Max,
With Windows Vista (or at least with Ultimate, which I’m using), Windows will load unique profiles for each monitor you’re using, so it appears that a graphics card with dual LUTs is not required. But, to answer your question, most ATI cards natively provide dual LUTs where most nVidia cards do not. That might not be true of nVidia’s workstation-class cards (Quadro), but I’m not familiar with them. In my case, I’m running an nVidia 7600GT with dual DVI out, with one connected via a DVI/VDA adapter to my Iiyama CRT while the primary DVI drives my BenQ LCD monitor. In the Windows Color Management panel, each monitor has its own calibrated profile and I’ve verified the assignments are loading correctly, using GretagMcBeth’s Display Profile tool.
So, for what I can tell, it doesn’t really matter whether you go with ATI or nVida for Windows Vista…just go with whichever you prefer.
Regards,
Daryl
If you want to calibrate 2 monitor your card needs 2 LUTs. Don`t mix that up with the possibility to assign 2 ICC profiles. The LUT is required to bring your monitor to a "standard" concerning colortemperature, gamma and so on. The ICC profile that is then generated only "describes" the result of the calibration. So you need both: Two Luts and the ability to assign 2 profiles. Concerning nvidia cards I can tell you that every card on the market has 2 separate LUTs (as long as it has two outputs, of course). Even the Geforce 4 (now we have Geforce 8) had 2 Luts! The possibility to assign 2 ICCs is a different story and depends on the driver and OS. With Vista it should be no problem, but nvidia cards were not able to assign 2 ICCs under XP, although they had 2 independent Luts.
Stefan
Stefan,
That’s interesting to read, as I’ve always heard just the opposite about nVidia cards, and could have sworn I read something similar to that on their website, about how most only have 1 LUT. Right or wrong I don’t know, but I’ve also read that if a card has dual LUTs, it will show up in the Display Manager as two separate graphics cards, and I have seen that to be true with an ATI card I’ve got, yet not true of my nVidia.
Under XP, I successfully use the Windows Color applet to load independent profiles for my monitors, and that sure seems to find my system behaving as if it has two LUTs. The Vista Color Management panel is a beefed-up version of that it seems.
Mind you, I’m not debating what you say is true, but only that I’ve read differently and would welcome any links directing me to facts. At present, the only thing I find on the nVidia site comes from a search of their FAQ/Knowlege Base, where I found only one question on the topic:
Question:
Does NVIDIA support (LUT) Look Up Tables for display calibration using ICC profiles?
Answer:
Yes, you can load an ICC profile for the primary/single monitors, and use a professional publishing application to perform color matching based on information in the ICC profiles. To use two ICC profiles for separate monitors, you will need an additional graphics card installed on your PC, one for each additional monitor.
Of course, as you see, the neither the question nor answer ask specifically about Dual LUTs, but as the topic was updated in May ’07, and the nVidia reply states the need for an additional graphics card for each monitor, that suggests there is only one LUT per card…although admittedly, they fail to mention dual-head cards. In short, this question doesn’t really address the details we’re looking for.
Regards,
Daryl
Daryl, I cannot give you any links, because I don`t have any, that I could find easily. I gave the Windows color applet a try a few months ago. And while it was able to load 2 different LUts witha nvidia card, it was not able to use individual ICC profiles for the 2 displays.
There is an easy way to proove that nvidia cards have two LUTs: Just go to the driver panel ant there to "color correction". As soon as you manipulate the sliders your monitor gets brighter, darker , greener, more contrasty…..whatever you want. Whatever monitor you have chosen before is going to react and you can apply individual setings for both monitors. That can only be done with individual LUTs. It works with a beta version of Colorvision`s "Optical" as well. Those sliders in the driver have NOTHING to do with ICC profiles. They affect the LUTs…..both of them. Unfortunately nvidia`s drivers (at least under XP) did not let you use individual ICC profiles. I know ATI DID let you. If the display manager shows 2 cards that only means that you can use 2 individual ICCs. Has nothing to do with the LUTs.
nvidia writes "To use two ICC profiles for separate monitors, you will need an additional graphics card installed on your PC, one for each additional monitor."
