Colour Science & Perception
what the eye settles, and what it cannot
Generator

The Cornsweet edge, with its luminance profile

The two plateaux are both #898989 and are flat to exactly — the profile below shows that everything which differs lies within a narrow band at the boundary. Cover the centre line and the two halves become obviously identical.
The Cornsweet edge, with its luminance profileThe two plateaux are both #898989 and are flat to exactly — the profile below shows that everything which differs lies within a narrow band at the boundary. Cover the centre line and the two halves become obviously identical.one value on the left, the same value on the rightluminance profileboth plateaux are #898989checked equal

Drawn at its defaults, in what the brain does that the numbers do not. It takes no options at all, so every essay calling it gets this exact drawing.

Called by 1 essay

the blast radius of changing it

What the brain does

Brightness is inferred from edges

The Cornsweet effect makes two identical regions look different by altering nothing except a narrow band at the boundary between them. Cover the boundary and the difference vanishes, which says the visual system is reconstructing surfaces rather than reading off intensities.

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