> Right, but since it was Apple who created this tag, I think that > how they interpret it is what counts. Hm, I'm tempted to say "yes" - but: there are a bunch of other loaders that count as well - Logo Calibration Loader, Monaco thing, Spyder ProfileChooser, WindowsXP Color Control Panel, xcalib, dispwin, ... If I have the time I'm willing to find out, how they all behave - most of them are "professional" and widespread. Unfortunately I don't have access to all of them - so if anybody's having one of these loaders, please extend Frederic's sheet :-) Yesterday I tried the XP color control panel: It behaves like xcalib. >> The ramp is then created from the gamma values rGamma, rMax and rMin like >> this: >> >> for(j=0; j<nEntries;j++) >> { >> ramp[j] = 65536.0 * >> pow (j * (rMax - rMin) / nEntries, rGamma * SYSTEM_GAMMA) >> + rMin); >> } >> >> I think xcalib's behaviour is correct - at least if the >> result is compared to other calibration loaders like the WindowsXP >> color panel, ... > According to Apple documentation, this isn't how it works. > See <http://developer.apple.com/technotes/tn/pdf/tn2007.pdf> page 8/9: > Gamma values must be greater than 0.0. > Specify a value of (1.0 / 1.6) to get an antigamma of 1.6. > Min values must be greater than or equal to 0.0 and less than 1.0. > Max values must be greater than 0.0 and less than or equal to 1.0. > Returns kCGSRangeCheck error if the values are out of range or > max is greater than or equal to Min. > Values are computed by sampling a function for a range of indices from 0 > through 1: > value = Min + ((Max - Min) * pow(index, Gamma)) > The resulting values are converted to a machine specific format and loaded > into the hardware. That doesn't differ much from my formula above - besides the system gamma that I added. I know that I once checked with a Mac - but this was (afaik) xcalib 0.1 which didn't use the system gamma and therfore behaved like dispwin. I know that I changed this when I saw all the Win32 loaders (incl. AdobeGamma? ) - and then the 2.2 thing came in. > Checking on my Apple laptop, the "Gamma 2.2" profile Frédéric attached behaves > exactly the same with the Apple profile calibration loader as diswin, > brightening the screen considerably, so I conclude that the WindowsXP loader > is faulty, and dispwin is correct. Hm, maybe it's safe for both dispwin and xcalib to add a parameter for a gamma-nominator/mulitplier or something like this. But still I'm interested how all the other loaders work and will do some tests. Stefan -- mailto:color@xxxxxxxxx