That post links to this one: http://www.squarefree.com/2004/03/05/color-constancy-illusion/ http://www.squarefree.com/2004/03/05/color-constancy-illusio... I k

That post links to this one: http://www.squarefree.com/2004/03/05/color-constancy-illusion/ http://www.squarefree.com/2004/03/05/color-constancy-illusio... I knew the gray-tone checkerboard but this is a very surprising illusion. I opened the image in Photoshop and had a hard time believing the effect: http://screenjel.ly/oHDkBcDFnoQ http://screenjel.ly/oHDkBcDFnoQ (video, no sound)