All colors on this color wheel should appear to have the same lightness and the same saturation, differing only by hue.
Hue in the HSB/HSL encodings of RGB
An image with the hues cyclically shifted in HSL space
The hues in this image of a painted bunting are cyclically rotated over time.

In color theory, hue is one of the main properties (called color appearance parameters) of a color, defined technically in the CIECAM02 model as "the degree to which a stimulus can be described as similar to or different from stimuli that are described as red, orange, yellow, green, blue, purple,"[1] which in certain theories of color vision are called unique hues.

Hue can typically be represented quantitatively by a single number, often corresponding to an angular position around a central or neutral point or axis on a color space coordinate diagram (such as a chromaticity diagram) or color wheel, or by its dominant wavelength or that of its complementary color. The other color appearance parameters are colorfulness, saturation (also known as intensity or chroma),[2] lightness, and brightness. Usually, colors with the same hue are distinguished with adjectives referring to their lightness or colorfulness, such as with "light blue", "pastel blue", "vivid blue", "cobalt blue". Exceptions include brown, which is a dark orange.[3]

In painting, a hue is a pure pigment—one without tint or shade (added white or black pigment, respectively).[4]

Hues are first processed in the brain in areas in the extended V4 called globs.[5][6]

  1. ^ Mark Fairchild, "Color Appearance Models: CIECAM02 and Beyond". Tutorial slides for IS&T/SID 12th Color Imaging Conference.
  2. ^ "Hue, Value, Saturation | learn". Archived from the original on 2017-06-30. Retrieved October 27, 2017.
  3. ^ C J Bartleson, "Brown". Color Research and Application, 1 : 4, pp. 181–191 (1976).
  4. ^ "The Color Wheel and Color Theory". Creative Curio. 2008-05-16. Archived from the original on 2011-07-05. Retrieved 2011-06-09.
  5. ^ Conway, BR; Moeller, S; Tsao, DY. (2007). "Specialized color modules in macaque extrastriate cortex" (PDF). Neuron. 56 (3): 560–73. doi:10.1016/j.neuron.2007.10.008. PMID 17988638. S2CID 11724926.
  6. ^ Conway, BR; Tsao, DY (2009). "Color-tuned neurons are spatially clustered according to color preference within alert macaque posterior inferior temporal cortex". Proceedings of the National Academy of Sciences of the United States of America. 106 (42): 18034–9. doi:10.1073/pnas.0810943106. PMC 2764907. PMID 19805195.