from Hacker News

Click the Pic - How does this work?

by oo7jeep on 1/13/14, 7:50 PM with 1 comments

• by valtron on 1/13/14, 8:04 PM

  It's composed of two images with transparent backgrounds. The foreground on one of the images consists only of white, and on the other only of black. Depending on what color's behind the picture, it obscures one or the other.

  Edit: Gray background: https://twitter.com/SciencePorn/status/422565255726641152/ph...