Mach bands


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Related to Mach bands: Simultaneous contrast

Mach bands

(mäk)
pl.n.
Illusory bands of intensified lightness and darkness perceived adjacent to the borders of light and dark in a visual image, caused by image processing in the retina and optic nerve.

Mach bands

When a light area is separated from a dark area by a transition zone in which the brightness increases or decreases regularly and rapidly, two bands are seen: one light band next to the dark area and another dark band next to the light area. The appearance of these two bands, known as Mach bands, is attributed to lateral inhibition processes occurring in the retina. The phenomenon is usually demonstrated with a rotating disc with black and white areas separated by a zone of brightness gradient. Syn. Mach rings.
References in periodicals archive ?
Hence, a snake may focus more on the border, not because Mach bands are perceived, but simply because the border has more information than does either of the adjacent panels.
Today these illusory features are known as "Mach bands," and they compellingly explain why Giffen saw a gap at the inner edge of ring C that uncannily--and insidiously--affirmed the artifact in Guerin's photographs.
Contours and borders dominate human visual perception because edges are accentuated by these features, known as "Mach bands."