Memory colours and colour quality evaluation of conventional and solid-state lamps

Abstract

A colour quality metric based on memory colours is presented. The basic idea is simple. The colour quality of a test source is evaluated as the degree of similarity between the colour appearance of a set of familiar objects and their memory colours. The closer the match, the better the colour quality. This similarity was quantified using a set of similarity distributions obtained by Smet et al. in a previous study. The metric was validated by calculating the Pearson and Spearman correlation coefficients between the metric predictions and the visual appreciation results obtained in a validation experiment conducted by the authors as well those obtained in two independent studies. The metric was found to correlate well with the visual appreciation of the lighting quality of the sources used in the three experiments. Its performance was also compared with that of the CIE colour rendering index and the NIST colour quality scale. For all three experiments, the metric was found to be significantly better at predicting the correct visual rank order of the light sources (p < 0.1).

Light dominates colour preference when correlated colour temperature differs

“…A possible reason is that different gamut-based indexes adopt different colour samples for calculating the gamut area. If the colours sample were not reasonably selected, maybe the correlation between the subjective preference rating and the metric predictions would be masked 48,54 . Figure 6 illustrates another two findings of this work.…”

Effect of Window Glazing on Colour Quality of Transmitted Daylight

“…Feeling of Contrast index (FCI) [25] 5. Memory colour rendering index (MCRI) [26][27][28] 6. Preference index of skin (PS) [29] …”

“…The memory colour rendering index (MCRI) is the index based on memory colours [26][27][28], which are associated with familiar objects in long term memory. MCI used ten familiar objects; a green apple, a banana, orange, dried lavender, a smurf figurine, strawberry yoghurt, a sliced cucumber, a cauliflower, Caucasian skin and grey sphere.…”

Exploring the use of memory colors for image enhancement

“…Besides, memory colors are used in image segmentation 4, 18 and illumination quality evaluation. 19,20 However, the memory colors these techniques rely on are based on previous psychophysical experiments, which are not necessarily appropriate for image editing applications. The performance of memory colors in these techniques are not evaluated from a perceptual point of view.…”