Monitor Look Up Table - Double Profililng?

On my NEC Spectraview Calibrated P221W:

I understand the adjustments are uploaded to the monitor  internal color look up tables in EPROM. But it also produces a monitor color profile for the graphics card setup in Windows.

I have Win set to load the NEC profile produced by Spectraview.

With both the monitor look up table and the profile loaded in Win, is that correct or am I getting double profiling here. I do not see any disconcerting mismatch on prints but I thought I'd ask.

Do not set Windows to load the monitor calibration. It's either a do-nothing operation at best, or a mistake at worst.

Assuming Windows could read & process the LUT info from the Spectraview ICC profile (which I'm guessing it may not actually be able to do), it would load that info to the video card's 8-bit LUT. That's all that Windows is capable of doing. But you don't need Windows to do this by definition, because Spectraview is loading that info straight into the monitor's higher bit depth internal LUT.

Windows is loading the ICC profile file (NECxxxxxx.icc) created by spectraview into the graphics card port 2 setup I assume during windows startup for the NEC's port 2, not reading the monitor look up table. That was loaded into the monitor when calibrated using Spectraview or running the Spectraview background service (which I only run on demand).

The NEC is my second monitor used for image editing and printing adjustments.

I am using the later Win XP color manager BTW supposedly which works around the Win XP individual profile per port problem.

Knowing that it's a 2-monitor setup may change the response. What video card have you got? That's an important detail... you need to know whether you're playing with 2 separate video card LUT's (one per video port), or only 1 (which is the most common -- a single LUT shared across the ports).

I understand about the separate or single card LUT tables but for this question let us consider a single LUT on board monitor and single port used:

If on starting Win it uses an icc profile applies to the card LUT and the monitor has its calibration in its on board LUT will both be effective and conflict?

Now if the icc profile created by Spectraview sets up the card to as standard expecting the correction to be in the monitor LUT then I don't see a conflict.

I'm not the best communicator.

Okay, so we're back to a one monitor case. In which case, as I stated above, yes it will be a conflict if the calibration data contained in the ICC profile is loaded by Windows into the video card LUT, while it has already been loaded by Spectraview into the monitor's internal LUT. You do not want to double-load the LUT data because it adjusts white point, black point, curves, etc. Doing this in 8-bit space in the video card, followed by the monitor doing it again at a higher bit depth in its internal LUT, would be an error. Similar to double-profiling during printing.

The monitor ICC profile contains a single set of calibration data; see the tag called VCGT (video card gamma table). The actual work is done by software applets that take the data from the VCGT tag, and apply it in the methods they know how to do. If you run 2 calibration loaders, they'll both try to do their job without any reference to each other. The Spectraview calibration loader definitely will do its thing, which is load the VCGT info into the monitor LUT. But Spectraview expects the video card to be linear, i.e. not having any calibration adjustments applied to it, because Spectraview believes it is in control of calibration on the system and it will program the monitor LUT not the video card LUT.

Meanwhile the Windows calibration loader knows nothing about Spectraview; it will try to load the VCGT info into the video card LUT. The Spectraview calibration loader typically fires only once, while the Windows calibration loader may fire off many times based on different things that Windows does from time to time. If the Windows calibration loader modifies the video card at all, it will do so most likely after Spectraview has set the monitor to what it thinks is correct. Windows will screw it up by de-linearizing the video output before it reaches the monitor.

The best case situation you could hope for would be that Windows can't actually read the Spectraview-generated VCGT data, and doesn't actually load anything into the video card. But either way, in this situation, definitely don't set Windows to load the calibration data. It's either pointless or an actual mistake... there's no reason to do it.

. . . so my question remains:

Does the .icc profile produced by Spectravue set the card to linear operation (for Windows loading - it needs something) so as not to interfere with the monitor LUT produced profile.

The ICC profile does not "set" anything. It merely contains calibration data in the VCGT tag that can be loaded into a single LUT somewhere. The thing that actually does the LUT loading is a calibration loader utility. Each calibration loader utility has a single purpose -- to load data from the VCGT tag into the LUT that it knows how to access.

Since Spectraview created the ICC profile, the VCGT tag contains only the information needed to load the LUT within the NEC monitor itself. The main Spectraview application will most likely reset the video card into a linear state at the start of a calibration run, to ensure that no odd video settings are corrupting the calibration & profile readings. However that linear video card calibration info is not encoded into the Spectraview ICC profile... there's nowhere to put it. The VCGT tag will contain only the data for the NEC monitor LUT.

If Windows or any other software messes with the video card on top of what Spectraview has done, it will screw up the display, essentially a case of double profiling (technically, double calibration). As I mentioned above, the NEC calibration loader will run at most once (to load the NEC monitor LUT). The Windows calibration loader may run any number of times as Windows changes the video state for various reasons.

So my recommendation remains the same as stated from the beginning -- do not configure Windows to load calibration data if you're running a NEC Spectraview monitor. Let Spectraview take care of it. Configuring Windows to load calibration data on top of Spectraview will do nothing in the best case (if Windows can't read the NEC LUT data), or mess up the calibration in the worst case. Just don't do it.

As an aside, it seems you have something you're trying to accomplish. Perhaps jump forward in the sequence and just describe what you're trying to do so we can address that rather than whatever these intermediate things are about. E.g. are you trying to figure out how to have 2 calibrated & profiled monitors on your PC, with one of them being the NEC Spectraview, and the other being something else?

I just have a feeling that the current line of Q&A isn't taking you in the direction of whatever your goal really is...

I use three post processing applications applications where you specify the monitor profile to be used:

QImage Ultimate
Canon DPP
and on occasion Corel Paintshop Pro.

I also have a plug in added to PSE 10 that requests a monitor profile for soft proofing. By itself PSE 10 does not concern itself with the monitor profile. I assume PSE without bringing up the soft proof plug-in leaves the monitor profile to Windows.

Most of my photo image editing is done on the NEC on port two of the video card. My "general" Viewsonic VP2165 has a ColorMunki Photo derived (sRGB) profile set up on Win for Port 1 (it matched the factory provided profile except for luminance) which I reduced to 95 nits for print proofing.

So, in the NVidea/Win setup for port 2 (NEC) what do I enter for the .icc profile to avoid conflict with the NEC LUT which was set during Spectraview calibration and is non volatile?

What specific video card?

NVidia GeForce 6800 GT (Yes it is old.) DXDIAG shows its apparent single LUT is now set with the NEC icc profile created by Spectraview.

I should note that after I enable the NEC (and let it warm up - fl backlight- and dual view I make the NEC display on port 2 hot by clicking within an app on it, open Spectraview, and toggle the Target profile to insure its LUT is updated before editing on it. I have two targets for it with different luminance values. I do not use the NEC ambient light compensation since I have controlled lighting. It is the same lighting I use for each calibration.

I am forced right now to use use an AGP card. Long story why I have not replaced the mobo.

FYI, I haven't abandoned this discussion, I've just been overloaded with other stuff. I'll be coming back to the topic...