Patent US 5,090,909

Sources of video signals representing an object (e.g. an aircraft), optionally movable, and a scene provide data stored in frame stores (b 1,5). Distance (optionally variable) from the observer of the object and near and far distances at transitions between features in the scene are stored respectively in frame store (4) and (7a, 7b). Within the boundaries of the object and in the neighborhood of the lines of transition, between features of the scene, quantities stored in object and scene stencil frame stores (3, 6) vary from 0 to 1. All frame stores are read simultaneously, driven by a microprocessor (2), the picture point scanning element sequentially. A comparator (11) compares distances, and the results of the comparison, together with the values stored in the stencil frame stores, determine the tone displayed at each element. Near features obscure distant ones, and sharp transitions are softened.