Associative recall of images

Orthogonal projection operations in a linear vector space are shown to have a close relation to the processes by which optimal associative recall of patterned information can be implemented. Two association schemes, the autoassociative mapping and the associative encoding, are introduced. The latter has a bearing on pattern recognition, especially in the recognition of an optical image from a small fragment of it. Analytical expressions for the quality of the recollections are derived, and computerized demonstrations of associative recall with 3024-element optical images are presented. Some preprocessing principles of the images are studied, whereby the two-dimensional Laplacian is found very effective. This finding may have some connection to lateral inhibition effects occurring in biological visual systems.