Present automatic stereocompilation instruments use electronic correlation techniques to match conjugate image areas in stereo photographs. Recent studies have demonstrated the possibility of performing the same task by means of coherent optical processing. This paper compares the merits and constraints of the two approaches. Each correlator system is described with particular emphasis on how control signals for precise automatic image registration and deformation correction can be generated and applied in the optical correlation system. It is concluded that automatic optical image correlation offers advantages over its electronic counterpart in simplification of the correlation computer and the ability to handle high photographic density. However, further work is needed to achieve optically the flexibility available with the electronic correlator.