Re: ICC Profiles
The basis of ICC profiles is CIELab - a mathematically defined, objective color model based on observations of human color perception. Think of it as Esperanto for color (remember the "universal language").
An ICC profile contains a description of the colors achievable by a device, and ways to translate into and out of some variant of CIELab. So, if we go back to the language analogy, an ICC profile would go from say English to Esperanto and from Esperanto to English.
"How are they important?"
ICC profiles allow us to communicate color to one another in an objective manner.
That's a very short description. You might take a look at
www.color.org.
There are also some good books on the topic:
Principles of Color Management by Abhay Sharma
Color and Its Reproduction by Gary G. Field (GATF)
Real World Color Management by Fraser, Murphy, and Bunting
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