In Shafer's dichromatic reflection model,^[1] scene radiance has two components:

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

λ is the wavelength,

c_b is the body (diffuse) reflected component,

c_s is the surface (interface) (specular) reflected component,

m_b and m_s are scale factors depending on illumination, view directions and surface orientation.