On Thu, 2009-04-16 at 18:27 +0200, "Gerhard Fürnkranz" wrote: > In Calibration mode, the monitor uses its native (wide gamut) primaries, and > the luminance, white point chromaticity and gamma targets are established by > NCE (and eventually the resulting calibration is stored in the monitor). > > In Emulation mode, the XL20 attempts to emulate the characteritics of a > different monitor. When you set up the Emulation mode with NCE then you have > to supply the ICC profile for the (other) monitor which should be emulated by > the XL20, and a luminance target. I.e. the major difference between > Calibration and Emulation mode is, that in Emulation mode the monitor won't > use it's native primaries, but emulate different ones. > > sRGB and AdobeRGB mode are just special cases of Emulation mode, where the > XL20 emulates the sRGB color space or the AdobeRGB color space. > > > Finally, I presume all this works only under Windows > > (or MacOS), and not under Linux. > > No, not under Linux... > > You can of course calibrate the monitor once under Windows, and then use the > calibrated monitor subsequently under Linux. > > You possibly still need to fine-tune it under Linux with dispcal (using the > graphics card LUTs), since the given gamma target and gray balance are not > established by NCE too accurately (at last not on my XL20). The white point > target on the other hand is established by NCE pretty accurately (thus > dispcal w/o specifying any WP target should suffice). > Thanks for confirming what I thought and clarifying it further. I am still a bit unclear about just exactly what happens in the monitor. With the usual method using argyll, there is a vcgt tag which is loaded in the video card. I checked the default .icm file that came with the monitor and one I made using the Huey under Windows. (I did it in custom mode, which was presumably wrong, but that doesn't matter for what I say below). Neither of these had a vcgt tag. I presume this means that what would normally go in that tag is (semi-)permanently stored in the monitor and I don't get to see it. Presumably the two .icm files are meant to be used by Photoshop and other color aware applications in the usual way. Do I have that more or less right? If so, using argyll under Linux, assuming I can skip making the vcgt tag, I can produce a profile and be in business. By the way, The profiles appear to be matrix profiles. At one time, I understood exactly how they work, but I can't remember the function of the TRC part of the profile. As a mathematician, I have no problem with the matrix part. > > If indeed there is some way to load data under Linux > > directly into the monitor, I should know about it. Perhaps > > ddcontrol, mentioned by Kurt, can do that, but so far I > > haven't been able to get it to compile under Fedora 9 > > because of problems with the version of pciutils provided > > by Fedora. > > Don't waste your time, ddccontrol can't (at least not currently). > > I've already spent some efforts to trace NCE's I²C communication with the > monitor. I already managed to get a hex dump of the packets, but it seems not > to be trivial to interpret the data (although there seem to be not so many > different commands involved, when a calibration is carried out). > > Regards, > Gerhard >