Munsell Color Order System

The Munsell Color Order System, commonly called the Munsell Color System, is a color space for describing color of surfaces. It uses an irregular 3-dimensional color space. The dimensions are hue, represented as a circle, value, along the central axis, and chroma, represented as distance from the axis. Changes in each dimension are intended to be perceptually equal within the dimension, so that an increase of chroma from 3 to 4 is perceived as the same difference as an increase from 7 to 8. As a result, the color space is not geometrically regular, unlike most color systems developed previously.

The Munsell system has five primary hues: Purple, Blue, Green, Yellow, and Red, and five secondary hues, equidistant between the primaries.

A color is described using the notation H V/C, for Hue, Value, and Chroma. Hue is notated with a number and the letter(s) representing the primary or secondary color being represented, while value and chroma are notated purely with numbers. For example, a vivid orange may be 5RY 7/12. Numbers for hue range from 0 to 10 at each primary or secondary color, and increase in the direction from red to yellow. The primary colors use the initial letter of the color name, while the secondary colors use the initial letters of the two primary colors nearest, thus RY for orange. The letter N is used for pure grays (including black and white). Value is measured from 0 (pure black) to 10 (pure white), though a value of slightly higher than 9 is the highest practically obtainable. Chroma is measured in equal perceptual steps. In the original Munsell system, 10 was the highest chroma possible, but advances in pigmenting technologies have made possible materials with chroma ranging over 20, and fluorescent materials can have chroma greater than 30.

The Munsell system was developed by Albert H. Munsell, an American artist and researcher. The first version of the Munsell system was published in 1915, in the 15-page Atlas of the Munsell Color System. In 1929, the Munsell Book of Color was published, updating the system. The update had 20 pages of different hues, with about 20 samples on each page of varying value and chroma. The system was updated again in 1943, with an extensive recalibration. The 1943 update is the one most commonly used. The Munsell Color Order System has been adopted in various national standards: American National Standards Institute ANSI Z138.2, Japanese Industrial Standard for Color JIS Z872, German Standard Color System DIN 6164, and others.