Neon color spreading

Neon color spreading is similar to the watercolor illusion, though the two are not to be confused with one another as they are produced in different ways.

One theory as to why this happens is that the simultaneous stimulation between the visual processing of lines and the color receptors in the eyes are not congruent.

[3] The neon color spreading effect works in a similar way to another illusion: illusory contours.

If contrasting colors are used, such as a yellow background with blue and black lines, the effect will be enhanced.

Long and short wavelength light, where the human eye is less sensitive to spatial detail, seem to enhance the effect.

In contrast to this, green and yellow tend to suppress the effect of neon color spreading when used in the same way.

The brightness conditions under which the color spreading figures are viewed change the perceived intensity of the effect.

[4] Ehrenstein figures are a good way of easily making persistent color spreading effects.

They are also good for showing examples of differences in hue between inner and outer lines and how they affect the neon color spreading illusion.

An example of neon color spreading. A blue inner circle appears within the black contours. In the actual image this area is white, which is made evident if the image is magnified. [ 1 ]
Blue circles replace the intersecting blue lines, especially when viewed from a distance.
An example of a circle created by color spreading.
Kanizsa's Triangle is created by illusory contours.
An example of different colored Ehrenstein figures.