Varieties of the color red may differ in hue, chroma (also called saturation, intensity, or colorfulness) or lightness (or value, tone, or brightness), or in two or three of these qualities. Variations in value are also called tints and shades, a tint being a red or other hue mixed with white, a shade being mixed with black. A large selection of these various colors is shown below.
Pigment red is the color red that is achieved by mixing process (printer’s) magenta and process (printer’s) yellow in equal proportions.
Psychedelic art made people used to brighter colors of red, and pigment colors or colored pencils called “true red” are produced by mixing pigment red with a tiny amount of white. The result approximates (with much less brightness than is possible on a computer screen) the electric red shown above.
The color defined as red in the Munsell color system (Munsell 5R) is shown at right. The Munsell color system is a color space that specifies colors based on three color dimensions: hue, value (lightness), and chroma (color purity), spaced uniformly in three dimensions in the elongated oval at an angle shaped Munsell color solid according to the logarithmic scale which governs human perception. In order for all the colors to be spaced uniformly, it was found necessary to use a color wheel with five primary colors—red, yellow, green, blue, and purple.
The color defined as red in the NCS or Natural Color System is shown at right (NCS 1080-R). The Natural Color System is a color system based on the four unique hues or psychological primary colors red, yellow, green, and blue. The NCS is based on the opponent process theory of vision. The Natural Color System is widely used in Scandinavia.