ColorSync
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ColorSync is Apple's color management API for the Mac OS and Mac OS X.
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[edit] Version History
Apple developed the original 1.0 version of ColorSync as a Mac-only architecture. Later, Apple co-founded the International Color Consortium to develop a cross-platform profile format which became part of ColorSync 2.0. Apple, with the help of Adobe had ported ColorSync 2.0 and its SDK to Microsoft Windows. With ColorSync 3.0, the Windows version which was initially planned was discontinued. ColorSync 4.0 is the latest version, introduced in Mac OS X 10.1.
[edit] Overview
Human color perception is an incredibly complex and subtile process, and different devices have widely different color gamuts or ranges of color they can handle. To deal with these issues, ColorSync provides several different methods of doing color matching. For instance, perceptual matching tries to preserve as closely as possible the relative relationships between colors, even if all the colors must be systematically distorted in order to get them to fit within the gamut of the destination device. Because the human eye is more sensitive to color differences rather than absolute colors, this method tends to produce the best-looking results, subjectively speaking, for many common uses, but there are other methods that work better in some cases.
[edit] Profiles and color spaces
In ColorSync, the reference for defining colors is CIE XYZ space. All image input and output devices (scanners, printers, displays) have to be calibrated by providing a profile which define how their color information is to be interpreted relative to XYZ color space. This profile might be provided by the device manufacturer, but for better-quality results, it might be generated by performing actual measurements on the device with a colorimeter.
Thus, when an image is scanned on a scanner, the image file will include a copy of the scanner's profile to characterize the meaning of its color information. Then when the image is sent to an output device, a matching process converts the color information at the time of rendering from the source profile (that attached to the image) to the destination profile (that attached to the output device) so that the resulting colors print or display as closely as possible to the original image.
