Stuart Anstis¹, Sae Kaneko², Patrick Cavanagh³; ¹UCSD, ²Hokkaido U, ³Glendon College, York U

A white or grey patch in a red surround looks green by simultaneous contrast. But a white disk centered in a rotating windmill of alternating red and white sectors looks faintly pink. And this pink spreads throughout the entire image. Reason: The trailing cyan after images of the red sectors quickly become the brightest regions in the image, so are taken as the anchor for ‘white’. They provide an index of the overall illumination that triggers a global recalibration of the achromatic point – a perceptual shift of the neutral white toward the color of the afterimage. Actual white areas then shift in the opposite direction and appear pink.