Patent ID: 7256781

Claim:
An image processing apparatus for finding reflectivity based on a bi-directional reflection distribution function (BRDF) model expressing a ratio of reflection of light incident upon one point of a surface of an object to be drawn at the object surface, comprising: a first operation means for outputting a direction of a light source and a direction of a viewpoint; and a second operation means for calculating said reflectivity based on a BRDF model calculated by a quadratic-form matrix expression having the form of t ⁢ [ L V N ] ⁡ [ M ] ⁡ [ L V N ] wherein L is a vector corresponding to a light source direction vector representing the direction of the light source, V corresponds to a viewpoint direction vector representing the direction of the viewpoint, N corresponds to a normal direction vector, and M is a matrix corresponding to a parameter for determining the characteristics of the BRDF model.