Parameter estimation of a reflection model from a multi-band image
The present paper proposes a method for estimating various parameters of a reflection model from a single image of an object taken by a multi-band CCD camera. It is assumed that the object's surface is composed of an inhomogeneous dielectric material and has the shape of a cylinder. The Phong model is used as the three-dimensional reflection model, and a six-color camera is used as the multi-band CCD camera. We show some features of the reflection model and the image histogram. The model parameters to be estimated are such parameters as (1) surface-spectral reflectance, (2) illuminant spectral distribution, (3) illumination direction, (4) specular reflection exponent, and (5) ratio of body to interface intensity. The reflection parameters are estimated by analyzing the histogram on the color signal plane and making a relationship between the histogram features and the spatial points. The feasibility of the proposed method is demonstrated in an experiment using a plastic object. Computer graphics images are produced on the estimated model.