L

L*
The lightness coordinate for the CIEL*a*b*, CIEL*u*v* and CIE94 colour difference formulas which converts the Y tristimulus value into a more visually linear scale.

Ladd-Franklin theory of colour vision

Lambert's law
When two filters, spectral transmissions T1 and T2 are placed in series the transmission of the combination is T1.T2 Defining optical density as:

LCH°
Used to define the position of a colour in space (i.e., CIEL*a*b*) in terms of its polar coordinated (lightmess, chroma and hue-angle) as opposed to rectangular coordinates.

Light

Light booth, light cabinet
An enclosed area with controlled lighting for viewing colours, often with a neutral grey background.

Lightfastness
The ability of a material to withstand colour change on exposure to light

Lightness

Line element

LLAB

Lovibond colour system

LUTCHI

Lumen

Luminance

Luminance factor
Luminance relative to that of a perfect white (perfect diffuser) identically illuminated. Calculated by L/L_p The luminance factor correlates with lightness, but not uniformly.

Luminescence

Lustre

Luther-Nyberg object colour solid

Lux