Perceived colour differences in displayed colours Part 2: spatial differences in soft copy imaging

Abstract

This paper follows and extends previously reported investigations into the ability of observers to match surface colour samples by synthesis using red, green and blue stimuli provided by a cathode ray tube (CRT) monitor, controlled by a computer and adjusted by either an observer or the experimenter. Investigations are described into the ability of observers to perceive small colour perturbations applied to a colour patch, in the simultaneous presence of a reference and five other closely related patches, all the patches being displayed on a CRT computer display. Consistency is found between results obtained by different sets of observers at three locations, using local equipment for display. The results obtained are found to indicate sensitivities to perturbations that depend on the hue and chroma of the reference, and the hue direction perturbations. The surround to the colour patches is shown significantly to influence the sensitivity of observers to the perturbations, and this finding is related to predictions made using a colour appearance model. The data obtained are fitted by the observer response model hitherto successfully employed by the authors in previously reported investigations, and the goodness of fit is quantified statistically. Conclusions are drawn concerning the red, green and blue bit ranges and CIELAB colour differences of perturbations likely to be perceptible to observers in the presence of an unperturbed reference.

Keywords:

• colour differences
• CRT monitor
• spatial differences
• soft copy imaging