The crocs illusion is just plain wrong. It says "the correct answer is ". They then contradict themselves by saying it's green-gray. It's green-gray. Am I crazy? Any else's thoughts?
I wasn't too impressed with this one, either. In my mind, this illusion is much more straightforward demo of a similar effect (color perception being relative to surrounding colors): https://www.illusionsindex.org/ir/checkershadow
Yep, and it works for grey scale too.
This is the one I find the simplest:
http://3.bp.blogspot.com/-FLbAdn2URJs/Toim-B864TI/AAAAAAAAOc...
And a video of a similar effect: