reflection and is is the image intensity due to specular reflection the lambertian and specular components of image intensity can be expressed in terms of the parameters that describe the two dimensional imaging and illumination geometry shown in fig1 the result can be extended to the three dimensional case in two dimensions the source direction vector s surface normal vector n and viewing direction vector v lie in the same plane therefore any direction may be represented by a single parameter namely the zenith angle u03b8 the lambertian component il results from the non homogeneous nature of the object surface light rays penetrating the surface undergo multiple refractions and reflections and reemerge near the point of entry with a variety of directions these surfaces appear equally bright from all directions thus the intensity component il is independent of the viewing direction however the brightness of a lambertian surface point is proportional to the energy of incident light as seen in fig1 the amount of light energy falling on the element of the object surface 12 is proportional to the area of the surface element as seen from the point source position the lambertian intensity component il is a function of the surface orientation or normal direction u03b8 n and the source direction u03b8 s while it is independent of the viewing direction the specular component is is maximum when the angle of incidence of light equals the angle of reflection of light for a given source direction viewing direction and surface normal direction is may be represented by the function the parameter k in equation 3 represents the sharpness of specularity from a large number of experiments it has been observed that k gt 20 for most surfaces that.