A uniform colour space (UCS) is a colour model that seeks to make the colour-making attributes perceptually uniform, that is identical spatial distance between two colours in a color space equals identical amount of percieved Colour Difference.

Tolerance

It asks the question, what is the set of colours which are acceptably close to a given reference?

If distance measures are perceptually uniform throughout the gamut, then the set of points which are imperceptibly/acceptably close to a given reference are simply the set of points whose distance to the reference is less than the just-noticable-difference (JND).

The differences of sizes of tolerance contours signify non-uniformity of distance measures across the gamut, and that is what motivated the creation of CIELAB and CIELUV

A CAM under a fixed viewing condition results in a UCS; a UCS with a modelling of variable viewing conditions results in a CAM. A UCS without such modelling can also be a rudimentary CAM.

Attempts

CIE 1960 UCS
CIEUVW
CIELUV
CIELAB
HSLuv
Newer Models
- IPT colour space of 1998 is uniform after cylindrical transform
- OKLab's CAM(CAM16)/OKLCH is uniform after cylindrical transformation.

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