MX-PEX1 (serv.man12). Fiery PEX1 Colour Reference Guide - Sharp Copying Equipment User Guide / Operation Manual. Page 74

This section introduces concepts that are basic to color theory. You will encounter some of 
these concepts (such as hue, saturation, and brightness) when you work with color in 
applications; others provide useful background information. Color is a complex topic, so 
consider this a starting point for experimentation and further research.

The human eye can see electromagnetic radiation at wavelengths between 400 nanometers 
(purplish blue) and 700 nanometers (red). This range is called the visible spectrum of light. 
We see pure 

 as intensely saturated or pure colors. Sunlight at midday, which we 

perceive as white or neutral light, is composed of light from across the visible spectrum in 
more or less equal proportions. Shining sunlight through a prism separates it into its spectral 
components, resulting in the familiar rainbow of colors illustrated in the following figure.

Like the sun, most light sources we encounter in our daily environment emit a mixture of 
light wavelengths, although the particular distribution of wavelengths can vary considerably. 
Light from a tungsten light bulb, for example, contains much less blue light than sunlight. 
Tungsten light appears white to the human eye, which, up to a point, can adjust to the 
different light sources. However, color objects appear different under tungsten light than they 
do in sunlight because of the different spectral makeup of the two light sources.

The mixture of light wavelengths emitted by a light source is reflected selectively by different 
objects. Different mixtures of reflected light appear as different colors. Some of these mixtures 
appear as relatively saturated colors, but most appear as grays or impure hues of a color.