On the Cover

Professor D. Alan Stubbs

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.