The dead time of a channel plate has been regarded so far as an inevitable defect in many applications; however, it is pointed out in this paper that it can be considered as the memory time during which the input image is stored. Line drawing, moving object detection, and inversion of images were performed by an experimental preprocessor using the dead time characteristics. The device should be recognized as a two‐dimensional operator with no scanning and without an electronic computer. The features of the device are very high‐speed operation and high sensitivity for dark images.