Evaluating colour image difference metrics for gamut‐mapped images

The quality of several colour image difference metrics, pixelwise CIELAB ΔEab, S‐CIELAB, iCAM, Structural Similarity Index, Universal Image Quality and the hue‐angle algorithm, have been investigated. These results were compared with the results from a psychophysical experiment in which the perceptual image difference was evaluated. Six original images were reproduced using six different colour gamut‐mapping algorithms. The results of our experiment indicate that perceptual image difference cannot be directly related to colour image difference calculated by current metrics. Therefore, it is currently not possible to evaluate colour gamut mapping quality using colour image difference metrics.