The present invention provides an image receptor element for dye diffusion transfer imaging processes, which comprises a support and an image-receiving layer incorporating a hydrophilic colloid and a mordanting polymer having quaternary ammonium groups and comprising polyalkylpiperidine units, which polymer is capable of fixing acid dyes transferred to said image-receiving layer by diffusion. The present invention also provides a monosheet light-sensitive color photographic element comprising as integrating constituents a light-sensitive element and such an image receptor element.