Colour-difference evaluation using CRT colours. Part I: Data gathering andtesting colour difference formulae

A large set of colour discrimination data based upon Cathode Ray Tube (CRT) colours was accumulated. The experiment was carried out to study the effec t changes in viewing parameters on perceived colour differences. It was div ided into sixteen phases. Each phase was conducted under a different set of experimental conditions including different sample sizes, backgrounds, fra mes, widths. and colours of separation between pairs of samples. For each p hase, 134 pairs of colours with average 2.7 CIELAB colour difference were s tudied The colours closely corresponded to the five colour centers proposed by the CIE. Each pair was assessed by, 10 or 20 observers using the gray, scale method. The visual results from the present study were also used to t est six colour-difference formulae: CIELAB, CMC, BFD, CIE94, LCD, and CIEDE 2000. The latter outperformed the other formulae and is the new CIE colour- difference equation. The current results were also compared with the other datasets based upon surface colours. The present results are consistent wit h those obtained for surface colours. (C) 2001 John Wiley & Sons, Inc.