What to see

The blue horizontal stripes above are oblique – are they? In my eyes an amazingly strong effect.

What to do

A number of further parameters can be adjusted (within limits) to modulate illusion strength. The “Center marks” aren't doing much for me. In Victoria's version there are even more such decorations.


This effect became popular in July 2017 and seems to have been originally designed by Victoria Skye, which I simplified a little for easier programming. I have not found this particular design on her site, but here. There and at other places this is interpreted as a version of the Café Wall illusion. I do not think this is correct – the mortar lines are missing here. The angle illusion is caused by the small check marks, and that effect was first demonstrated (I think) by Akiyoshi Kiatoka (my animated version here).


Victoria Skye


Created: 2017-08-09

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Last update 2017-08-10 by Michael Bach (G+)