JPH0223396A - Converting method for conversion from light source color of crt color display to spectral solid angle reflection factor - Google Patents

Abstract

PURPOSE:To perform conversion to the spectral solid angle reflection factor of a body so that the same color as the color of a light source can be sensed by finding the spectral solid angle reflection factor of the body with which the same color as the optional color can be sensed in color comparison environment from the spectral distribution of light source colors by using a specific equation. CONSTITUTION:The spectral distribution of the light source color A is expressed by IG(lambda) when a color chart 4 which has a spectral solid angle reflection factor RG(lambda) which can be represented in an equal color state by the light emission of all of primary color fluorescent materials R, G, and B on the screen 1 of the CRT color display in color comparison environment and the light source color A sensed as the same color by a visual observation are displayed. Further, the spectral distribution of the light source color A when an optional light source color A is displayed on the screen 1 is expressed by IC(lambda) and the spectral solid angle reflection factor RC(lambda) of the body sensed as the same color as the optional light source color A is found from the equation I. Consequently, the conversion to the spectral solid angle reflection factor RC(lambda) of the body which can be sensed as the same color through the CRT 1 and the observation system for a body color B is carried out without using any color transmission medium.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application 1 The present invention calculates spectral solid angle reflection including spectral reflectance and spectral radiance factor from light source color data of colors displayed on a CRT display screen. Concerning conversion method to rate.

[Prior Art] In recent years, convenience stores have been using D+! color graphics devices (CG). In-line creation is now being done in a wide range of industrial fields such as 101, apparel, automatic middleware, home appliances, and printing, and not only the rough color design image but also the determination of an-design colors is now being done in CO. It has become to. For this reason, there is a need for technology that accurately transmits the color (light source color) determined by visual perception by the designer on the CG CRT color display screen to the production site, etc., as the corresponding object color or its data. It has become.

Conventionally, to convey colors on CG, a hard copy of the screen is created using a medium such as an inkjet printer or a photograph, and from this hard copy, the object color data, spectral solid angle reflectance or CIE three-point am, is obtained by measuring the object color. Based on this object color data, on-site color matching work such as computer color matching (CCM) processing is performed.

However, when light source color data is converted into object color data by using an octocopy as a color transmission medium in this way, the phosphor of a CRT color display and the ink used for hard copy and photographic y! Because the spectral characteristics of the colorant and other materials are different from each other, it is not possible to obtain a hard copy that accurately reproduces the color that the designer perceives on CG, and as a result, it is difficult to convert light source color data to object color data. In addition to being extremely inaccurate, there was a problem in that it was impossible to combine the design department and the color matching site, such as combining CG and CCM.

In the current situation where there are accuracy problems in color transmission using hard disks, a technology that transfers the color that the designer perceives and determines on CG from the CG side as object color data without going through a medium is attracting attention. ing.

CRT, which does not use a color transmission medium,
RG of the light source color displayed on the 7J R-f display screen
8 emission III all signals to object color CIE tristimulus value
A method using a conversion formula for converting to YZ is known.

[Problems to be Solved by the Invention] A3 of the above prior art is that the chromaticity point of white color at the time of CRT white balance is used to determine the conversion formula for the RGB light emission control signal and the object color CIE tristimulus button x, y, z. is used as the determining parameter for the undetermined coefficient in the conversion formula.

However, this method uses C
Standard white light (light with a chromaticity point that matches the chromaticity point during white balance) that is emitted in an environment such as a dark room where the surroundings of the RT are not perceived at all, and illuminates only objects placed in the vicinity. Prepare a white CRT and put one next to it.
In reality, C
The problem was that it was completely different from the RT observation environment, making it difficult to put it into practical use.

Therefore, the present invention aims to convert the spectral distribution of the light source color displayed on the CRT color display screen into the spectral solid angle reflectance of an object that can be perceived as the same color on the actual CRT and the AP system of the object color. The purpose is to provide a conversion method that can be performed without using a medium. Further, by determining the spectral solid angle reflectance, the CIE tristimulus values can be easily determined using a conventional method.

[One Step to Solve the Problems] The method of converting the light source color of the CRT color display to the spectral solid angle reflectance of the present invention is based on the method of converting the light source color displayed in the background color of achromatic light emission on the CRT color display screen. A color comparison environment is set up in which the color of the object and the object color in the achromatic background can be observed simultaneously, and under this color comparison environment, all of the three primary color phosphors R, 0, and 8 of the CRT color display emit light on the CRT color display screen. A color chart having a spectral solid angle reflectance RG (λ) that can be expressed in a W color state and a light source color that is perceived to be the same color by visual observation are displayed on the ship's screen.
Let the spectral distribution of this light source color be Ir,(λ), and let the spectral distribution of the light source color @lc(λ) be when an arbitrary light source color is displayed on the screen under the color comparison environment. According to the formula, the light source color spectrometer n1lc (λ) from the color comparison environment)
The spectral solid angle reflectance RC (λ) of an object that is perceived as having the same color as this arbitrary light source color is determined.

