Setting Nvidia to full range RGB

I frequently read that an HDTV is expecting 16-235 color space and am curious why some people use 0-255 for their HTPC & some use 16-235.

My HDTV will display blacker-than-black. However it is set not to show B-T-B when adjusted using a calibration disc in my Blu-ray player or a test pattern from a recording I captured with my satellite DVR. The TV has only one HDMI input so there are no variables in that regard.

My HTPC is set to send 16-235. If I play a standard DVD calibration disc or one with the THX optimizer in the Blu-ray player or the HTPC the black levels look the same. In a way I feel like I'm being cheated for using only 16-235, yet there is no perceivable difference in picture quality. I'm presuming this is because the TV is calibrated for hopefully the proper black level.

What is the advantage of sending out 0-255 color space?

Less compression of the colors.

Won't the TV cutoff or crush black levels below 16 since it is calibrated to not display B-T-B?

Maybe your TV needs to be re-calibrated?

I get very deep blacks and vibrant but natural color using 0-255.

The best way I have found to set 0-255 with Nvidia is to edit the .inf file during installation. It really only takes a few minutes to do it and then all resolutions will output 0-255. Even with out doing this custom resolutions will be 0-255. Another reason for doing this is if you are using MADVR it works best with everything at 0-255.

Run the driver installation file to the point where the file contents are extracted. Then cancel the rest of the installation.

Go to the folder where the files contents were extracted to.

Search for the file nv_disp.inf and open it.

Search for the section [nv_miscBase_addreg__01]

Under this section add the registry value:
HKR,,SetDefaultFullRGBRangeOnHDMI,%REG_DWORD%,1

Repeat this step for [nv_miscBase_addreg__02] and [nv_miscBase_addreg__03] and so on until all [nv_miscBase_addreg__xx" have the above registry value.

Save this .inf with the changes.

Run the setup.exe file in this folder to install the driver with the modified .inf. Each time you reload a driver, you will need to repeat this process.

I went over the TV calibration several times using the AVSHD 709 calibration software/DVD in my Blu-ray player. I also used an Avia standard DVD calibration disc in the Blu-ray player & had the same results. All the instructions say to adjust the TV so that you do not see B-T-B, which is what I did. Playing the Avia disc in the HTPC shows the same black levels & I have the Catalyst Control Center set to the YCbCr 4:4:4 Pixel Format which is a limited color space setting. IOW the HTPC is outputting only 16-235 yet it looks the same as the Blu-ray player which can output 0-255. That seems to make sense because the TV is calibrated to not display B-T-B.

I'm not trying to be argumentative, but I thought TV safe colors were 16-235 which is why calibration discs say to adjust the TV so that B-T-B is not displayed. I can adjust my TV so that B-T-B test patterns are visible, but according to any of the instructions this is wrong. What am I missing here?

Yes you need to do it with each new driver install, but really that should not be that often if everything is working. So far the only thing i have accomplished by updating my Nvidia drivers is the headache of recreating a custom resolution for 23.967 which I usually can get very close!

I think I need to look into this a bit more. Although Live/Recorded TV looks fantastic, mkv BR rips do come through a bit too dark. This may be my issue. For some reason I thought setting it for 0-255 in MadVR was all I needed to do but if I make these changes as are being suggested I fear that Live/Recoded TV playback will be too bright. Am I correct in this assumption?

Thank you. I will take a further look at that specifically. I have a "Recorded TV" strip in MB for wtv recordings. Just need to find one that is copy freely and check it out.

You have to have your display settings match so for anything other whats output from MAdVR the output levels will be 16-235 and your TV needs to be set for that, If you are outputting from MadVR with 0-255 set then you need to set your TV to Expanded or whatever term they use. You would ideally use a separate calibration for each, luckily my ESPON allows this so for HTPC I have a memory setting for Expanded and say for my directv it is a different memory setting for Normal.


Yes correct without modifying the install file or registry if you create a custom resolution then when set to that custom resolution it will be 0-255. I just find it easier for calibration purposes to do the install file modification that way any resolution is output properly (Bluray/DVD/Etc..)

I set MadVR to 16-235 last night and the picture is less dark for sure. Maybe I'll leave it this way and leave the card alone because Live/Recorded TV has the proper contrast but I will continue to adjust it.

According to several things I’ve read WMC uses 16-235 color space. This was no problem when I used Intel integrated graphics. But then I added an HD 6450 video card which has settings for Full & Limited Pixel Formats along with Full & Limited Dynamic Range.

If I use one of the YCbCr or the RGB Studio (Limited RGB) Pixel Formats in Catalyst Control Center it also converts the video to 16-235. This gave me washed out grays because both CCC and WMC were converting to 16-235 & resulting in a double conversion.

I could use the other RGB Pixel Format which is called PC Standard (Full RGB). But this caused crushed blacks when using WMP or MPC-HC. You would think WMC & WMP would perform the same but they don’t. WMC uses 16-235 color & WMP uses 0-255.

