METHOD FOR PRODUCING A SHADE CHART BY FRACTIONATING A COLOUR SPACE, RESULTING SHADE CHART AND USES THEREOF

摘要

In order to fractionate an 'effective' colour space (ECS), which corresponds to a set of 'basic' chromatic components (BCCs) intended for a particular industrial application, (1) the ECS is estimated by selecting a reference colour space (RCS) including the ECS and by determining the trichromatic co-ordinates (L1, a1, b1; L3, a3, b3 ...) of said BCCs in the RCS, by means of measurements of the full colour tones of each BCC and known calculations; (2) the CCBs, with the exception of white and black, are arranged in ascending order of shade to obtain a set of 'standard' chromatic components (SCCs) which are graphically positioned according to the co-ordinates a, b thereof; (3) the 'effective' chromatic components (ECCs) forming the outer boundary of the polygon with the largest surface area are chosen from said SCCs; (4) the boundary of an 'effective' volume sector (EVS) is determined in the ECS and for each pair, i.e. 'effective pair' (EP), of ECCs which are immediately adjacent on the graphic line (1, 3) and taken together with black (B) and white (W), said EVS being the one to which said EP corresponds; (4) each EVS is fractionated according to the average allowable overall operational colour difference (Δ E) for the industrial application under consideration; and (5) a reference (L, C, H) is assigned to each resulting EVS fraction, whereby the set of EVS fractions thus defined and identified forms the desired shade chart. The shade chart is particularly useful for reducing errors between instruments.