H

Haploscopic matching

Haze (in reflection)

Haze (in transmission)

Helmholtz-Kohlrausch effect

Hemisperical optical measuring system

Hering opponent colour theory

Heterochromatic photometry

Hickethier colour system

Hiding power

Holmgren wool test
For the testing of colour blindness. A number of small varicolored skeins of wool are spread out before an observer who is required to select those resembling three larger skeins, a red, green and rose.

Hue
That attribute of the visual sensation which allows a colour to be described with names such as red, yellow, green, blue etc.

Hue angle
In colour spaces such as CIELab, CIELuv, ANLAB etc. The hue-angle is the polar coordinate expressed on a 0 - 360° scale, and may be calculated as follows:

Find the angle (theta) whose tangent is (b/a) (ignoring the sign of a and b) h° then depends on these signs as follows:

Hurvich-Jameson colour-vision model

Hydrochromic
A colour that changes when the moisture content or relative humidity varies.