As longtime readers of this blog will know, I love optical illusions, and the checkerboard shadow illusion is one of my all-time favourites. If your not familiar with it, here's a rendering of the illusion done in Maya I found online; note that squares C3 (a white square) and B5 (a grey square) look as different as you'd expect in the top frame, but when you add a shadow-casting cylinder to the scene the two squares are almost exactly the same shade of grey onscreen, despite what your eyes are telling you.
While the illusion is real (and demonstrates effictively that you can't always believe what your eyes tell you about colour), there's something fishy going on in this real-world recreation of the scene:
The whole point of the illusion is that the middle tile is actually white, and appears white to our brains, but is dark grey on-screen. Yet the woman in the video drags the white tile to a dark tile, where it should definitely appear as a different color in the better-lit area. I guess they're maintaining the RGB color of the dragged tile in CGI, but I don't think this really helps to explain the illusion.
Anyway, that's all for this week (but you can check out older Friday posts here). We're back on Monday.