Citation
BibTEX
@misc { npapadopoulos_optical_illusions_lightness_constancy,
author = "Nikolaos Papadopoulos",
title = "Optical Illusions, Lightness Constancy",
howpublished = "\url{https://www.4rknova.com/blog/2018/11/14/illusions-light-constancy}",
month = "11",
year = "2018",
}
IEEE
[1] N. Papadopoulos, "Optical Illusions, Lightness Constancy",
https://www.4rknova.com, 2018. [Online].
Available: \url{https://www.4rknova.com/blog/2018/11/14/illusions-light-constancy}.
[Accessed: 01-03-2025].
Table of Contents
Theory
Lightness constancy is the perception that brightness of lit and dark surfaces remains constant under different illumination conditions.
The human visual system interprets multiple visual queues and extrapolates sensory data. Our brain is good at recognising visual patterns including spatial queues and illumination features of the world around us.
The popularized “Checker Shadow Illusion” demonstrates the effect. A cylinder is strategically positioned on a flat surface with a checkerboard pattern. A light source is placed behind the cylinder and casts a shadow on the flat surface. The color intensity of the tiles under the shadowed area is doctored to match the lighter color of the checkerboard pattern. The viewer perceives the same color intensities as being different.
Implementation
Below is a live preview of my GLSL implementation. Click on the image to compare the tile colors.