Checker shadow illusion
{{short description|Optical illusion}}
File:Checker shadow illusion.svg
File:Grey square optical illusion proof2.svg
The checker shadow illusion is an optical illusion published by Edward H. Adelson, professor of vision science at MIT, in 1995.{{cite web |url=http://persci.mit.edu/gallery/checkershadow |title=Checkershadow Illusion |first=Edward H. |last=Adelson |year=2005 |access-date=2007-04-21
|author1-link=Edward_Adelson |website=Perceptual Science Group|publisher=MIT
}} It showcases the relative and context-dependent nature of human color perception.
Description
File:Optical illusion greysquares.gif
The image depicts a checkerboard with light and dark squares, partly shadowed by another object. The optical illusion is that the area labeled A appears to be a darker color than the area labeled B. However, within the context of the two-dimensional image, they are of identical brightness, i.e., they would be printed with identical mixtures of ink, or displayed on a screen with pixels of identical color.
Related illusions
While being one of the most well-known contrast illusions, there are similar effects which cause two regions of identical color to appear differently depending on context:
- The Cornsweet illusion creates a boundary between two identically-shaded regions with a discontinuous gradient, resulting in the opposing sides appearing to be different.
- The Chubb illusion evokes this effect by surrounding zones with others of different, distinct shades, with the relative brightness or darkness of the surrounded area appearing different.
- An illusion closely related to the checker shadow illusion, which also relies on using implied visual shadows to seemingly darken a brighter region to the same color as a well-lit dark region, involves two squares placed at an angle, with the darker square being lit and the lighter square at an angle which receives poor light.{{cite web |url=https://slate.com/technology/2013/12/optical-illusion-shades-of-gray.html |title = Viral Illusion Will — and Should — Have You Doubting Your Eyes| date=7 December 2013 |author1-link=Phil_Plait |last=Plait |first=Phil |website=Slate |publisher=The Slate Group |access-date=2022-06-14}}
See also
References
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External links
- [https://deviantart.com/butisit/art/Checker-shadow-illusion-263331875 A high-resolution remake of the illusion]
- [https://www.youtube.com/watch?v=z9Sen1HTu5o Real-life simulation]
- [https://web.archive.org/web/20210322124126/http://persci.mit.edu/gallery/checkershadow/description Explanation of the effect]
- [https://archimedes-lab.org/color_optical_illusions.html Illusion of colors] – search for ‘simultaneous brightness contrast’
- [https://michaelbach.de/ot/lum-adelsonCheckShadow An interactive presentation of the effect]
- [https://mantlelabs.com/illusion An interactive click-and-drag demonstration of the effect]
{{Optical illusions}}