Edge-induced colour spreading

In Flank transparency: The effects of gaps, line spacing, and apparent motion by Daniel Wollschla, Antonio M Rodriguez and Donald D Hoffman, (in Perception, 2002, volume 31) , they use the term neon color spreading to refer to “the perceptual phenomenon of color that seems to disperse from image elements into their surround, thereby creating a subtle neon-like veil”, explaining that “the observed coloration overcomes `real’ figure boundaries and typically covers an area confined by subjective contours”. Here’s an example:

The authors contrast this classical neon-color-spreading phenomena with edge-induced color spreading as discussed by Pinna, Brelstaff and Spillmann (in Surface color from boundaries: A new `watercolor’ illusion‘ in Vision Research 41, 2001) where edge or flank-induced coloration does not display the neon-like quality and much more resembles pastel surface colours or a watercolour wash. In doing my own drawings I have become especially interested that the area covered by the `diffused watercolor’ can be much larger than the area that might usually be the case with neon color spreading. And I keep asking myself why I have never come across this before.

The light green ‘ground’ in this image is constructed by you the viewer in response to the colours that flank the drawn figures. Note that the ‘ground’ also shifts to ‘figure’, creating an alternative view of the image.

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