An optical-lever technique was used to stabilize the retinal image, in order to determine spatial contrast-transfer functions for several modes of presentation of rectangularly and sinusoidally modulated bar patterns. These modes include a sudden replacement of a uniform field by a bar pattern, the replacement of a bar pattern by a uniform field, the intermittent presentation of a bar pattern at several repetition rates, and the sudden superposition of a uniform field on a bar pattern. Average retinal illuminances of 50 and 5 td were used. The outcomes of these experiments enable us to decompose the spatial contrast-transfer function for the case of normal vision into a branch due to the positive primary image and a branch due to a negative afterimage. The interaction of the primary image and the afterimage causes spatial transients in the image to be enhanced.
J. J. KOENDERINK, "Contrast Enhancement and the Negative Afterimage," J. Opt. Soc. Am. 62, 685-689 (1972)