In the present study, attempts were made to investigate the effect of colour difference magnitude on colour difference perception of pairs with no separation. To this end, a large number of printed sample pairs with no separation were prepared around 11 CIE recommended colour centres. The sample pairs, representing four colour difference magnitudes of 1, 2, 4 and 8 CIELAB units, were visually evaluated by a panel of 19 observers using the grey scale method. By comparing the present data set with those previously published using pairs with hair-line separation, it was found that separation had a certain impact on colour difference perception. The visual data were used to test the performance of five colour difference formulae: CIELAB, CIE94, CIEDE2000, CAM02-UCS, and CAMI6-UCS. A clear effect of colour difference magnitude on total colour difference perception of pairs with no separation was revealed and a generic simple equation was modelled. By introducing this, a new colour difference equation as the modification of CIEDE2000 was proposed for pairs with no separation. The new formula was found to perform much more precise than the original formulae.
Fereshteh Mirjalili, Ming Ronnier Luo, Guihua Cui, Ján Morovic, "A parametric colour difference equation to evaluate colour difference magnitude effect for gapless printed stimuli" in Proc. IS&T 26th Color and Imaging Conf., 2018, pp 123 - 127, https://doi.org/10.2352/ISSN.2169-2629.2018.26.123