Color photometric stereo for directional diffuse object

Most objects of our interest in the field of photometric stereo not only may have colors on them but also may be non-Lambertian in reflection. Previously a photometric stereo method for a general class of color objects was reported. In this paper a photometric stereo method for a general class of non-Lambertian objects is presented with focus on directional diffusion. First, the condition to develop digital RAW image is described in terms of color temperature. Second, images of each color component are modulated in brightness in terms of gamma value so that the resulting shape has the same depth range as the ground-truth one. This makes it possible not only to get better shapes but also to characterize directional diffusion objects in terms of color gamma values.