Windows Vista has a new color-management/profiling format called Windows Color Systems. It purports to offer advanced color management and better results than the age-old (and forever dying) ICC/ICM color system. ICC has been buggy the whole way, with both political and technical issues plaguing its colorful history.
Windows Color Systems is a step in the right direction, but it comes at a very heavy price: Windows Vista no longer properly interfaces with ICC/ICM color profiles!
Anyone using the ATi Catalyst Control Center, BasicColor, ColorEye, Spyder, or any of dozen other color-management and gamma-correction programs available will have noticed the bug we’re talking about: once you lock your PC (winkey+L) the gamma LUT on your graphics card is reset.
ICC/ICM profiles have two different “parts” to them. The first is a color-correction section which “maps” the colors produced by the video card to match the correct color output as defined by your monitor. “Blue” on your monitor may be different from the “blue” on your mother’s – that’s what the monitor-calibration and gamma-correction software seeks to fix. Once you “regulate” the colors on your PC, you’re using the “real” blue, one that the color industry has reached a consensus over.
The second section of the ICC regulates the gamma output. In order to make certain colors match up, the gamma (more or less the amount of black/bright your display shows) is modified to tally-up with the correct settings. With properly-calibrated monitors, an image will display (almost) exactly the same – with the same hues, midtones, and shades; with the same brightness; and the same overall effect. Gamma plays a very important part in this, regulating the highly-varying brightness/contrast settings on monitors to produce the same image in the end.
With Windows Vista, when you first load an ICC profile, the correct color and gamma settings are applied. But when you lock the screen, log off, or do a bunch of other things, the gamma LUT is reset. The correct colors are still applied, but depending on your configuration your display might now be a garishly bright hue of green or blue!!
There is no fix, at least none that we can see. We’ve tried to apply the ICC profile to both the local account and the default system settings, we’ve disabled UAC and formatted and reformatted. We’ve tried it on nVidia and ATi, and it always happens: when you lock the PC, your gamma table is reset.
Microsoft has not yet acknowledged this issue (as a quick search for “gamma” or “ICC” in the Microsoft knowledge-base will reveal), but there is a workaround (though a poor one). The freeware DisplayProfile utility (donate to help cover hosting costs!) will show you a list of available ICC profiles and let you switch between them on the fly, but more importantly, it will also apply the gamma table settings as well.
DisplayProfile is a standalone executable. Just run it and select a profile other than the one you want to use, then switch back to the real profile in order to re-apply the gamma LUT settings. Just stick it in your quicklaunch toolbar, and whenever you unlock your PC run it to reset the gamma settings.
Hopefully Microsoft will address this issue with Windows Vista SP1 later this year. Until then, thank God for freeware!