Gestalt in Isoluminance
Warning: this is somewhat subtle.
What to do & see
On the above there is a simplified version of the painting “Nu bleu II” by Henri
Matisse. The original is a medium blue on a light yellow background. Here, the background
brightness slowly oscillates and passes a point where the luminance of the background
equals that of the figure.
When the brightness of fore- and background is identical, the gestalt is suddenly
not well defined, it loses cohesion. The exact point of this so-called ‘isoluminance’
or ‘equiluminance’ depends strongly on your visual display unit and on your eyes.
You can narrow down the effect by clicking on the ‘Interactive’
button and manually adjusting the brightness with the slider.
Comment
I dimly recall the first demonstration of gestalt perception breaking down at isolumiance
was by Richard Gregory.
Sources
Thanks to Geoff Arden for many inspirations, and namely pointing me to this picture
to demonstrate the isoluminance effect.
Created: 2006-06-04
Last update: 2013-10-04