Abstract

The effect of different parts of the surround on the appearance of a central test area was measured by the following method: The observer viewed a central disk surrounded by a radial sine wave: i.e., along any radius through the center, the color of the surround varied sinusoidally in space. As the phase of the sine wave was changed so that it appeared to drift toward the center, the appearance of the center changed cyclically in time. The induced modulation was nulled by adding real temporal modulation to the disk. The amplitude of the nulling modulation was expressed as a function of the spatial frequency of the surround. The spatial weighting function for the induced contrast was obtained by the inverse Fourier transform of this function in those cases where the total induced effect in the central test area was a weighted average of the effect of each pixel of the surround, and the effect of each pixel was proportional to the change in amplitude at that pixel. The validity of these conditions was tested by measuring the effect of the superimposition of surrounds of different spatial frequency. Results are presented for both brightness and chromatic induction.

© 1988 Optical Society of America