File:Grey square optical illusion.PNG

Size of this preview: 772 × 599 pixels. Other resolutions: 309 × 240 pixels | 618 × 480 pixels | 989 × 768 pixels | 1,087 × 844 pixels.

Original file (1,087 × 844 pixels, file size: 143 KB, MIME type: image/png)

This is a file from the Wikimedia Commons. Information from its description page there is shown below.
Commons is a freely licensed media file repository. You can help.

This image was previously a featured picture, but community consensus determined that it no longer meets our featured-picture criteria. If you have a high-quality image that you believe meets the criteria, be sure to upload it, using the proper free-license tag, then add it to a relevant article and nominate it.

This image was selected as picture of the day on the English Wikipedia for November 5, 2004, February 19, 2005, and December 16, 2005.


	This formerly was a featured picture on the English language Wikipedia (Featured pictures) and was considered one of the finest images. See its nomination here. If you think this file should be featured on Wikimedia Commons as well, feel free to nominate it. If you have an image of similar quality that can be published under a suitable copyright license, be sure to upload it, tag it, and nominate it.

File:Checker shadow illusion.svg is a vector version of this file. It should be used in place of this PNG file when not inferior.

File:Grey square optical illusion.PNG → File:Checker shadow illusion.svg

For more information, see Help:SVG.

In other languages

Alemannisch ∙ العربية ∙ беларуская (тарашкевіца) ∙ български ∙ বাংলা ∙ català ∙ нохчийн ∙ čeština ∙ dansk ∙ Deutsch ∙ Ελληνικά ∙ English ∙ British English ∙ Esperanto ∙ español ∙ eesti ∙ euskara ∙ فارسی ∙ suomi ∙ français ∙ Frysk ∙ galego ∙ Alemannisch ∙ עברית ∙ हिन्दी ∙ hrvatski ∙ magyar ∙ հայերեն ∙ Bahasa Indonesia ∙ Ido ∙ italiano ∙ 日本語 ∙ ქართული ∙ 한국어 ∙ lietuvių ∙ македонски ∙ മലയാളം ∙ Bahasa Melayu ∙ မြန်မာဘာသာ ∙ norsk bokmål ∙ Plattdüütsch ∙ Nederlands ∙ norsk nynorsk ∙ norsk ∙ occitan ∙ polski ∙ prūsiskan ∙ português ∙ português do Brasil ∙ română ∙ русский ∙ sicilianu ∙ Scots ∙ slovenčina ∙ slovenščina ∙ српски / srpski ∙ svenska ∙ தமிழ் ∙ ไทย ∙ Türkçe ∙ татарча / tatarça ∙ українська ∙ vèneto ∙ Tiếng Việt ∙ 中文 ∙ 中文（中国大陆） ∙ 中文（简体） ∙ 中文（繁體） ∙ 中文（马来西亚） ∙ 中文（新加坡） ∙ 中文（臺灣） ∙ +/−

Summary

Description

An optical illusion. Square A is exactly the same shade of grey as square B. See demonstration.

Date

Original in 1995, this file in January 2004

Source

File created by Adrian Pingstone, based on the original created by Edward H. Adelson

Author

Original by Edward H. Adelson, this file by Gustavb

Permission
(Reusing this file)

The copyright holder of this work allows anyone to use it for any purpose including unrestricted redistribution, commercial use, and modification.

Please check the source to verify that this is correct. In particular, note that publication on the Internet, like publication by any other means, does not in itself imply permission to redistribute. Files without valid permission should be tagged with {{subst:npd}}.

Usage notes:

If the work requires attribution, use {{Attribution}} instead.
If this is your own work, please use {{Cc-zero}} instead.

File history

Click on a date/time to view the file as it appeared at that time.

	Date/Time	Dimensions	User	Comment
current	10:20, 24 May 2016	1,087 × 844 (143 KB)	Avayak	optimized losslessly
	21:13, 13 January 2008	1,087 × 844 (159 KB)	Mahahahaneapneap	pngcrushed
	03:54, 24 April 2007	1,087 × 844 (214 KB)	Jrockley	much larger version
	00:41, 9 April 2007	522 × 408 (70 KB)	Jrockley	Prepared for Wikipedia by Adrian Pingstone in January 2004, based on the [http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html original] created by Edward H. Adelson. See also [http://en.wikipedia.org/wiki/Same_color