The initial steps in the biological visual signal processing are the extraction of the edge position and its orientation of an object image. These edge detection capabilities can be simulated by semiconductor edge detectors. In this letter, two types of such detectors, i.e., concentric and directional ones for detecting edge and its orientation, respectively, are successfully fabricated using an amorphous silicon hydrogen alloy. The measured performance of these edge detectors is similar to that of the biological ones. A three‐dimensional image array, made by fabricating two‐dimensional amorphous silicon edge detectors on top of the single‐crystal Si very large‐scale integrated circuit is proposed, which can be used as the preprocessor of a smart vision system.