Apple Color 1.5 - Manual (Page 154)

Color is represented on CRTs, LCD flat panels, video projectors, and film projectors using
very different technologies. If you show an identical test image on two different types of
displays—for example, a broadcast display and a video projector—you can guarantee
there will be a variation in color between the two. This variation may not be noticeable
to the average viewer, but as a colorist, you need a predictable viewing environment that
adheres to the standards required for your format, and to make sure that you aren’t driven
crazy by changes being requested as a result of someone’s viewing the program on a
display showing incorrect color.
There is also variation within a single category of device:
• CRT monitors from different manufacturers use different phosphor coatings.
• Digital projectors are available using many types of imaging systems.
• Projected film is output using a variety of printing methods and film stocks.
All these variables inevitably result in significant color variation for any image going from
one viewing environment to another. One solution to this is calibration using LUTs.
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.
154 Chapter 6 Monitoring Your Project