From an article in The Luminous Landscape by Alain Briot:

"In order to create a specific color palette for a photograph, colors need to

be organized. This is done by using one of several color arrangements.

These different color arrangements are called Color Harmonies. They are

called harmonies because the goal of these arrangements is to create

harmonious color palettes."

The three variables of color

Color is influenced by three variables: hue, saturation and luminosity. To create a specific color harmony, all three variables of color need to be modified. This is done in the software, either in the raw converter or, for a higher level of control, using layers in Photoshop.

Here is a short description of the three variables of color:

A – Hue

Hue refers to the name of a color. For example blue, red, yellow, etc.

B – Saturation

Saturation, which is also called chroma it is the intensity of a color. High saturation colors are bright and colorful while low saturation colors are less colorful and appear dull.

C – Luminosity

Luminosity, which is also referred to as value, is the lightness or the darkness of a color. Any color can be made lighter or darker. In painting this is achieved by adding black or white to a color. In photography it is achieved by increasing or lowering the exposure of the image either in the camera or in the software. In a photograph areas that receive a lot of exposure are more luminous than areas which received little exposure

Color Wheel

Complementary Color Harmony