The reflection of light can be roughly categorized into two types of reflection. Specular reflection is defined as light reflected from a smooth surface at a definite angle, whereas diffuse reflection is produced by rough surfaces that tend to reflect light in all directions (as illustrated in Figure 3). There are far more occurrences of diffuse reflection than specular reflection in our everyday environment.
To visualize the differences between specular and diffuse reflection, consider two very different surfaces: a smooth mirror and a rough reddish surface. The mirror reflects all of the components of white light (such as red, green, and blue wavelengths) almost equally and the reflected specular light follows a trajectory having the same angle from the normal as the incident light. The rough reddish surface, however, does not reflect all wavelengths because it absorbs most of the blue and green components, and reflects the red light. Also, the diffuse light that is reflected from the rough surface is scattered in all directions.
