ACHROMATIC COLOR DISCRIMINATION METHOD, COLOR ADJUSTMENT METHOD, COLOR IMAGE OUTPUT DEVICE, AND COMPUTER- READABLE RECORDING MEDIUM WITH PROGRAM FOR MAKING COMPUTER EXECUTE THE ACHROMATIC COLOR DISCRIMINATION METHOD OR THE COLOR ADJUSTMENT METHOD RECORDED THEREON

摘要

PROBLEM TO BE SOLVED: To provide an achromatic color discrimination method that discriminates an achromatic color, in matching with the visual characteristics of human beings. SOLUTION: The achromatic color discrimination method discriminates whether image data belong to a range permitted as an achromatic color, on the basis of the probability calculated by a Sigmoid function, where the image data are variables. Namely, this method adopts the probability expression employing the sigmoid, function to discriminate whether the image data reside in the range permitted as the achromatic color. Thus, the method can discriminate whether the image data have the achromatic color, while taking the visual characteristics of human beings into account.