Ken-ichi Ohta

Color appearance matching in hard-copy and soft-copy images in different office environments

This paper describes a method for matching the color appearances of hard copies and soft copies in ordinary office environments where lighting conditions usually vary. To develop this method, we studied ways of easily calculating the colorimetric values of hard copies under an arbitrary illuminant. In this report, we converted the colorimetric values of hard copies taken under a reference illuminant to the colorimetric values taken under a viewing illuminant by using a 3-by-3 matrix. The conversion matrix CR under an arbitrary illuminant is calculated by using the following equation: CR equals IH X CRh + (1-IH) X CRl. Here, CRh represents a conversion matrix for a high color-rendering illuminant, and CRl represents a conversion matrix for a low color-rendering illuminant. IH is the coefficient that represents the mixture ratio of high and low color-rendering illuminants. We calculated the colorimetric values of a hard copy under an arbitrary illuminant by using the above method, performed a color adaptation correction, and displayed the soft copy on a monitor. The color appearance of the soft copy matched that of the hard copy well under various illuminants.