Computing motion using analog VLSI vision chips: an experimental comparison among four approaches

The authors have designed, built and tested a number of analog CMOS VLSI circuits for computing 1D motion from the time-varying intensity values provided by an array of on-chip phototransistors. The authors present experimental data for three such circuits and discuss their relative performance. One circuit approximates the correlation model, one the gradient model, while a third chip uses resistive grids to compute zerocrossings to be tracked over time by a separate digital processor. All circuits integrate image acquisition with image processing functions and compute velocity in real time. Finally, for comparison, the authors also describe the performance of a simple motion algorithm using off-the-shelf components