[Example] Embodiments of the present invention will be described below with reference to the accompanying drawings.

ff11 is a schematic explanatory diagram showing the basic concept of the present invention, and C
I'< T b ') - The view of the person observing the display screen 1 is, for example, under the observation condition f1 of the surface color of an object as specified in [1 Woodworking Mulberry Standard (JIS Z8723)] Set a color comparison rI4 boundary that allows you to visually observe object color B at the same time as the screen, and under this color comparison environment
3. Are the light source color A and object color B displayed on the CRT color display screen 1 the same as your eyes? It was invented based on the fact that when the color W is perceived by the JIIII dormitory, it is possible to accurately convert the light source color data to the light source color to the object color data of the object color B°, which is equivalent to the object color B. .

In Fig. 1, 2 is the illumination light source, 3 is the achromatic color of object color B**, 4, 4A are color charts representing the object color in broad daylight, and 5 is 12! I point, 6 is a toning area on the CRT screen 1 of the same size as the color chart 4° 4A, 7 is the back Wi color on the CRT screen 1, and this back m color 7 is perceived as an achromatic color. As far as the brightness is concerned, it is not limited and may be any brightness. 8 is the lighting! This is a light shielding plate that prevents the CRT screen 1 from being irradiated with the light 2.

In the 1J color comparison environment shown in Figure 1, illumination light 1112 is a standard C light source, 3 is N6.5 matte paper, 7 is N6.5 pine J-paper 3 is illuminated with a standard C light source 2, observation points 5 to N6 .5
Each is set so that the perceived brightness is equal to the perceived brightness when observing the matte paper 3, and first, under this set color comparison environment, the spectral solid angle reflectance RG (λ) is an achromatic color that is a known object color. Modified Munsell standard color chart 4Δ N9~N
2<brightness 15 tep) For the 8 images, the light source color (gray) that is perceived as the same color by visual observation is displayed in the toning area 6 on the CRT screen 1.
The spectral distribution 1c, (λ) is obtained to standardize the brightness scale determination of the light source color and object color. Figure 2 shows achromatic color chart 4A (N
Adding the spectral solid angle reflectance distribution diagram of 5), Figure 3 is the spectral distribution diagram of the light source color (gray) that is perceived to be the same color as the achromatic color chart 4A<N5) by standardized brightness scale judgment. It shows.

Next, CR any light source color △ under the one-color comparison environment shown in Figure 1.
Measure the spectral distribution IC (λ) of the light source color A displayed in the toning WA area 6 on the T screen 1 with an emission spectrometer, or
It is determined by the following formula by previously measuring the respective spectral distributions when the RT three primary color phosphors RGB emit light at a maximum of n degrees.

IC(λ)-1+ (RC) ・IR(λ)+f2
(Gc) ・Ie (λ) +f3 (BC) ・Is (λ) RC, Gc, Bc: CRT light emission II till signal IR, Xia e, Is: CR just three primary color phosphor RG8 reaches maximum brightness in China and Germany Spectral distribution 1'-1, f'2, f'3 when emitting light: CRT non
light! A function that converts the IJIIW signal into a coefficient corresponding to the actual brightness (gamma correction function) Spectral distribution IC (λ
), the spectral distribution IC, (λ) of the light source color (gray), and the spectral solid angle reflectance RC, (λ) of the achromatic color chart (N5) are substituted into the following equation (1) to obtain the light source color A. From the spectral distribution IC (λ), the spectral solid angle reflectance RC (λ) of the object color B', which is perceived to be dark blue in the light source color under the color comparison environment, is determined.

In this case, in order to compare the value obtained from equation (1) with the actually measured value, the light II color 8 is visually inspected under the color comparison environment.
When three colors, 5R5/14.5YR5/12 and 5PB5/12, for example, 5R5/14.5YR5/12 and 5PB5/12 are selected and used as test M colors, the modified Munsell standard color chart 4, which is the object color B that is perceived to be the same color by observation, is used as the test M color. (A> is the modified Munsell standard color chart 5R
A spectral distribution diagram of a light source color that is perceived to be the same color as 5/14 is shown, and Figure 4 (B) is a modified Munsell standard color chart 5YR5/1.
Figure 4 (C) shows a spectral distribution map of light source color A that is perceived to be isochromatic with Modified Munsell Standard Color Chart 5PB5/12. ing.

