Abstract: An image-forming agent selected from polyacids of molybdenum and tungsten and salts and complexes of these polyacids and disposed as a layer on at least one surface of a support substrate is reduced thereby being caused to undergo coloring in the form of an image and is then irradiated over its entire surface including thus colored parts and yet uncolored parts with long wavelength light rays which are absorbable by only the colored parts thereby to produce a colored image wherein the optical density of only the colored parts is selectively increased to a remarkable degree.

Abstract: There is provided an image-forming material of a laminar structure comprising:a substrate;an image-forming layer provided on at least one surface of the substrate and containing an image-forming agent selected from the group consisting of polyacids of molybdenum and tungsten and salts and complexes of these polyacids; anda transparent polymer film provided on the image-forming layer,at least one of the image-forming layer and the transparent polymer film containing a reducing agent.The image-forming material may be used in a one-stage image-forming process comprising irradiation thereof with image-wise light-rays including ultraviolet and visible and/or infrared rays or a two-stage image-forming process comprising irradiation thereof with image-wise ultra-violet rays and then with visible and/or infrared rays.