I just tried it, with Bryce 3.1 . I textured the ground plane and a cube with a black-and-white cartoon that I had made a while ago. With the cartoon as diffuse color texture map, each face of the cube was a copy of the cartoon, and the ground plane had an infinite tesselation of the cartoon, as expected. But with the cartoon as bump map, all that happened was a line of `black' (i.e. a bump map groove) along the +X edge of where the cartoon shound have been; on the ground plane this produced an infinite pattern of thin parallel lines. Neither had apparent depressions in the shape of the cartoon image, although the sun was at a low angle.