Skye’s Oblique Grating

from Michael’s   Visual Phenomena & Optical Illusions

What to see

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

What to do

• Deselect the checkbox “Check marks” – immediately the stripes become completely parallel.
• Deselect the checkbox “Odd reverse” – if unchecked, all the small diamond-checkerboards have the same orientation, and the effect vanishes.
• Exchanging (⇵) the colours between the horizontal & vertical grating also kills the effect.

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

Comments

This effect became popular in July 2017, originally designed by Victoria Skye, which I simplified a little for easier programming. It is interpreted as a version of the Café Wall illusion; however, 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).

Sources

Victoria Skye