Films are disclosed which are constituted essentially of iodides of heavy metals to which catalysts or sensitizing agents are added to make the films highly sensitive to light and current at room temperature, thus increasing the speed of writing and erasing cycles. The disclosure provides for producing and erasing images on such light and current sensitive films prepared on substrates such as ordinary paper or transparent non-reactive materials. Marking on the films is achieved by light e.g., laser beam and Xenon lamp, or electrical current. Exemplary erasing is done by application of heat. Several examples are disclosed of the formation of these films adherently on non-reactive surfaces.