Image preprocessing in simulated biological retina

The mammal biological retina was simulated in order to study the local preprocessing of images. The direct visual pathway (photoreceptors, bipolar and ganglionar cells) and the horizontal units were considered. The on-center and the off-center pathways were simulated. The computer pro gram simulated the analogic non-spiking transmission between photoreceptor and bipolar cells, and between bipolar and ganglionar cells and the gap junctions between horizontal cells. A 64×64 photoreceptors retina was implemented (more than 16,000 units). This retina displayed contour extraction (Mach effect), auto adaptation to brightness, progressive disappearance of non moving images, reversed post-image, and even optic illusion (Herman grid). The simulation showed that the amacrine cells are necessary to ensure the localization of the brightness auto adaptation.