Dichromatic reflectance model

In Shafer's dichromatic reflection model, scene radiance has two components:


 * $$ L(\lambda) = m_\mathrm{b} c_\mathrm{b}(\lambda) + m_\mathrm{s}c_\mathrm{s}(\lambda) $$


 * λ is the wavelength,
 * cb is the body (diffuse) reflected component,
 * cs is the surface (interface) (specular) reflected component,
 * mb and ms are scale factors depending on illumination, view directions and surface orientation.

BREN (body reflection essence-neuter) model based
Body essence is an entity invariant to interface reflection, and has two degrees of freedom. The Gaussian coefficient generalizes a conventional simple thresholding scheme, and it provides detailed use of body color similarity.