What is white?

Area of Science:

• Visual Perception
• Color Science
• Computational Neuroscience

Background:

• The perception of 'unique white' is fundamental to understanding color constancy and visual adaptation.
• Previous theories suggested white perception arises at the null point of cone-opponent mechanisms.

Purpose of the Study:

• To investigate the perceptual basis of unique white settings.
• To explore the role of visual environment calibration and illuminant uncertainty in white perception.

Main Methods:

• Measured unique white settings in a dark surround.
• Manipulated task type (absolute vs. relative) and surround color (dark vs. white) to alter illuminant uncertainty.
• Analyzed variability in color space, particularly in the blue-yellow direction.

Main Results:

• Unique white settings showed greater variability in the blue-yellow direction than along cardinal axes.
• Maximum variability locus approximated natural daylight loci.
• Sensitivity was reduced in the blue-yellow direction with a dark surround compared to a white surround.

Conclusions:

• White perception may not be a simple null point but involves calibration to the visual environment, particularly illuminant statistics.
• Variability in blue-yellow direction suggests adaptive mechanisms sensitive to illuminant uncertainty.
• Findings align with natural image statistics and propose potential neural mechanisms for color encoding.