Hover your mouse cursor over the images to hide the irrelevant tiles. Zoom in close to the tiles and use your hands to cover the background to ensure the relevant tiles aren’t changing colors when hovering. This illusion will blow your mind!
(more on the “Checker Shadow” illusion from the MIT creator Edward Adelson: http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html)