Hal V. Engel schrieb:
X11 seems to have support for ICM profiles. I stumbled across it yesterday while researching this on the web and even looked at some of the man pages for it on my SuSE 9.1 box. There are about 43 ICM related X11 commands. I don't know if it works. And I am sure that no one is using it because no one even knows it exists.Yes, X11 does have some color management support (see e.g. http://www.stanford.edu/~lharcke/programming/Xcms), but my understanding it, that X11 color management is very limited, i.e. it seems to support only matrix/shaper for Displays, but is by far not a full-featured CMM, and it *IS NOT* based on ICC profiles, but X11-proprietary.
And it is also not application transpararent, but can only be used from applications which explicitly call the provided API functions.
However, basically the latter applies to Windows as well. Programs like Adobe Gamma also DO NOT provide full color management for applications which are not CM-aware. My understanding is, that Adobe Gamma just loads three 1D-Luts for the R, G and B channels from the profile's vcgt into the video driver to adjust gamma and to possibly alter the white point. Surely, this implicitly does affect all - even non CM-aware - applications, but they still don't get the whole monitor profile applied, but only the vcgt. See also below.
Best Regards, Gerhard
----- quoted from a previous posting to this list -----
This has been and still is a topic under hard discussion in many forums :-)
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
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.
Anyway, just my 2 cents.
Regards, Marti.
