Optical illusions show how we see | Beau Lotto
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Further reading 1
Caption notes
Beau Lotto uses tiles in apparent shadow to distinguish light reaching the eye from the reflectance a viewer wants to infer. The same incoming light can be consistent with different surfaces under different illumination.
Video or transcript source ↗Original passages · 2
Because if the tile in that shadow were in fact in shadow, and reflecting the same amount of light to your eye as the one outside the shadow, it would have to be more reflective -- just the laws of physics.If they're under the same light reflecting the same amount of light to your eye, then they must be equally reflective.