An imaging medium comprises means for providing a light-reflecting layer, an image-receiving layer for receiving image-forming components, a transparent layer superposed over the image-receiving layer such that an image in the image-receiving layer can be viewed through the transparent layer against the light-reflecting layer, and an image enhancement layer disposed between the image-receiving layer and the transparent layer, the image enhancement layer having a refractive index less than that of the transparent layer and the image-receiving layer and not greater than about 1.43. The image enhancement layer decreases internal reflections within the medium and thereby improves the quality of the image seen. The imaging medium can be used as the imaging element of a diffusion transfer process film unit.