Do I need a 4K Monitor for Grading?

[Brett Allbritton]

Hey everyone,

This might be a question that exposes my ignorance, but recently I was asked if I could grade a 30 minute documentary for someone. I happen to do a lot of color correction for my job as well as just for fun when I want to mess around in Resolve, so I was confident that I could do what the director was asking for (she said she wants it to look true to life, so mostly just primary corrections it sounds like).

 

Then she told me that the footage was V-Log 4K shot on the Panasonic EVA1 and asked if I have a 4K monitor, which I don't.

 

What I do have is an IPS 1920x1200 monitor, specifically a ProArt ASUS PA248Q, and a ColorMunki. I have graded C100, FS5ii, GH4, and even downscaled RED footage on this monitor with good results, but because she specifically asked if my monitor is 4K, I'm beginning to wonder if maybe my monitor wouldn't be accurate enough for her project.

 

As far as I know, the only problems I would have are judging sharpness and noise, but as far as color goes it should be fairly accurate regardless of my monitor's resolution as long as I calibrate properly, right? Or is there something I'm missing here? I'd love to help with her project, but I also don't want to waste her time. What do you guys think?

[Frank Wylie]

Profile your monitor to the proper colorspace and use HD proxies and render @ 4K; it will work.

 

Blackmagic just made their Resolve 15 Certification materials free. Build a proper pipeline and it will work. The information is there for free.

 

If your friend is hung up on the resolution, I'd pass. Resolution has nothing to do with color correction; the colorspace and proper monitor calibration does.

[Bruce Greene]

You are correct. You don't need a 4k display to grade a 4k project.

 

But you do need a calibrated REC709 display. I'm not sure you can calibrate your display to REC709 using a color munki and it's software. If you want to try, 1st set your display via the display's own controls to "sRGB" or "REC709" if that's offered. Then run the calibration. But, Resolve is not .icc profile aware software, so if you are using a PC, you won't get a display calibration that can be used with Resolve. On a Mac, you should be ok ish.

 

The best solution would be to use DisplayCal, open source software to create a 3D display LUT that you will load into Resolve for grading. But here, you will have a bit of a learning curve, both for Resolve perhaps, and DisplayCal. The are documents on the DisplayCal site to describe the process, but you may well find them difficult to follow as they are not perfectly clear for newbies.

 

So, if you are up for an adventure in display calibration and learning color correction in Resolve, this can be an opportunity, but don't try this on a deadline!

 

For further help and information, visit the DisplayCal forums and liftgammagain.com forums. Good luck!

[Brett Allbritton]

Thanks, Frank. The Resolve Certification materials are especially interesting, I'm definitely going to look into that!

 

I'll tell her I can do it then. I figured that would be the case, but having never owned a 4K monitor and not being a pro level colorist I wasn't sure if there was something I might be unaware of.

 

So out of curiosity then, what benefits does a 4K monitor offer specifically in terms of color grading?

[Brett Allbritton]

Hey, thanks, Bruce. I wasn't didn't know that Resolve isn't .icc profile aware, which muddies things a bit. I do have access to an i1 Display Pro at work that I might be able to calibrate my home monitor with while working on this project, but unfortunately, in this case, I am on a PC.

 

I'll definitely take a look at DisplayCal. The editor hasn't finished working on the film yet, so maybe I have a little bit of time to study beforehand.

[Bruce Greene]

Hey, thanks, Bruce. I wasn't didn't know that Resolve isn't .icc profile aware, which muddies things a bit. I do have access to an i1 Display Pro at work that I might be able to calibrate my home monitor with while working on this project, but unfortunately, in this case, I am on a PC.

 

I'll definitely take a look at DisplayCal. The editor hasn't finished working on the film yet, so maybe I have a little bit of time to study beforehand.

The iOne Display probe will be better than a monki for display calibration, but everything else I mentioned still applies. Apps like Photoshop will work with your .icc display profile on a PC, but Resolve will not. So, in your case, you might be best served by setting your display to sRGB or REC709 and using the iOne Display to just manually set the white point accurately using the display's own controls and leave it at that. Then make sure all color management is turned off in your PC. Actually, do this first, then adjust the display with iOne Probe and software for white point and don't create a profile that will get loaded into the OS.

 

I checked the specs on your display. If possible, disable the "

ASUS Smart Contrast Ratio" as it will make inaccurate images for color correction.

[Frank Wylie]

+1 on the Display Cal Software!

 

It's as good (in my opinion) as any commercial grade color management software and they specifically support DaVinci Resolve calibration of a grading monitor with a Decklink card.

 

You can, of course, use it on systems that do not have a decklink card, but READ UP on the documentation! It IS a bit of a learning curve.

 

https://displaycal.net/

[Frank Wylie]

Thanks, Frank. The Resolve Certification materials are especially interesting, I'm definitely going to look into that!

 

I'll tell her I can do it then. I figured that would be the case, but having never owned a 4K monitor and not being a pro level colorist I wasn't sure if there was something I might be unaware of.

 

So out of curiosity then, what benefits does a 4K monitor offer specifically in terms of color grading?