That was true for XP as I mentioned above(although they had 2 LUTs). I don`t know ( and don`t hope so), that it`s still true for Vista. Stefan
Stefan,
Thanks…I’ll check out using the graphics card driver to individually adjust each monitor’s color to confirm what you’re saying. It does sound reasonable. I’ve never used those color controls since I always got the best results doing the color adjustments to my monitors via their controls in the process of doing a calibration, while leaving the driver’s color controls alone.
Daryl
I just asked ATI if my card supported independant LUTs, their answer was that NO ATI card has any hardware LUTs. Yikes! Was that a stupid answer or what. ATI has no info on this matter on their site, you would think that this would be important information to provide. I guess they just assume this. Matrox, on the other hand, was very clear about this.
Thanks Daryl, my display adapter (FireGL5200) appears as two separate entries in the device manager and confirms what I thought.
Well, this is all an interesting "re-education" for me. Indeed, as Stefan said, I can independently adjust the colors of my two monitors on my nVidia 7600GT card. And, that would certainly seem to indicate two separate LUTs are being maintained. I had always thought that if one had two separately maintained monitor profiles, then they also had two LUTs, but I can see where that isn’t necessarily the case.
In fact, I’m seeing now that while Vista does allow me to defined two monitor profiles and they are correctly reported as I sweep the DisplayProfile utility back and forth between the monitors, there is a difference in the behavior from what I see in WinXP. Namely, the profiles reported by DisplayProfile are correct at all times, whereas it seemed under WindowsXP that I’d have to sometimes toggle the profiles for each monitor before they’d be correctly indicated. So, overall I’d say that’s points scored for Vista in offering better color control for your monitors.
Regards,
Daryl
Daryl, I also don`t really use those sliders, since they are useless for calibration. But it`s a way to examine wether the LUTs work.
I.D., ATI must be kidding. Just do the same test that Daryl did and you will see that you have 2 Luts. Although the sliders are on a different location somewhere in the driver. Just look for contrast, brightness or color- sliders.
BTW. if you want to calibrate 2 monitors you must be sure that your calibration software has the capability to access the 2 LUTs. That`s not always the case especially with older software.
Stefan
Stefan: Using Monaco EZColor with an OPTIXXR calibrator. Everything is skippy. The software supports dual LUTs and has a small utility for checking.
As for the ATI guy (level 3 tech support), I explained that the card would have to have at least one hardware LUT, my question was whether it has two. AMD guy, no doubt.
There is also an update to EZColor, there is a 64-bit driver for the calibrator. Cool, now I need to get the new RAM (still waiting) and get the new VISTA 64 system up and running.
I also use EZColor, including the update for Vista, but while it can be used to calibrate either monitor, the gamma loader will only load a single profile. That is why I switched to using the Windows Color applet for XP and rely upon Vista’s Color Management tool for loading the separate profiles when I’ve booted to Vista.
ID, what is the Monaco "small utility" you’re referring to for checking the dual LUTs? I don’t see anything installed with the application unless perhaps you found it as a seaparately-provided utility from Monaco at the time. It may be very similar (or the same?) as the DisplayProfile utility I downloaded from GretagMacbeth.
Regards,
Daryl
Thanks ID….a rather basic tool, but I guess it tells you all you need to know. It would be great if dragging it to a 2nd monitor and doing another test could indicate whether a 2nd LUT is available.
And if you’re not familiar with DisplayProfile, another stand-alone app for checking what profiles are loaded and changing them/reloading the gamma on-the-fly, here’s a link for it: <
http://www.gretagmacbeth.com/getfile?send=1&id=8712>
Daryl
Daryl: I just dragged the LUT tool to the second monitor where it worked. I thought it would be correct in that you can profile two monitors by dragging the EZcolor app window to the second monitor.
ID, I wasn’t very clear in what I said about that LUT Tester. While it does work on either of my monitors, it affects them both simultaneously in the same way, making it hard to know if that means there is a single LUT affecting both, or two LUTs with each independently affecting a single output channel but in the same way. I’d have liked to seen perhaps two separate color patches where both would change only if 2 LUTs were present. Still, it’s a useful tool for a quick check.
Daryl
