Marti, > This has been and still is a topic under hard discussion in many forums :-) Oh? Where are they - I want to join in the fun. ;^) (just kidding)
> > Of course this approach has advantages, but to my understanding also > has serious problems. Let's resume first how these profiles works. > > A typical profile using vcgt is a "two step" beast. Fist step is applied on > computer startup. The profile loads the videocard with a compensation to > make the display behave as a perfect 2.2 (or anything else) gamma. > Ok so far. But this does not change phosphor primaries, nor whitepoint. > So, all non-color managed applications are still operating in the native > monitor space, only the gamma they "see" now is 2.2 The gamma tables (or *something*) does, or can, change the whitepoint.(colour temperature that the monitor will display for code 255,255,255 sent to the graphics driver) I'm not sure whether it's actually just the R, G, and B ramps, or whether there is another "whitepoint" memory location in the display adaptor, to set the overall "gain" of the three channels. Anyway, the ability to set the whitepoint can be verifed easily in Adobe Gamma - set a whitepoint to something as far off the hardware whitepoint as you can (using the "adjusted" mode), and watch your display change to that whitepoint as soon as your system starts. Naturally, it is better to set the whitepoint using the monitor's controls if they are available. > > Then comes the second part. To do compensation for white point and > primaries, a color savvy app still needs to use the profile. Just the profile > is assuming gamma of monitor as a perfect 2.2. At that point the effort > required by the color managed app is exactly same as the profile were not > touched the hardware ramps at all. > > Benefits? well, all non-color savvy apps does "see" a gamma of 2.2 But the > primaries and white point are still wrong. > Drawbacks? Setting the gamma > of videocard is hardly OS-dependent, so, lcms would not be portable if > doing so. And more importantly, The profile is doing adjusts on your > hardware, which many people probably don't want. I assume a profile is > a characterization of how a given display does behave, not a way to > configure the display. I'm not saying that the vcgt functionality should be at the top of your list of things to implement :), but I feel that it is quite useful, that's all. Your first comment (in your previous message) gave me the impression that you felt that the vcgt does more harm than good, but now I understand what your concerns are. Greg. ------------------------------------------------------- The SF.Net email is sponsored by EclipseCon 2004 Premiere Conference on Open Tools Development and Integration See the breadth of Eclipse activity. February 3-5 in Anaheim, CA. http://www.eclipsecon.org/osdn _______________________________________________ Lcms-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/lcms-user