Here’s a lengthy thread about black levels and WMC. IIRC it also discusses Nvidia settings so it is appropriate to mention here.
http://experts.windows.com/frms/windows_entertainment_and_connected_home/f/114/p/59322/278264.aspx?PageIndex=1

I did the registry hack as mentioned in the above link. This forces WMC to use 0-255 which makes it match WMP & MPC-HC. When used with one of the 16-235 video Pixel Format settings in CCC all my HTPC players match the black levels of the Blu-ray player. Since the Blu-ray player does not have an adjustable video output regarding color space I am presuming it is correct. Now the HTPC matches the Blu-ray player & everything looks proper when using calibration test patterns or just playing video.

Just to weigh in coming from the post-production world...and I haven't yet built a HTPC so bear with me.

Lots of references to "color space", "color range", etc. that I hope this clears up.

"Standard" video (e.g. Blu-ray, DVD, DTV, etc.) uses the REC709 color gamut, in the YCbCr colorspace, with a dynamic range of 16-235 (i.e. 1-15 is BTB and 236-254 is WTW). With that said all of these formats are 8-bit formats that have the capacity to carry information in the full YCbCr 1-254 range (YCbCr is 1-254; RGB is 0-255....don't ask) and occasionally you do in fact get content with information in the extremities of the range. Going forward I'll just reference figures in the RGB colorspace range given it's what is more commonly used (and we can debate the YCbCr->RGB conversion another day).

As such, when setting up a system (HTPC or other) you need to consider the difference in setting up the parameters by which the *signal* will be communicated as opposed to how the *content* is displayed.

Many professionals setup their equipment to always pass the full dynamic range (0-255) such that whatever the information contained within the signal is not clipped.

The next step is the trickier one, which is how do you choose to calibrate your display knowing that you you're receiving a full 8-bit signal. When you commonly hear of people stating that "0-255 lifted the blacks" it usually implies that the display was calibrated for the full range (i.e. the blackest bar on a brightness pattern on a test disc was 0 and the whitest bar on a contrast pattern on a test disc was 255). If this is you're environment, when you receive a common video signal at 16 it's going to be "gray." Conversely if you calibrate your display for 16-235 and attempt to play full range content (like a PC game) you will clip information at the display.

Based on the above the recommendation I typically give is the following: 1) setup your entire chain to pass the full 0-255 *signal*; and 2) calibrate your TV such that the blackest bar on a brightness pattern is 16, but the whitest bar on a contrast pattern is 255 (i.e. don't pass BTB, but pass WTW). The reason for this is that, for video content, BTB information is almost never present...any utilization of the expanded range is almost always 235+. Now if you want to optimize both video and PC signals you should calibrate two inputs/video settings (video to not pass BTB; PC to pass).

Now even my above recommendation does have certain potential drawbacks as it relates to overall contrast of a picture if it isn't utilizing information beyond 235. As such some people elect to target something in-between 235 and 255 as the point (e.g. 240)..however that can bring other calibration issues into play (specifically the ability to control red, green, and blue independently to reach the desired white point); there is no "right" or "wrong" answer on this...just a myriad of pros, cons, gives, and takes.

Hope this makes some sense and just my two cents on the subject.

Cheers.
Edited by Manchild - 12/15/12 at 12:16pm

I just tried several different setting combinations on the HD 6450 video card. The “blackest” combination I could think of was setting the Pixel Format to PC Standard (Full RGB) and enabling the Dynamic Range & setting it to 0-255.

I used a couple different black level calibration test patterns & played them using WMC7, WMP, & MPC-HC. I could not display blacker-than-black even with the HDTV’s brightness set all the way to maximum. It lightened up everything but the below black color bars never displayed.

I also used WMC7’s built in setup video which displays the person in a black shirt with the moving B-T-B letter X. With the TV brightness all the way up you could just barely see the moving X, but for all practical purposes it was not visible.

Playing the same DVD with the THX Optimizer in my Blu-ray player it was easy to adjust the TV’s brightness in order to see the B-T-B parts of the THX image.

In other words the TV can display B-T-B, but for some reason the HTPC cannot output B-T-B no matter what. Before I installed the video card I was using the Intel integrated graphics & IIRC was able to see the WMC7 setup video’s moving black X. There must be a video card setting that has to be enabled in order to output B-T-B. It’s probably a moot point because there should not be any B-T-B content in the video image anyway. But it would be nice to know what it takes to do that. If it were not for the Blu-ray player it would be difficult to adjust the TV for a proper black level.

Are you passing the HTPC through a AVR/Processor? Sometimes processors themselves clip the range down to 16-235 before passing on to the display.

If not then my guess is that the range clipping is either in your hardware/CCC or each of the pieces of software are set to output 16-235 by default; you need to find some adjustment/option/preference to enable full range output in the software.

I'm going to assume AMD's 0-255 setting is like Nvidia's video setting "Full (0-255)" in driver 306.97 with my GT430. Then your result is expected. You won't ever see BTB in this mode because RGB values 0-16 have all been mapped to 0. You also won't see WTW. Try the Media Center guy with the white shirt, which is really a WTW test more than it is a legitimate contrast test. If your 6450 is like my GT430, the whites will be blown out in 0-255 mode, and there will be no TV setting you can change to improve this, because everything from 235-255 has been mapped to 255.

