Vision Experiment on Verification of Hunt Effect in Lighting

Hunt Effect is a phenomenon in which object colours at low light levels are perceived less saturated compared to that at higher light levels. If this effect is effective at normal indoor lighting levels, increasing the chroma saturation level at indoor lighting to some extent would make colour appearance of objects closer to that under outside daylight, thus bring higher fidelity of colours. To verify whether the Hunt Effect is effective at normal indoor lighting, vision experiments were conducted using a spectrally tuneable lighting facility simulating a real size interior room. Observers viewed real fruits and vegetables and their skin tones under different chroma levels in red-green direction at illuminance levels of 100 lx and 1000 lx, and evaluated naturalness of these targets. The results showed significant differences between 100 lx and 1000 lx; subjects perceived objects as most natural at less chroma level at 1000 lx than at 100 lx.