 

Depending on the monitor, it might cover more of the desired colorspace natively without resorting to such drastic internal color management.

 

You also get to say "4K " a lot...

 

Seriously, if you use internally generated proxies or proxies on the fly, it taxes the system more heavily doing the conversions on the fly. A native 4K monitor takes the burden of dynamic scaling and colorspace conversion (provided it has the native colorspace), off of the GPUs, provided your data pipeline can handle the 4K overhead. Better have a good 0 RAID or a fast SSD or a SSD 0 RAID.

 

Bottle necks are typically I/O data from source discs to GPU and to Cache drive. Get a SSD for a dedicated Cache drive, have a good fast RAID for Source material and NEVER save files you are working on BACK to the drive from which you are working.

 

You can mitigate this by Pre-rendering HD proxies of the 4K files, but then it gets more complex matching back to the original 4K files.

[Tyler Purcell]

So few things.

 

1) To get 10 bit full raster, you need an I/O video card of some kind. Unfortunately, with DaVinci, you have to use a blackmagic video card. I have a Decklink Extreme 4k PCI card.

 

2) Most monitors are 8 bit and can't display full raster. This is a huge problem when grading because you'd be stuck viewing REC709 8 bit 4:2:2 at best.

 

3) You will need to calibrate whatever monitor you plan on using. Honestly, my LG professional grading monitor in RGB mode is damn close to spot on stock. So some monitors maybe close enough stock.

 

4) DaVinci loves down-resing to 1080p for display, it actually speeds up the playback process of 4k material because it doesn't have to work as hard real-time rendering.

 

5) The EVA-1 camera shoots in a very compressed file, so it's very taxing on the system to playback in real time. You will need fast storage and a decent GPU in order to play it back in real time. I have a GTX 980 and it struggles with EVA-1 footage.

 

6) No you don't need a 4k monitor to grade, but you do need everything else above in order to make sure you've got any semblance of color accuracy.

[Vince Sweeney]

Recently sat in on a 5-day long feature grade with a 20+year experienced, full-time Hollywood based colorist who does regular work for NBC broadcast shows and other major networks. His suite is Resolve based and uses a Sony HD grading monitor.

[Perry Paolantonio]

2) Most monitors are 8 bit and can't display full raster. This is a huge problem when grading because you'd be stuck viewing REC709 8 bit 4:2:2 at best.

 

With an 8 bit monitor, the screen can't show as many colors simultaneously, but this has nothing to do with the color space. All the colors you can show are still within the specified color space for that screen, there are just fewer of them on screen at the same time. The potential downside of this would be banding, where the screen has to average color values that are too similar to render smoothly as a gradient, resulting in areas where you might get the same colors over several pixels, causing a banding effect. Here's a great (simple) explanation of why 8 bit is fine for grading: https://www.liftgammagain.com/forum/index.php?threads/clarifing-notions-10bit-gamut-32bpc-settings.12140/#post-121144

 

Flanders Scientific 8-bit screens are perfectly good for many grading scenarios. They also do some clever dithering to make banding artifacts pretty much disappear. I got a demo at NAB a few years ago from them with the same frame on both an 8 and a 10 bit screen of the same size, side by side. The differences were imperceptible. You could really only tell there was a variation if you brought up the onscreen color picker and went to the same screen coordinates to see the numeric difference in displayed color values.

 

Their AM210, for example, can easily display Rec709, SMPTE-C and DCI P3. At $2000, it's not a bad price either, considering you get lifetime factory recalibrations, and it's highly capable in terms of inputs and tweaking.

Edited February 8, 2019 by Perry Paolantonio

[Bruce Greene]

 

 

2) Most monitors are 8 bit and can't display full raster. This is a huge problem when grading because you'd be stuck viewing REC709 8 bit 4:2:2 at best.

I disagree Tyler :)

 

It's important to do the grading math at very high bit depth, but, once corrected, 8 bit 4:2:2 is fine for viewing and judging color corrections as long as the display is properly calibrated. And viewing at 8 bit won't prevent one from rendering the movie in 16 bit RGB uncompressed if they'd like.

 

Brett, the original poster, is kind of just starting out with this stuff. It will be confusing enough for him as it is. He doesn't need 10 bit RGB display to do his work now. I have a 10 bit display and Decklink card, but I usually have it set to 8 bits though as I get a little bit better performance in Resolve, and it doesn't effect my color decisions.

[Tyler Purcell]

Perry is right, the Flanders Scientific uses an 8 bit display, but 12 bit electronics. I was referring to 8 bit electronics and 8 bit display, which is what most sub $1000 monitors are.

 

However, 8 bit vs 10 bit and 4:2:2 vs full raster, they're night and day on my grading monitor. You see the differences in dynamic range and most importantly, less color bleeding between channels.

[Perry Paolantonio]

the quality of the output is more a function of the bit depth of the source footage, I believe, than about the processing inside the screen.

 

If you have a monitor that's capable of displaying the whole color space, the only real downside of an 8-bit screen is banding because it just doesn't have enough colors available for simultaneous display. That's where Flanders excels - by dithering nicely so you don't really see that. Cheaper monitors meant for computer display won't bother with the hassle of adding dithering because they don't need to for 99.9% of their intended market.

