LARGE COLOR DIFFERENCES IN COLOR REPRODUCTION - THE RELATIONSHIP BETWEEN PRINT ACCEPTABILITY AND COLOR-DIFFERENCE

The formulation of a metric to provide numbers that correlate with vis ually perceived colour differences has proved a very difficult task. M ost early experimental work was concerned with just-perceptible colour differences. Later the concept of perceptibility was expanded to acce ptability, it being argued that many industrial tolerances were larger than just-perceptible. This leads naturally to the concept of large c olour differences and the question as to whether the current CIE colou r-difference formulae, specified as appropriate for just-perceptible d ifferences, can be applied to the large differences experienced in the colour reproduction industry. This paper investigates the accuracy re quired of a large colour-difference metric as applied to photographic colour reproduction. It is shown that, within the limits imposed by a forced-choice experiment, the CIELAB colour difference of a scene elem ent compared to its reference, is proportional to the percent acceptab ility of that scene.