Chart C from Munsell's 1915 Atlas: a vertical gray axis from black to white inside a circle, with painted branches of different lengths: yellow to the right near the top, green and blue to the left near the middle, red to the right at middle height and longest, and purple to the right below it.

Concept · Foundations

Munsell's System

Devised by Albert Munsell, this system places each color on three scales. Hue runs around a circle, value up a gray axis from black (0) to white (10), and chroma outward from that axis.

A notation such as 5R 4/14 reads hue, then value over chroma: a strong red a little darker than middle gray. The circle rests on five principal hues, not the painter's three. Munsell compared a chart that ignores chroma to 'a map of Switzerland with the mountains left out.'

On his 1915 chart, red reaches ten steps from the axis at value 4; blue, at the same value, only six.
Every hue shares the one gray axis, so colors of any hue can be compared by value alone.
Chroma has no fixed end; Munsell expected branches to lengthen as stronger pigments appeared.

Image: Smithsonian Libraries via Internet Archive · Public domain