Method of transforming the light-source color data and the non-luminous object color data

Claim 1

A method of transforming a light-source color on a color cathode ray tube (CRT) monitor to a spectral reflectance factor, the method comprises the step of: setting a Color Comparison Condition, in which a light-source color, surrounded with an achromatic lights-source color, on said color CRT monitor and a non-luminous object color, surrounded with an achromatic surrounding in a visual field, can be simultaneously observed; determining a spectral reflectance factor R C (λ) of an object, which can be perceived as matched with an arbitrary light-source color on said color CRT monitor under said Color Comparison Condition; and determining the spectral reflectance factor of said object from the spectral distribution I C (λ) of said arbitrary light-source color using the following formula: R C (λ) = I C (λ)/I G (λ)R G (λ)      (1), wherein: I G (λ) is the spectral distribution of the light-­source color, which is perceived as matched with a color chip, having a spectral reflectance factor R G (λ), under said Color Comparison Condition and is produced by emitting all three phosphors(red (R), green (G) and blue (B)) of said color CRT monitor; and I C (λ) is the spectral distribution of said arbitrary light-source color displayed on said color CRT monitor under said Color Comparison Condition.

Claim 2

A method of transforming a light-source color on a color cathode ray tube (CRT) monitor to a spectral reflectance factor, the method comprises the step of: setting a Color Comparison Condition, in which a light-source color, surrounded with an achromatic lights-source color, on said color CRT monitor and a non-luminous object color, surrounded with an achromatic surrounding in a visual field, can be simultaneously observed; determining a spectral reflectance factor R C (λ) of an object, which can be perceived as matched with an arbitrary light-source color on said color CRT monitor under said Color Comparison Condition; and determining the spectral reflectance factor of said object from the spectral distribution I C (λ) of said arbitrary light-source color using the following formula: R C (λ) = I C (λ)/I G (λ)R G (λ)      (1), wherein: I G (λ) is the spectral distribution of the light-­source color, which is perceived as matched with a color chip, having a spectral reflectance factor R G (λ), under said Color Comparison Condition and is produced by emitting all three phosphors(red (R), green (G) and blue (B)) of said color CRT monitor; and I C (λ) is the spectral distribution of said arbitrary light-source color displayed on said color CRT monitor under said Color Comparison Condition.

Claim 3

A method of mutually transforming red, green and blue (RGB) video drive signals of a color CRT monitor and CIE tristimulus values of a non-luminous object color, said method comprises the steps of: setting a Color Comparison Condition, under which a light-source color, surrounded with an achromatic light-source color on said color CRT monitor, and a non-­luminous object color, surrounded with an achromatic surrounding of a visual field, can be simultaneously observed; determining undetermined coefficients k R , k G and k B from both known CIE tristimulus values X,Y and Z of a non-luminous object color and the RGB video drive signals R C , G C and B C of a light-source color which is perceived as matched with said non-­luminous object color by the human eye under said Color Comparison Condition and is produced by emitting all three phosphors (red (R), green (G) and blue (B)) of said color CRT monitor)using the following formula: wherein: x R , y R and z R are chromaticity coordinates of red phosphor light of the color CRT monitor; x G , y G and z G are chromaticity coordinates of green phosphor light of the color CRT monitor; x B , y B and z B are chromaticity coordinates of blue phosphor light of the color CRT monitor; R C , G C and B C are the RGB video drive signals of the color CRT monitor; and f₁, f₂ and f₃ are functions (or the gamma correction functions) for transforming the RGB video drive signals of the color CRT monitor to values corresponding to the phosphor-light-intensity outputs; and mutually transforming an arbitrary light-source color on said color CRT monitor and a non-luminous object color which is perceived as matched with the arbitrary light-source color under said Color Comparison Condition by using said determined coefficients k R , k G and k B in said formula.

Claim 4

A method of mutually transforming red, green and blue (RGB) video drive signals of a color CRT monitor and CIE tristimulus values of a non-luminous object color, said method comprises the steps of: setting a Color Comparison Condition, under which a light-source color, surrounded with an achromatic light-source color on said color CRT monitor, and a non-­luminous object color, surrounded with an achromatic surrounding of a visual field, can be simultaneously observed; determining undetermined coefficients k R , k G and k B from both known CIE tristimulus values X,Y and Z of a non-luminous object color and the RGB video drive signals R C , G C and B C of a light-source color which is perceived as matched with said non-­luminous object color by the human eye under said Color Comparison Condition and is produced by emitting all three phosphors (red (R), green (G) and blue (B)) of said color CRT monitor)using the following formula: wherein: x R , y R and z R are chromaticity coordinates of red phosphor light of the color CRT monitor; x G , y G and z G are chromaticity coordinates of green phosphor light of the color CRT monitor; x B , y B and z B are chromaticity coordinates of blue phosphor light of the color CRT monitor; R C , G C and B C are the RGB video drive signals of the color CRT monitor; and f₁, f₂ and f₃ are functions (or the gamma correction functions) for transforming the RGB video drive signals of the color CRT monitor to values corresponding to the phosphor-light-intensity outputs; and mutually transforming an arbitrary light-source color on said color CRT monitor and a non-luminous object color which is perceived as matched with the arbitrary light-source color under said Color Comparison Condition by using said determined coefficients k R , k G and k B in said formula.