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Mach card
Mach card A Mach card is a bent card display used to show that the same visual image can be seen with different apparent depth, such as convex or concave, and that this depth interpretation can change perceived brightness or lightness across its surfaces.
A Mach card is a bent card display used to show that the same visual image can be seen with different apparent depth, such as convex or concave, and that this depth interpretation can change perceived brightness or lightness across its surfaces. In the classic effect, unequal illumination across the card may go unnoticed in one depth percept but become obvious when the card is seen with the opposite depth.