Abstract
Making emissive displays look like reflective surfaces is one goal of “calm display” technology. It may be achieved by adjusting the colour appearance of the display to match that of paper, following changes in illumination and viewing conditions. A previous cross-media colour matching study (Kučera et al. VSS2019) found discrimination ellipses of 16×6 ΔEab size on average, with scatter in chroma up to 3.67× larger than in hue. The study suggested that given freedom to adjust luminance, observers selected higher chroma at higher luminance and vice versa. Matching duration was also unconstrained. Here we ask how fixed luminance and adaptation duration affect cross-media colour matching. Participants (n=49) viewed an IPS LCD display next to a white card (RAL 000 90 00), each sized 10°, in an enclosed achromatic booth illuminated by tuneable multi-channel LED lamps. Light from the lamps was prevented from reaching the display. Following an initial 2-min adaptation under D65 illumination, participants had 5 minutes under the test illumination to adjust the display’s chromaticity to match the white card. Every 30 seconds, the adjustment joystick was disabled for 30 seconds while observers adapted to the test illumination. The display luminance was fixed to match the white card. Six test illuminations with equal illuminance levels (D65 and saturated red, green, blue, cyan and yellow) were presented three times each in randomized order. Results: PCA analysis of matches shows that with fixed luminance, discrimination ellipses are 3.4× smaller than for matches with adjustable luminance, and the “super-importance of hue” effect weakens considerably, but least for blue illumination. Overall, the scatter remains larger than for same-media matches (cf Luo and Rigg) across all individuals and timepoints – discrimination ellipses span 8.56 × 3.94 ΔEab on average. Increasing exposure time improves accuracy and consistency of matches, but not for everyone.