Visual appearance

The visual appearance of objects is given by the way in which they reflect and transmit light.

The color of objects is determined by the parts of the spectrum of (incident white) light that are reflected or transmitted without being absorbed.

Additional appearance attributes are based on the directional distribution of reflected (BRDF) or transmitted light (BTDF) described by attributes like glossy, shiny versus dull, matte, clear, turbid, distinct, etc.

The scattering of the frosted glass slightly increases the reflected luminance in the areas above and below the position of the lamp (indicated by the arrows).

This additional luminance is called haze or veiling glare.

Figure 2A: Specular, mirror like reflection. The inclination of the reflected beam is identical to the inclination of the incident beam.
Figure 2B: Reflection haze, the incident light beam is scattered about the specular direction. The intensity of reflection in the specular direction is reduced.
Figure 2C: Ideal (i.e. Lambertian) scattering of the incident beam. The reflected radiant power is constant for all angles of inclination.