Appearance of steadily viewed lights

Area of Science:

• Vision science
• Color perception
• Photometry

Background:

• Chromatic adaptation is a fundamental process influencing visual perception.
• Understanding hue, saturation, and brightness changes is crucial for visual science.
• Previous research has explored color constancy and adaptation effects.

Purpose of the Study:

• To investigate chromaticity and brightness variations after steady chromatic adaptation.
• To quantify hue shifts and saturation changes in spectral colors.
• To analyze brightness decrease independent of chromaticity.

Main Methods:

• Utilized an interocular matching technique for precise measurements.
• Employed steady viewing of a chromatic test light with identical adapting and testing colors.
• Ensured sufficient adaptation times for stable perceptual matches.

Main Results:

• Observed significant changes in hue, saturation, and brightness post-adaptation.
• Spectral colors appeared desaturated; hue shifts occurred towards green (546-570 nm) and red (586-670 nm).
• Brightness decreased by 0.8 log unit at 150 td and 0.3 log unit at 8 td, independent of chromaticity.

Conclusions:

• Chromatic adaptation demonstrably alters color appearance, affecting hue, saturation, and brightness.
• The observed hue shifts and brightness changes align with established visual perception frameworks.
• Further analysis within a two-process brightness framework and Bezold-Brücke effect measurements support these findings.