Right, and the reason is, your BD player is set to "Limited (16-235)" (or equivalent), to use the Nvidia terminology.

If it was Nvidia, you would set it to "Limited (16-235)", and you would be fine. See follow-up post for much more...

I played with the settings yesterday & before reading the above postings. Setting the Dynamic range to 16-235 now allows for B-T-B.

But it seems counter-intuitive to me. Why would "RGB values 0-16 have all been mapped to 0"? What's the purpose of having a full color range & then compressing part of it?

The nominal range for video is 16-235, with values under 16 being BTB and over 235 being WTW. So a video file can contain pixels with the values in the full range 0-255, but really only those in 16-235 are relevant, or 16-255 if you want to respect WTW, which you normally should. The value 16 is reference black, and BTB should appear the same as reference black, i.e. just plain pure black. The value 235 is reference white, but WTW values are valid and should be displayable if possible for things like transient highlights, which of course means reference white isn't quite as white as the display can get. Spears and Munsil talk about this here:

http://www.spearsandmunsil.com/articles/settingthecontrastcontrol.html

The disconnect is with displays, which go from 0-255 and may or may not have the ability to treat 16-235 as reference black to reference white. If they can't, then 16 will appear as a shade of gray, and the BTB shades will also be visible. The only solution then is to turn down the brightness, which affects the whole picture. To account for this, devices have confusingly named "Limited" and "Full" modes.

It is PC Limited (Nvidia video "Limited (16-235)") that sends untouched RGB 0-255 to the display, while PC Full (Nvidia video "Full (0-255)") expands 16-235 to 0-255, with 16 and below all mapped to 0, and 235 and above all mapped to 255, which is what kills BTB and WTW. It's confusing because "Full" sounds better than "Limited", but it is "Limited" that doesn't touch the video, while "Full" does and actually cuts out BTB and WTW.

I think the proper way to look at this is to consider the target device, which can also have limited and full modes, like my TV, for example. For "TV Limited", the TV considers 16-235 to comprise the range from reference black to white, while "TV Full" means that 0-255 comprises the range from reference black to white. Since video is comprised of pixels in the range 16-235, it makes sense that PC Limited would just send the pixels out untouched; they already have the right values for a display that is also in Limited mode, which will treat 16 as black, 235 as white, but hopefully still allow for WTW, like my TV does. However, PC Full has to do what it does to the pixels so that they will display correctly on a TV Full device, which treats 0 as black and 255 as white.
Edited by tima94930 - 12/17/12 at 4:47am

I've been following this thread for some time now. IDK but my display looks good using the WMC player for Live / Recorded TV and I have the nVidea set to 0-255. I changed MadVR to 16-235 because of suggestions above and my Blu-Ray rips look fantastic now because the blacks are no longer crushed or too dark. There is better gradient. I "calibrated" my HDTV long ago with my BRP using The Digital Video Essentials HD Basics disc and haven't changed the HDTV settings since. I'm pretty happy with the output as it is now. Is it really worth all the extra effort you guys are going through to do this?

While totally confusing, this is also consistent with my limited experience...apparently most video cards treat "Full" versus "Limited" as mapping (or re-mapping) of reference black/white. In my personal opinion that is illogical, but most don't bifurcate transference of a signal and the content. This only gets more challenging when you have to deal with preference within the software as well.

It's totally up to you

By and large the AVS users are far from "average" and seem to perpetually strive for "perfection" (despite whether attainable or not), but that's the fun in all of this!

If you've already calibrated your TV using DVE I'd be willing to bet it is calibrated to a 16-235 range, which is totally fine despite my preference of calibrating to 255. All this means is that you *may* lose a little bit of detail in the highlights of images, but what you *will* have is overall improved contrast. My recommendation would be to leave your TV alone and just optimize the nVidia drivers (and whatever other software) to pass the same range consistent with tima's notes above. The only thing you really want to avoid is having multiple pieces of software/hardware performing range clipping/expansion/re-samping.

From what I've gathered part of the reason your live/recorded TV probably looks acceptable is because WMC itself only outputs 16-235. My hypothesis would be that WMC is passing 16-235 to the nVidia drivers, which is expanding that to 0-255 (which is going to preserve the same data given...just now you have the same black from 0-16 and the same white from 235-255) and passing to your TV, which is displaying the original 16-235 range. Again, in theory, properly setting the nVidia drivers is likely to not vastlying change the dynamic range of the image, but may improve the PQ based on not doing as many manipulations.

Everything you say here makes good sense.

the step being left out is the HDMI black level setting on the HDTV itself. on my Samsung B750, if it is set to 'PC Mode' black levels are automatically set to 'Full' (which is Samsung talk for 0-255). if you choose to not use PC Mode, you have to manually select between 'Normal' (16-235) or 'Full' (0-255)