Figure 7.

Model simulations of binocular luminance summation of luminance discs with asymmetric contour information. (A) Luminance response of a nonflat CSF following luminance compression for a luminance disc (8 cd/m² luminance increment from dark background) with (blue) or without (red) a concentric circle. (B) Local contrast output of three LoG filters following luminance compression for a luminance disc (8 cd/m² luminance increment from dark background) with a concentric circle. (C) The disc size effect on binocular luminance summation: LE weight in luminance summation as a function of disc size (replotted from Figure 5D). The RE views the luminance, fixed at 72 cd/m², of a square of 14° × 14° on the dark background (0.2 cd/m²), and the LE views a central disc of variable size (1°, 3°, 5°, 7°, 9°, 11°, 13° in diameters), with luminance fixed at 12 cd/m², plus a surrounding square of 14° × 14°, with luminance fixed at 3.7 cd/m², on the dark background (0.2 cd/m²). The sum of the two eyes' weights equal one. The star markers show the results from Levelt (1965). Both simulation and data show that the LE has more weight in the luminance summation, and that the LE's weight decreases when the disc size increases.