Apple Color 1.0 - Manual (Page 116)

116 Chapter 6 Monitoring
What Is a LUT?
Simply put, look up tables (LUTs) are precalculated sets of data that are used to adjust
the color of an image being displayed with the gamut and chromaticity of device A to
match how that image would look using the gamut and chromaticity of device B.
The gamut of a particular device represents the total range of colors that can be
displayed on that device. Some types of displays are capable of displaying a greater
range of colors than others. Furthermore, different video and film standards specify
different gamuts of color, such that colors that are easily represented by one imaging
medium are out of bounds for another. For example, film is capable of representing far
more color values than the broadcast video standard.
Chromaticity refers to the exact values a display uses to represent each of the three
primary colors. Different displays use different primary values; this can be seen on a
chromaticity diagram that plots the three primaries as points against a two-
dimensional graph representing hue and saturation within the visible spectrum. Since
all colors represented by a particular display are a mix of the three primaries, if the
three primary points vary from display to display, the entire gamut of color will shift.
While the chromaticity diagram shown above is useful for comparing displays on paper,
to truly represent the hue (color), saturation (intensity of color), and lightness
(luminance from black to white) that defines a complete gamut, you need to use a 3D
color space.