CHROMATIC DISCRIMINATION THRESHOLDS OBSERVED IN CAM02-UCS AND CAM16-UCS

In our study chromatic discrimination thresholds of normal colour observers measured with the Trivector test of the Cambridge Colour Test were analysed. Chromaticity coordinates were transformed from the CIE (1976) u’v’ diagram to the CAM02-UCS and CAM16-UCS colour spaces, where colour differences were calculated. The measured data consisted of chromatic discrimination thresholds measured in 66 reference points covering the gamut of a CRT display. The test directions were set to the confusion axes towards the Protan, Deutan and Tritan confusion points. Our results show variance in the ΔE values expressed both in the CAM02-UCS and CAM16-UCS colour spaces. Since our input chromaticity values described previously measured just-noticeable stimuli – therefore perceptually equal colour differences – we assumed that our data show equal colour differences in the uniform colour spaces. However, the discrimination thresholds transformed to CAM02-UCS and CAM16-UCS show that colour differences increase towards the chromaticity of the adapting light.