Perceptual organization in colour perception: Inverting the gamut expansion effect

Area of Science:

• Visual Perception
• Color Science
• Psychophysics

Background:

• The gamut expansion effect describes increased perceived colorfulness of uniform targets against uniform gray surrounds compared to variegated surrounds.
• This phenomenon has been traditionally attributed to contrast adaptation mechanisms in the visual system.

Purpose of the Study:

• To investigate whether the gamut expansion effect is dependent on the uniformity of the target patch.
• To explore alternative explanations for the gamut expansion effect, specifically transparency perception.

Main Methods:

• Demonstration of a modified gamut expansion effect using variegated target patches instead of uniform ones.
• Comparison of perceived colorfulness under different surround conditions (uniform gray vs. variegated).

Main Results:

• The gamut expansion effect was observed to invert when uniform target patches were replaced by variegated ones.
• Perceived colorfulness of variegated targets was greater against variegated surrounds than uniform gray surrounds.

Conclusions:

• The findings challenge the traditional explanation of the gamut expansion effect being solely due to contrast adaptation.
• The results support the hypothesis that transparency perception mechanisms play a significant role in the gamut expansion effect.
• This suggests a more complex interplay of factors influencing color perception in complex visual scenes.