A 100×100 pixels orientation-selective multi-chip vision system

We describe a multi-chip analog VLSI system which emulates the orientation selective response of the simple cell in the primary visual cortex. The system consists of two analog chips, a silicon retina and an orientation chip, which mimic the parallel and hierarchical architecture of the visual system in the brain. The spatial resolution of the system is 100×100 pixels. The silicon retina receives the input image with a Laplacian-Gaussian-like receptive field. The output image of the retina is transferred to the orientation selection chip. The image transmission between two chips is carried out using analog signals. The orientation chip selectively aggregates multiple pixels of the silicon retina, mimicking the feed-forward model proposed to explain the orientation-selective receptive field of the simple cell. The orientation chip provides three output images with different preferred orientation in parallel. The analog multi-chip architecture used in the present study is useful to mimic the responses of higher order cells in the primary visual cortex.