RELATIONSHIP BETWEEN COLOUR RENDERING INDICES AND SUBJECTIVE COLOUR DIFFERENCES

摘要

CIE recommends R_a and R_i as indices of colour rendering properties in CIE13.3. But R_a and R_i have some problems to be considered. CIE224 was published to solve the problems above. But even the proposed index R_f has some technical issues to be considered, and R_f is not a replacement of R_a neither for the purpose of rating and specification of products nor for regulatory or other minimum performance requirements. In order to evaluate R_f a series of experiments comparing the correlation of R_f and R_a with the subjective colour differences was conducted. And it was made clear that both R_a and R_f are well correlated with the subjective colour differences. But under some illuminants, subjective colour difference is not same even if R_f is equivalent, and subjective colour difference is same even if R_f is not equivalent. These results are not seen in the case R_a. The calculated colour differences that is base of R_a and R_f are well correlated with the subjective colour differences but the slope of the regression line between the calculated and the subjective colour differences is different by the Test Colour Sample.