Identical gray patches displayed on contrasting light and dark backgrounds.

Light & contrast / 19th century

Simultaneous contrast

One gray looks light; the same gray looks dark.

TRY THIS

Compare the small gray patches against their light and dark backgrounds. Isolate them from the surrounding areas to check their shade.

ORIGIN / ATTRIBUTION

Longstanding phenomenon; studied by Michel Eugène Chevreul

19th century

The story behind it

Simultaneous contrast has a long history in art and visual science. Michel Eugène Chevreul’s nineteenth-century work, informed by problems with dyed textiles, made surrounding-color effects influential for artists and designers. The familiar gray-patch diagram illustrates the broader phenomenon rather than a uniquely authored original artwork.

What’s happening?

Brightness judgments depend on context. A gray region on a dark field can appear lighter than the same gray on a light field. Spatial contrast processing helps explain the effect, but full lightness perception also depends on interpreted surfaces and illumination.

A NOTE ON THE HISTORY

This is a family of effects, not a single image with one securely identified inventor.

brightnesscontextChevreul

FOLLOW THE SOURCES

History, evidence & image credit

THE IMAGE IN THIS ARCHIVE

This hand-written SVG version by Qef Original bitmap version by English Wikipedia user Xanzzibar Based on a similar bitmap image by K. P. Miyapuram

Original file & attribution · Public domain

Original image downloaded from Wikimedia Commons; the downloaded file is unchanged. Gallery previews may be resized or converted to WebP; animated previews show the first frame.

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