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Profile Gamma Tagger

SmartNote: 1027
Type: Utility
ColorGeek factor:
Monitor profiles depend on the calibration of the display system (graphics card and monitor) in order to work correctly.

After your monitor calibration system has completed its job, the video graphics card LUT's contain calibration curves. When the computer is shut down or restarted, these curves are lost and must be replaced in order for the calibration to persist.

In ColorSync 2.5 and later, Apple created the 'vcgt' (Video Card Gamma Type) tag which can contain graphics card curves. Technically the 'vcgt' tag is not part of the ICC specification but it is very valuable in "marrying" the calibration with the profile. When the profile is selected in the Monitors control panel (Display system preference pane in Mac OSX), the contents of the vcgt tag are loaded into the graphics card and the display system is returned to its original state.

Most monitor profiling applications have been updated to create these vcgt tags but for those that have not, the Profile Gamma Tagger utility from Apple will pull the curves out of the graphics card and embed them into the profile in a vcgt tag.

Just drop a profile onto this utility, select the curves to embed and that's it. There is a Readme file included for more information. This utility is from the ColorSync SDK.

Special thanks to Bruce Lindbloom for finding a bug in the code and recompiling this utility for PowerPC. Great guy, good color.

Download Profile Gamma Tagger

(10K - Mac only)