Converting between color spaces is a complicated business.
Suppose you want to convert your image into a CMYK one. Depending
on the type of printer, the type of ink and the type of paper you
are using you may require different amounts of Cyan, Magenta,
Yellow and Black inks to match the colors in your image.
What is needed is a standard approach to this kind of problem.
Eight major players in the industry founded the International Color Consortium (ICC) to do just
that. The ICC defines a standard file format for describing the
color profiles of monitors, scanners, cameras, printers - in fact
almost any device. Each profile describes how the device represents
color in a way that is independent of that device.
So when you take a picture with a digital camera and print it on
a color printer, the image is transformed from the color space
described in the camera color profile to the color space described
in the printer color profile. This process aims to ensure that the
colors in the original scene match those on the paper as closely as
You can find out more about the International Color Consortium