Time-of-day perception in paintings

Area of Science:

• Visual Perception
• Art History
• Computational Imaging

Background:

• Daylight's spectral characteristics change predictably throughout the day.
• These variations in natural light influence object appearance and can signal time of day.
• Artists may utilize color choices to represent specific times of day in outdoor scenes.

Purpose of the Study:

• To investigate if viewers can accurately perceive the time of day depicted in paintings.
• To determine if image statistics, such as chromaticity and luminance, correlate with perceived time of day.
• To explore whether artists consistently employed specific color palettes to denote morning or evening light.

Main Methods:

• Conducted two online rating experiments with Western European paintings (17th-20th century).
• Experiment 1: Viewers rated paintings on seven time-of-day choices.
• Experiment 2: Viewers classified paintings as either morning or evening.
• Analyzed image statistics (brightness, contrast, saturation, hue) and correlated them with viewer ratings using multiple linear regression.

Main Results:

• Viewer ratings showed significant and consistent, though sometimes ambiguous (morning/evening), time-of-day perceptions across paintings.
• Image statistics correlated with perceived time: 'morningness' linked to higher brightness, contrast, saturation, and specific hue shifts (darker yellow/brighter blue); 'eveningness' to lower values and opposite hue shifts.
• A predictive model based on image statistics explained 76% of the variance in time-of-day perception.
• Experiment 2 confirmed that image statistics predicted perceived time (morning vs. evening).

Conclusions:

• Artists employed distinct color palettes and patterns to depict different times of day.
• The human visual system demonstrates consistent assumptions about natural light variations as represented in art.
• Color and luminance variations in paintings serve as reliable cues for decoding the depicted time of day.