# Influence of color on glare perception revealed when seeing the sun through colored glazing

## TL;DR

This study shows that the color of glazing affects how people perceive glare from sunlight, with red causing the most discomfort.

## Contribution

The study reveals that color significantly influences glare perception and suggests that current glare models need improvement.

## Key findings

- Red glazing caused the highest glare reports, followed by blue, while green and neutral were least disturbing.
- Current glare models using photopic luminosity function are not effective for predicting color-based glare.
- Color appearance models and photometry systems showed better alignment with subjective glare reports but need refinement.

## Abstract

The influence of color on discomfort glare from daylight remains unknown, despite its known effects in electric lighting. This gap limits the ability to predict and mitigate glare in environments with colored glazing and filtered daylight. To address this, we conducted experiments in a controlled daylit office where 56 participants were exposed to four glare conditions induced by the sun visible behind the colored glazing. The conditions differed only in glazing color (red, blue, green, and neutral) towards the sun while having similar visual transmittance resulting in similar glare metrics across colors. Results revealed a strong influence of color with red glazing leading to the highest reports of glare, closely followed by blue, while green and neutral were perceived as least disturbing. These findings suggest that current glare models using photopic luminosity function as a spectral weighting are not effective enough and from this, we assume the Helmholz-Kohlrausch effect can apply to glare similar to brightness perception. To explore this, we tested three color appearance models and supplementary photometry system as alternatives. While these models aligned better with subjective glare reports, they require modifications for higher luminance conditions and need to be tested for wider range of stimuli.