Patent ID: 7821670

Claim:
An image processing apparatus comprising: a first calculation section that calculates a plurality of spectral reflectances at a plurality of wavelengths based on intensities of light illuminating an object and reflected from the object, the light having a certain spectral energy distribution; a second calculation section that calculates color descriptor values of the object based on the spectral reflectances calculated by the first calculation section; a third calculation section that calculates a set of factors when a color of the object is expressed using a set of color descriptor values generated based on the color descriptor values calculated by the second calculation section, each of the set of the color descriptor values expressed by a linear combination of a plurality of eigenvectors, the factors each associated with the respective eigenvectors, and either spectral energy of a reference light from a light source or theoretical spectral energy of a virtual light; and an output section that outputs the factors calculated by the third calculation section; and wherein the following equations are satisfied: X D65 = ∑ j = 1 6 ⁢ w j ⁢ ∫ vis ⁢ e j ⁡ ( λ ) · E 65 ⁡ ( λ ) · x _ ⁡ ( λ ) ⁢ ⁢ ⅆ λ Y D65 = ∑ j = 1 6 ⁢ w j ⁢ ∫ vis ⁢ e j ⁡ ( λ ) · E 65 ⁡ ( λ ) · y _ ⁡ ( λ ) ⁢ ⁢ ⅆ λ Z D65 = ∑ j = 1 6 ⁢ w j ⁢ ∫ vis ⁢ e j ⁡ ( λ ) · E 65 ⁡ ( λ ) · z _ ⁡ ( λ ) ⁢ ⁢ ⅆ λ X V = ∑ j = 1 6 ⁢ w j ⁢ ∫ vis ⁢ e j ⁡ ( λ ) · E V ⁡ ( λ ) · x _ ⁡ ( λ ) ⁢ ⁢ ⅆ λ Y V = ∑ j = 1 6 ⁢ w j ⁢ ∫ vis ⁢ e j ⁡ ( λ ) · E V ⁡ ( λ ) · y _ ⁡ ( λ ) ⁢ ⁢ ⅆ λ Z V = ∑ j = 1 6 ⁢ w j ⁢ ∫ vis ⁢ e j ⁡ ( λ ) · E V ⁡ ( λ ) · z _ ⁡ ( λ ) ⁢ ⁢ ⅆ λ wherein w 1 -w 6 are the set of factors, X D65 , Y D65 , Z D65 , X V , Y V , Z Z are the set of color descriptor values, e 1 (λ) to e 6 (λ) are the plurality of eigenvectors, E 65 is a spectral energy of a reference light from a light source, and E v is a theoretical spectral energy of a virtual light.