Good evening, everyone. 
This is my updated homage to Edward Adelson's famous illusion. The squares marked R and A of that rather fetching chequerboard baize are exactly the same shade of grey.
Best wishes,
RC.

This is my updated homage to Edward Adelson's famous illusion. The squares marked R and A of that rather fetching chequerboard baize are exactly the same shade of grey.
Best wishes,
RC.
