p112fig03.33 Various ways that spatial gradients in boundary webs can cause self-luminous percepts.  See the text for details.<BR>|| Boundary web gradient can cause self luminosity.  Similar to <I>watercolor illusion</i>. Gloss by attached highlight (Beck, Prazdny 1981), glare. (Bresan 2001) Double brilliant illusion, (Grossberg, Hong 2004) simulation. p111c2h0.5 "... This effect may be explained as the result of the boundary webs that are generated in response to the luminance gradients and how they control the filling-in of lightness within themselves and abutting regions. ... Due to the mutually inhibitory interactions across the boundaries that comprise these boundary webs, more lightness can spread into the central square as the steepness of the boundary gradients increases. ...".