Colour expectations across illumination changes.

Area of Science:

• Vision science
• Color perception
• Psychophysics

Background:

• Understanding human color expectations is crucial for color constancy research and applications in art and industry.
• Previous studies suggest color adjustments align with naturalistic illuminant-induced shifts.

Purpose of the Study:

• To investigate human expectations of naturalistic color changes under varying illuminations.
• To test if participants judge naturalistic illuminant and reflectance spectra as more plausible than artificial ones.
• To explore the role of relational color constancy in observer expectations.

Main Methods:

• Reanalysis of asymmetric color match data from a prior study.
• Three experiments using hyperspectral images of naturalistic scenes with manipulated illuminant and reflectance spectra.
• Observer judgments on the plausibility of naturalistic versus artificial color renderings.

Main Results:

• Observers selected naturalistic renderings above chance but only slightly more often than artificial ones when illuminant/reflectance were scene-wide.
• Observers more reliably identified naturalistic reflectance when only one object's reflectance was manipulated.
• Relational color constancy was found to contribute significantly to observer expectations.

Conclusions:

• Relational color constancy and prior knowledge of surface color shifts aid in identifying surface colors under illumination changes.
• Human observers can reliably recognize surface colors in naturalistic conditions due to these mechanisms.
• Relational color constancy demonstrates effectiveness in many artificial conditions as well.