This paper describes work directed at utilising the parallel processing power of relatively simple analogue optical systems, to improve the capability, compactness and cost of machine vision systems. We are investigating methods which allow the combination of the best features of both electronic and optical systems in such a way that the control and decision-making are performed by the digital electronic system, whilst the parallel computations and data reduction are performed by analogue optical means. The resulting machine is termed a hybrid processor. Figure 1 shows a generalised block diagram of the Optical Functional Unit of such a system.