Illustration from Scientific Research

Luminance gain control is necessary for stable perception of an object (soccer ball) across slow and fast luminance changes. Gain control through adaptation alone may not achieve luminance-invariant responses (black). The adaptation-driven response (blue) may underestimate stimuli in dim conditions (dashed blue), in addition to under- or overestimating them across fast luminance-changing scenarios. Thus, additional gain correction (green) achieves luminance-invariant perception at both slow and fast timescales.

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