Figure 5<A) is a distribution diagram of the spectral solid angle reflectance RC(λ) of the object color B' which is equivalent to the modified Mannville standard color chart 5R5/14 obtained using the formula (11). (8) is (1)
Kisei Munsell standard color chart 5YR5/12 and 'i! determined by the formula! ? Figure 5 (C) shows the distribution of the spectral solid angle reflectance RC (λ) of the object color B°, and Figure 5 (C) shows the modified Munsell f! The distribution diagram of the spectral solid angle reflectance RG (λ) of the V-valent object color B' is shown, and the f5 diagram shows the spectral solid angle reflectance RC' (λ) of the Akisho Munsell mark rI! color chart 4A. A distribution map of (actually measured va) is shown for comparison.

Then, the spectral solid angle reflectance (I
GJ under an illumination light source with an object color B that contributes to C (λ)
The following formula (
2) and the spectral solid angle reflectance RC'(
Clt under a certain illumination light source with object color B having λ)
E color system 3I11! The lI spears X', Y', and Z' are determined by the following equation (3).

As a result, the following formula (4) holds true.

The results of confirming the establishment of equation (4) are shown in Table 1, and the chromaticity points in Table 1 are shown in the chromaticity diagram of Fig. 6, and the J[5
Table 2 shows the three attributes of color based on Z8721.

The color differences seen in Tables 1, 2, and Figure 6 are within the allowable error range for color match U in 1) visual observation under the color comparison environment in Figure 1. was confirmed.

However, λ) is the spectral distribution of the illumination light source 2.

× (λ), y (λ), 2 (λn represents a color matching function based on a 2-degree visual field or a 10-degree visual field XYZ system, and K4 is determined by the following equation (5).

Table 1 Note that the present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the gist of the present invention.

[Efficacy of invention I! ] The present invention is a spectral solid angle reflection method that allows all of the three primary color phosphors R, G, and B of a CRT color display to emit light on a CRT color display screen under a set color comparison environment and to represent the same color state. Color chart and eyes with rate RG(λ)? ! l
The spectral distribution of the light source color when the light source colors that are perceived to be the same color by observation are displayed on the screen is IQ (λ),
When an arbitrary light source color is displayed on the screen under the color comparison environment, the spectral distribution of light 1IIII color is IC (λ), and IC (λ), IaI (λ), and RC, (λ) are used. By determining the spectral solid angle reflectance RC (λ) of an object that is perceived to be the same color as this arbitrary light source color under the color comparison environment from the spectral distribution IC (λ) of the light WA color, the CRT color display Conversion from the spectral distribution of the light source color displayed on the lli surface to the spectral solid angle reflectance of an object that can be perceived as the same color on an actual CRT and the 12 quintillion system of object colors is performed without using any color transmission medium. We can provide the conversion method to perform. (Also, by determining the spectral solid angle reflectance, the CIF tristimulus values can be easily determined using a conventional method.)

[Brief explanation of the drawing]

1v4 is a schematic explanatory diagram showing the principle of the present invention, FIG. 2 is a spectral solid angle reflectance distribution diagram of an achromatic color chart (N5), and FIG. Spectral distribution diagram of light source colors perceived as isochromatic with N5), Figure 4 (Δ) (B)
(C) is a spectral distribution diagram of the light source color that is perceived to be the same color as the modified Munsell standard color chart, which is the object color.
) is the spectral solid angle reflectance converted from the spectral distribution of the light source color shown in Figure 4 (8) (B) and (C) and the modified Munsell PIA.
11Lf! FIG. 6 is a distribution diagram showing a comparison between the spectral solid angle reflectance of sheet A and the spectral solid angle reflectance. 1...C, RT lx pla display screen 2...
Illumination light source 3...Achromatic background of object color B 4.4A...Color chart 7...Achromatic background of light source color A A...Light source color B...Object color Kubo Tanaga Tanigawa Kenjun Furu Hata Watanabe - Masahiroji Naoki Attorney General Patent Attorney Mamoru Ushiki (C) Figure 4 Wavelength group m) Figure 3 Wavelength (nm) (A) Figure 4 Wavelength (nm) m) Figure 5

Claims (1)

[Claims] Setting up a color comparison environment in which a light source color displayed in a background color of achromatic light emission and an object color in an achromatic background can be observed simultaneously on a CRT color display screen,
Under this color comparison environment, the spectral solid angle reflectance R_G (λ) that can be expressed as the same color by all of the three primary color phosphors R, G, and B of the CRT color display emitting light on the CRT color display screen is calculated. The spectral distribution of the light source color when a light source color that is perceived to be the same color by visual observation as the color chart that is displayed on the screen is defined as I_Q(λ), and any light source color under the color comparison environment is Let the spectral distribution of the light source color when displayed on the screen be I_C(λ), and from the spectral distribution of the light source color I_C(λ) according to the following formula, it is perceived as the same color as this arbitrary light source color under the color comparison environment. Spectral solid angle reflectance R of the object to be obtained
A method of converting a light source color of a CRT color display to a spectral solid angle reflectance, the method comprising determining _C(λ). R_C(λ)=[I_C(λ)/I_G(λ)]×R_
G(λ)