nVidia GeForce LUT

[Gregow]

I've been trying to find an answer to this, but there's seems to be very little information out there and different theories...

The question itself is rather simple:

If I set my GTX 970 to 10 bits per channel on DisplayPort, or 12 bits per channel on HDMI, do I get an 8 bit LUT with 10 or 12 bit precision? And, is there any dithering involved?

Let's assume we have an 8 bit display (with 10 bit LUT, if that should matter). So, no 10 bit output from the display (that's another ball game, and I believe nVidia has enabled 10-bit output for some applications on the GeForce cards).

I've seen some claims that nVidia is lagging way behind AMD here, by running 8 bits without dithering. With the current drivers however it seems GeForce cards can get 10 or 12 bit precision through DisplayPort or HDMI, though there's still no dithering used. I don't know how reliable that information is though.

Maybe someone here knows how it works?

 

[TheRyuu]

You might find some information in the madvr thread[1] over at doom9 although you'd have to search in it since it's quite long (find dates when they first enabled 10-bit output probably, driver 353.06).

There's also this thread[2] for 10-bit display support test which while the test itself probably doesn't matter for you the information in the post may, such as:

Since driver version 353.06 users can select bit depth in the Nvidia Control Panel on all systems.
If you can't see 10bit option in the CP, Nvidia will dither down to the bit depth selected if it is lower.

In other words, If you can't choose 10bit in nvidia CP and keep it on 8bit, when you run madVR in 10bit FSE, nvidia WILL Dither and you'll see smooth gradient, not true 10bit.
If you can select 10bit in Nvidia CP, the driver will NOT dither and sent true 10bit signal to your display.

I'm not sure if either of these are what you're looking for and I don't think I answered the question about how LUT's behave either but it may be a place to start. You may want to pose your question in the madvr thread[1] if you can't find anything there, they may be able to give a better answer if you don't find one here.

[1] http://forum.doom9.org/showthread.php?t=146228
[2] http://forum.doom9.org/showthread.php?t=172128

 

[Gregow]

Thank you! I haven't found a direct answer to my question, but there's still a lot of interesting Reading. And, it's certainly in the right direction. I'll try and post my question there and se if anyone knows the answer.

If you have a GeForce graphics card and a regular 8-bit display connected through HDMI or DisplayPort, perhaps you could check something for me? Do you have a 10-bit or 12-bit option in the nVidia control panel (found under the 'change resolution' tab)?

In case higher bit depths are available there even when connected to regular displays, then there's a fair chance the LUT can be calculated with higher precision and mapped to the 8-bit output. Which, in turn, would be good news for image quality.

I just replaced my old display connected through DVI. With the new display connected through DisplayPort I can't change the bit depth from 8-bits (it's an 8-bit display with 10-bit LUT). I haven't tried HDMI though, as I don't have a long enough cable.

 

[therealnickdanger]

I haven't done any testing with it, but I can confirm that the option exists.

I've got an older HDMI monitor connected to my GeForce on one of my machines and when I first plugged it in, it looked really washed out and dull. For some reason it had defaulted to 8-bit Limited RGB (16-235). So I went into the settings and changed it to proper RGB (0-255) and the blacks instantly improved (as they should), but then I noticed that I had the option to choose 10-bit or 12-bit color. Knowing that this old LCD was likely only 6-bit native, maybe 8-bit, I cranked it to 12-bit in the driver and the colors immediately looked richer. Is it accurate or objectively better? Likely not, but it looks subjectively better and I don't use it very much.

 

[Gregow]

Interesring. What kind of monitor is it?

I've tried both DP and HDMI now, and still only get 8bpc to choose from (the option isn't greyed out though, like it is with DVI-connection).

I noticed however that my display is only recognized as 'generic PnP display' in Windows. Perhaps it's a drivers issue. However there doesn't seem to be any drivers from the manufacturer available.

 

[therealnickdanger]

Interesring. What kind of monitor is it?

I've tried both DP and HDMI now, and still only get 8bpc to choose from (the option isn't greyed out though, like it is with DVI-connection).

I noticed however that my display is only recognized as 'generic PnP display' in Windows. Perhaps it's a drivers issue. However there doesn't seem to be any drivers from the manufacturer available.

It's just a 23" budget TN Acer I got years ago, I don't know the model number off hand. It is probably a driver issue. Windows always installs a specific Acer driver for this model whenever I connect it to a new machine. Can you get a driver specific to your display from the manufacturer?

 

[Gregow]

Thanks! I'm going to try a fresh install of Windows to see if that helps (I got a messy upgrade installation of Windows 10 so it's about time to fix it anyway.

I got a calling from Eizo (my monitor manufacturer) today. They suggested that I try DVI to seek if Windows recognizes the display. Unfortunately I don't have a dual-link cable.