SUMMARYAn electronic retina featuring DSP-like programmable analogue processing is addressed. The motivations for designing such an original smart image sensor are accounted for. The architecture of the circuit is described and then the two more important building blocks are detailed. Finally, the practical implementation and tests results are given so as to validate the approach.
MOTIVATIONSTo face the challenge of the image processing at video rate, numerous solutions were developed. The electronic retinas appear among one of the most prosperous axes of research [1][2][3][4][5]. Classically, the retinas are characterized by a completely parallel network of analogue operators that receive the signals directly stemming from photosensors. This total parallelism practically authorizes processing within a few milliseconds. Such an approach also o ers very low power consumption along with a high operative density. Besides, the variety of the analogue operators, linear or not, is far richer than those of digital systems. Nevertheless, in real applications, the exploitation of such architectures remains marginal. We attribute this lack of interest to the three following di culties.First of all, for a given silicon area, ÿnding a satisfactory compromise between the resolution and the completeness of the implemented analogue functions is a di cult task. This dilemma can either lead in two impasses. On the one hand, the retinas may o er a rich set of operators but at the expense of the resolution and the ÿll factor. Conversely, the circuit may feature an operative pan too much unadorned to a ord exploitable results.