## Tuesday, January 5, 2010

### Refrak.

To define visibility, we examine the case of a perfectly black object being viewed against a perfectly white background. The visual contrast, CV(x), at a distance x from the black object is defined as the relative difference between the light intensity of the background and the object
${C_V}\mathrm{\left({x}\right)}\mathrm{{=}}\frac{{F_B}\left({x}\right)\mathrm{{-}}{F}\left({x}\right)}{{F_B}\left({x}\right)}$