Hue
This term describes the characteristic of color that distinguishes blue from red from yellow. These hues are largely dependent on the dominant wavelength of light that is emitted or reflected from an object. For instance, the range of visible light is generally between Infrared Light and Ultraviolet Light. From the color spectrum, any pure hue can be mixed with white, black or gray to yield a tonal family.
Chromaticity
Often referred to as "colorfulness," chroma is the amount of identifiable hue in a color. A color with no hue is achromatic or monochromatic and will appear gray. For most colors, as the brightness increases, the chroma increases as well, except with the very light colors.
Saturation
Saturation, also known as "intensity", describes the strength of a color with respect to its value or lightness. What that means is a color's saturation is the degree to which it is different than gray at a given lightness. For instance, colors near middle gray are relatively unsaturated compared to brighter, more vibrant colors.
Value
The value or brightness of a color is based on the amount of light being given off by the color. The easiest way to remember this dimension of color is to visualize the "grayscale," which runs from black to white and contains all of the possible grays. The brighter the color is, the higher its value. So a royal purple has less value, emits less light, than a sky blue.
