filters, and generate a signal corresponding to the intensity of each of the color components. It has an ambient light measuring means for outputting and a plurality of filters, receives light from a white point displayed on the color monitor, decomposes it into a plurality of color components by the filter, and emits light of each of the color components. White point measuring means for outputting a signal according to intensity, arithmetic means for outputting a relative difference between the intensity of each color component in the ambient light and the intensity of each color component in the white point, and the white point measuring means A white color in the color monitor for making the difference obtained by the calculating means zero based on the correspondence relationship between the light transmittance of each filter provided and the emission intensity of each primary color of the white point of the color monitor. A white point automatic correction means comprising: a correction means for calculating a balance of light emission intensities of respective primary colors of points, and adjusting a light emission intensity of each of the primary colors of the white point according to the balance of light emission intensities. 3. The calculating means, when the difference between the output signal of the ambient light measuring means and the output signal of the white point measuring means exceeds a preset range, calculates the difference between the output signals. The white point automatic correction device according to claim 3, wherein the correction is performed within a range.