1. A Boundary Contour System for detecting the boundaries of images having contrast distribution comprising: (a) mask means responsive to signals corresponding to said contrast distribution for weighting such signals with an orientational weighting function to produce mask output signals proportional to the degree of orientational congruence between the weighting function and the contrast distribution; (b) node means responsive to said mask output signals for enhancing said mask signals by suppressing the strength of mask output signals emanating from regions of the image of homogeneous contrast distribution to produce enhanced orientational mask signals; (c) feedback means responsive simultaneously to the orientational signals emanating from either side of spatial domains about a region of said image for generating a feedback signal to said node means when the orientated signals from both sides of said spatial domains are of sufficient value and orientation to indicate that a boundary contour is present in the region of the image between said domains.