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 light that are reflected or transmitted without being absorbed. Additional appearance attributes are based on the directional distribution of reflected or transmitted light described by attributes like glossy, shiny versus dull, matte, clear, turbid, distinct, etc.

Appearance of reflective objects

The appearance of reflecting objects is determined by the way the surface reflects incident light. The reflective properties of the surface can be characterized by a closer look at the -topography of that surface.
Structures on the surface and the texture of the surface are determined by typical dimensions between some 10 mm and 0.1 mm. Smaller structures and features of the surface cannot be directly detected by the unaided eye, but their effect becomes apparent in objects or images reflected in the surface. Structures at and below 0.1 mm reduce the distinctness of image, structures in the range of 0.01 mm induce haze and even smaller structures affect the gloss of the surface.

Basic types of light reflection

Figure 3 : Light source reflected by a smooth glass surface and a scattering surface with micro-structures. A distinct image of the lamp is only provided via reflection without scattering.
The scattering of the frosted glass slightly increases the reflected luminance in the areas above and below the position of the lamp. This additional luminance is called haze or veiling glare.		Figure 4 : Profile of reflected luminance from the photo in fig. 3. The scattering of the frosted glass reduces the luminance reflected in the specular direction, but outside the specular direction the luminance is increased by veiling glare.

Appearance of transmissive objects

Terminology

Reflective objects
Transmissive objects