On the Cover
Professor D. Alan
Professor of Psychology and artist D. Alan Stubbs creates 3D digital
images to teach concepts of perception. His images, like the one on the
cover, called DynLumEngArt, "work" by having the viewer physically move
closer to and away from them. The result is that the center of the image
appears to brighten. The same illusory effect occurs in the DynLumEffect
images on the computer screens surrounding Stubbs. The colors, number
and size of the lines appear to have no effect on the illusion.
Gradation of the boundaries — graded change of luminance — appears to be
a key to the now-you-see-it, now-you-don't effect.