Munker-White Illusion

White's illusion is an optical illusion illustrating the fact that the same target luminance can elicit different perceptions of brightness in different contexts. White's illusion is sometimes combined with the Munker illusion (a similar illusion that uses colors instead of grayscale) and referred to as the "Munker-White" illusion. (New World Encyclopedia)

White Illusion

White's illusion is an optical illusion illustrating the fact that the same target luminance can elicit different perceptions of brightness in different contextes. (New World Encyclopedia)

Rectangle on the right, look much darker than the rectangle on the left. However, Both rectangles reflect the same amount of light.
Description: White's illusion is made up of a series of black and white horizontal bars. On one side, shorter gray bars cover the black bars; on the other side, they cover the white bars. When observing the image, it appears as though the gray bars surrounded by white stripes are definitively lighter than the gray bars surrounded by black stripes. In addition to appearing lighter, the gray bars surrounded by white also appear to be brighter, or of higher luminance. (New World Encyclopedia)

Munker Illusion

Munker illusion is a similar illusion that uses colors instead of grayscale.

Note, that although the blue rectangles are all of equal luminance, the brightness of the blue rectangles appear to shift toward the brightness of the top and bottom bordering stripes

The proof of equal luminance ( same color intensity) in Munker-White Illusion.

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White's Illusion Munker-White Illusion

The black bars are removed with the Photoshop Elements' Magic Wand tool.

Bezold effect

The Bezold effect was first discovered by a German professor of meteorology, Wilhelm von Bezold (1837-1907), who discovered that a color may appear different depending on its relation to adjacent colors. Bezold discovered that contrary to the already established finding of "simultaneous color contrast" in which a color takes on the complimentary hue and contrasting brightness of its surroundings, Bezold discovered that under certain circumstances a colored region will take on the same color as its surround. (New World Encyclopedia)

Bezold effect

The Bezold effect is an optical illusion, named after a German professor of meteorology, Wilhelm von Bezold (1837–1907), who discovered that a color may appear different depending on its relation to adjacent colors.

Bezold effect
Wilhelm von Bezold shows that the same red color appearing either lighter or darker depending on the color adjacent to it. The red seems lighter combined with the white, and darker combined with the black. It’s actually the same red.

Bezold effect

When looking at a specific hue, it can appear to change in appearance depending on the colors that surround it. For example, a yellow box surrounded by blue will look darker than a yellow box surrounded by red. Often, the surrounded color seems to take on a tint of the color that surrounds it; red boxes surrounded by blue will appear more bluish than those surrounded by white. The colored regions assimilate their border color; the opposite of the contrast effect often found with brightness, and also with hue. (New World Encyclopedia)

Bezold effect

The proof of equal luminance ( same color intensity) in Bezold effect.

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Bezold effect

The black bars are removed with the Photoshop Elements' Magic Wand tool.