Appearance defects

The forming of an image in a camera is above all depending on a fundamental optical characteristic of the surfaces : their bi-directional reflectance. This characteristic expresses the way surfaces have of reflecting the light they receive. because of its reflectance, an optical system will be very different if it is intended for a mat, bright or transparent surface, whether the color is uniform or not, etc...

The mathematical function for quantifying the behavior of a surface illuminated directly by a light source is referred to as BRDF (Bi-directional Reflectance Distribution Function).

The analysis of the BRDF gives particularly pertinent information characterizing the appearance of the surface and any visual defects in it.

The reflectance data of a surface make it possible to quality the appearance of a surface or of its visual defects.

Restitution of an object by artificially modifying its BRDF