Abstract

Many perceptual phenomena and visual illusions can be understood-in terms of mechanisms that extract different kinds of energy. Photoreceptors are tuned for spectral energy, and cells in cortex can be considered to be tuned for local pattern energy corresponding to texture, scale, orientation, motion, and so on. Even though the tuning tends to be broad, exquisite sensitivity can be achieved by comparing the outputs of such cells. Thus we can discriminate colors that differ by a single nanometer or lines that are offset by a fraction of a cone width. Comparison mechanisms also lead to a wide range of remarkable illusions and aftereffects in the domains of color, brightness, motion, and form.

© 1987 Optical Society of America