 

color space defines the parameters -- the range of available colors.

bit depth defines the number of colors available for a pleasing display within that color space at any given time

 

Will a 10 bit pipeline with a 10bit display look better than an 8bit pipeline with an 8bit display? Probably in some cases with certain types of footage, yes. But as long as both screens have a gamut big enough to display the standard color spaces we're concerned about, the question becomes: "do you mind seeing a bit of banding once in a while, knowing that it's likely just you hitting a limit of your display?" If so, get a Flanders or get a higher bit depth monitor. But it doesn't mean it can't be accurate within a given color space as long as that space is within its gamut.

 

10bit argument has become a bit of a religious one in some circles. It really depends on the end user's requirements whether it makes financial sense to step up to a significantly more expensive 10 bit screen for what usually amounts to a nominal improvement.

[Tyler Purcell]

Yea, bit depth of source is the most critical. In the case of the EVA-1, it's most likely captured as 10 bit 4:2:2.

 

I do a lot of keying work and the difference between 8 and 10 bit is night and day. Banding, aliasing and most importantly color bleeding are all an issue. Now of course, you could just assume that it will be fine on the output. However, if your output is a .h264 file, all of those issues would be there in the playback. If you played the 10 bit files using an application on your computer, it would be 8 bit as well since operating systems are still all 8 bit. So how could you even check if what you're doing is right? That's the reason why I recommend a full raster 10 bit system, because it's really the only way to make sure what you're doing is accurate.

 

Honestly, nearly all of my work is 12 bit 444 4k these days. The difference between 10 bit and 12 bit is not noticable, so playback of that format is irrelevant.

[Phil Rhodes]

I think there are some circumstances under which a full-resolution display is necessary, or at least useful. Quite often, the grade will also be the online edit, which may mean it's the point at which any final QC issues with focus, lens consistency, compression, grain or noise are detected. For instance, rescuing underexposed shots, or even just matching material shot in different circumstances, might involve adding or removing noise or grain to keep things consistent. In extremis this might just mean zooming in to a 100% (or larger) view, but it's really better to have things be properly visible, all the time.

[Perry Paolantonio]

I do a lot of keying work and the difference between 8 and 10 bit is night and day.

 

I was responding to your assertion that:

 

2) Most monitors are 8 bit and can't display full raster. This is a huge problem when grading because you'd be stuck viewing REC709 8 bit 4:2:2 at best.

 

 

Grading and image quality evaluation are different things. You don't need a 10 bit display to do color grading. If you're QCing the image quality you would see an advantage in a 10 bit display for sure. But the OP's question and your response to it are about color evaluation, for which you don't strictly need a 10 bit display.

[Tyler Purcell]

Grading and image quality evaluation are different things.

But nobody here is talking about a commercial workflow. We're talking about a home studio, where the colorist will be the only set of eyes seeing the film in an uncompressed format on a calibrated monitor in 10 bit. I mean, the last 3 features I did, the viewing pass we did at my house was the final before we made the DCP and screened it in theaters. Nearly everything that comes out of my bay is critically watched and then released directly. Nobody else has a 12 bit Pro Res XQ file but me.

[Robert Brahms]

I know ... old post but still often asked, that's why: I would even go further and say that a full DCI 4k Monitor in a useful color grading cockpit studio size isn't very helpful to check sharpness (unless it is the showroom monitor) because of its very high pixel dense. You would need a very large monitor to not get tired checking sharpness on such small pixels. I kicked them out of our grading rooms because even the grading software interface was unreadable (tiny fonts etc). To check sharpness you eather tend to zoom in to 100% 4k and check the sharp parts, not the whole picture. Therefore a UHD or even WQHD monitor is enough. Every video player or ffplay is able to be set playing unscaled 1:1 and you move the needed part into the monitor range. Sharpness should be checked long before grading anyway.

[Aapo Lettinen]

one does not usually need the 4k monitor for GRADING itself and it would need to be pretty large screen to benefit anything from it. But some kind of full resolution quality control device is essential and it better be as large screen size as possible to detect compression artifacts and sharpness problems. You will want to check compression and sharpness with the large screen, the colour stuff can be done with smaller real grading monitor. I personally do dailies grading with calibrated 27" display but the quality control part with a uhd 75" tv which is by my opinion just enough to detect problems if the material is intended for cinema release. There surely is better options for large screen quality control if wanting to spend tens of thousands to it but the as-large-as-possible-consumer-TV is the best one can do if not having budget for over 65" full 4k grading monitor. 

the problem with "4K" tv's is that they are not DCI4k but UHD so a little bit of scaling or side cropping is needed when viewing a dci image. Documentaries may be made in UHD from the beginning so it should be a non issue then. Just don't grade with that consumer tv, it is not enough for that job even if properly calibrated. it can be used for client preview during grading though, it might be good enough for that even if the colors vary a bit compared to the real grading monitor. the client is probably more happy with the larger image size and the small nuances are less important