Shih-Chii Liu, Kwabena Boahen
Both vertebrate and invertebrate retinas are highly efficient in ex(cid:173) tracting contrast independent of the background intensity over five or more decades. This efficiency has been rendered possible by the adaptation of the DC operating point to the background inten(cid:173) sity while maintaining high gain transient responses. The center(cid:173) surround properties of the retina allows the system to extract in(cid:173) formation at the edges in the image. This silicon retina models the adaptation properties of the receptors and the antagonistic center(cid:173) surround properties of the laminar cells of the invertebrate retina and the outer-plexiform layer of the vertebrate retina. We also illus(cid:173) trate the spatio-temporal responses of the silicon retina on moving bars. The chip has 59x64 pixels on a 6.9x6.8mm2 die and it is fabricated in 2 J-tm n-well technology.