Colors are the basic elements of a painting. Gaining an intimate knowledge of the personalities of the colors you use is crucial in learning to paint. We tend to simply call paint a particular color, whether general such as “light blue”, more poetic such as “aquamarine blue”, or specific such as “ultramarine blue”. But in fact every color has three sides to its personality: hue, value, and chroma. A painter trying to mix a color on their palette to accurately match a color in their subject needs to consider all of these. If you don’t, you’re doomed to never get the color mixed correctly.
What is Hue?Hue is the easiest to understand: at its most basic, it’s artspeak for the actual color of a pigment or object. But the use of hue becomes more complicated when it comes to the names that paint manufacturers give their paint colors. This is because the term “hue” is used to indicate that a color is not made from the pigment(s) that were originally used for that paint, but modern equivalents that are either cheaper or more lightfast. Judging a hue is the first step in color mixing as it identifies what tube of paint to reach for.
What is Value?Value or tone is a measure of how light or dark a color is, without any consideration for its hue. Think of it as taking a black-and-white photo of a subject where you clearly see what’s in the photo but everything’s in grayscale.
The problem with a color’s value or tone is that how light or dark is seems is also influenced by what’s going on around it. What appears light in one circumstance, can appear darker in another circumstance, for instance when it’s surrounded by even lighter tones. (See Tone is Relative to Other Tones for an illustration of this, and a longer explanation.)