Cesia is the name given to visual appearances related to the perception of different spatial distributions of light. Light radiation that is not absorbed by an object can be reflected or transmitted either diffusely or regularly. These interactions of light with matter are perceived with a greater or lesser degree of gloss (from a mirror to a matte surface, as the extremes), more or less transparent, translucent or opaque, at different levels of darkness (according to the light-dark axis).