A Proposal of Medium-Illuminant Dependency Evaluatio

摘要

The color of a recent print medium tends to be unstable under different illuminant conditions due to its sharp absorption of colorants in the spectral domain. We sometimes observe chromatic color for gray, which is originally adjusted to be achromatic under a specified illuminant condition. In order to quantitize the problem, we have proposed an evaluation method, namely Medium-Illuminant Dependency (MID) evaluation, which gives unstableness of a print medium under various illuminant conditions. In this method, firstly, the colors corresponding to real objects are estimated on a medium so as to have a metameric match under an illuminant condition. Secondly, the degree of metamerism of the pair under various illuminant conditions is calculated by industrial color-difference evaluation, ΔE_(94)~*. Lastly, some statistical values derived from them are regarded as the MID indexes of the print medium. We evaluated eight print media using 46 illuminant conditions. We found that the MID indexes have a low correlation with the sizes of color gamut, but have a high correlation with the fluctuation in the spectral domain at the range of 500 - 600 nm for achromatic colors.