The effect of center and surround luminance, visual angle, edge blur, and contrast polarity on overall brightness perception

Brightness, the perceived amount of light within a luminous environment, significantly impacts the functional and aesthetic quality of the built environment. Previous studies have often used conditions that do not fully replicate real-world settings, highlighting the need for further research in this area to inform better lighting practices. This study investigates the overall brightness perception of larger combined stimuli consisting of a central shape and its surround for potential implications for architectural lighting design. An experiment with 42 participants was conducted to investigate the effects of luminance, visual angle, contrast (positive and negative), and edge blur (diffuse and sharp) on the perception of brightness using a two-interval forced choice method. The results suggested that surround luminance had a significant effect on brightness perception. Overall, higher surround luminance was perceived to be brighter. As the visual angle increased, the effect of surround luminance diminished in cases with higher surround luminance. Although the interaction effect of surround luminance and visual angle on brightness perception was significant, the simple main effect of visual angle was not statistically significant in the tested negative contrast conditions. The effect of edge blur depended on the visual angle. The study highlights the importance of careful consideration of luminance and visual angle in optimizing perceived brightness.