Abstract: A new structure comprising a layer of an imaging material, capable of undergoing an image forming change in response to energy, a layer of a barrier material and a layer of a catalyst material which, if necessary after activation, is capable of causing or promoting the image forming change in the imaging material. The barrier material is capable of controlling in accordance with a desired image pattern, the passage of the catalyst material through the barrier layer into contact with the imaging material in selected areas, while it prevents passage of the catalyst material in other selected areas.