If you want to skip the origin story, go straight to the TL;DR further down the page.
I’ve been trying to come up with a simple solution to limit the video signal in Premiere, and avoid potential QC issues. I’ve graded a couple of projects in Premiere recently, and it’s always a pain to make sure no values go below 0 and above 100 (or 0 and 255, or 16 and 235, depending on how you define your luminance values, but I’m talking about pure black and pure white here).
Premiere has a Video Limiter filter, which does a good job of bringing some of the crazy values back in range if you set it up correctly, but it never seems to be doing a perfect job of clipping the values that can’t be displayed anyway.
Why is it important? Because when the file goes through QC, some places can be pretty particular about illegal luma values, and will flag the issue. There’s a bit of tolerance before being rejected, but it’s good to play it safe. I’ve worked in broadcast QC earlier in my career and that was the main issue being constantly flagged. FCP7 and a simple filter to fix it, but now that Premiere dominates the market, the issues are popping back (not to mention it’s not something people have in mind when delivering for web).
But even for web, this is a good thing to use. Some video players, in some web browsers (I haven’t done a test in a while but from memory I believe that the Vimeo HTML5 player was the main culprit) will adjust the white point of your video based on your highest value. Meaning if you have a 100% white background, on your video, but some values go above, to say 102%, the player will bring down the luma level of your whole video so the 102% shows up as 100%, and the 100% value will be washed down to around 98%, meaning slightly off-white, which might be an issue if for example you want to white video to blend into a white page. Even more frustrating is that this behaviour is completely inconsistent and the same video on a different browser might look fine (clipping the value above 100% as you see it in Premiere).
For this reason, I’ve been looking for ways to clip the illegal values in the image in Premiere. Usually it’s not an issue for me since I tend to grade in DaVinci Resolve, which doesn’t produce any illegal values (it works internally using the full data range, and scales it “down” to video range on monitoring/export, so those illegal values just don’t exist). If you use Resolve, you’ll see that if you push values above 100, it will just clip. In Premiere, it will go over in the “superwhites” territory.
I’ve tried a lot of solutions. Setting up the Video Limiter effect properly (it does the job right 90% of the time but still gets tripped by very saturated parts of the image and never brings it back fully into range), looking for plugins (there are none), making custom LUTs (LUTs ignore values under 0 and above 100 and just leave them untouched), and terrible workaround (the worst one was using the Cineon plugin twice, once Log to Lin, once Lin to Log, which does the job but is not an accelerated effect, which means it needs rendering, and it’s probably affecting the quality of the image).
Finally I settled on the best workaround I’ve found so far. Here it is:
TL;DR: How To Limit Video Signal in Premiere
I use a 0% black matte set to “Lighten” composite mode, and a 100% white matte set to “Darken”. I put them both on top of my edit (white above black), and they just remove the unwanted values. You need both layers, because if you only use the white layer to clip the highlights, the video will appear white when there is nothing on the timeline (which is different from having “black”).
First step it to create two Color Mattes, one set to Black (HSL values 0,0,0) and one White (HSL values 0,0,100, or if you want to play it even safer, 99). Drop them on top of your timeline, covering the whole edit. I’d recommend putting it on top of graphics too, as the most regular offender of creating illegal values.
If you’re not familiar with these composite modes, here’s the way it works: for Darken it takes the 100% white solid, and says “look underneath it, and everything that is darker that this, show it, otherwise show the white matte”, which effectively replaces every “superwhite” value by pure white. And vice-versa for the black matte and the “Lighten” mode.
I like this solution because it doesn’t need to be rendered, and it doesn’t affect the visible signal in any way. It also replicates the way DaVinci Resolve handles these values, and I’m used to working like this.
You can also use it in combination with the Video Limiter effect (which should be on an adjustment layer underneath the two solids). It’s not very straightforward to use (I might do another quick post on what I find are the best settings) but it’s good for bringing crazy saturation back in range softly, instead of just clipping it. Personally I prefer to do this in the grade, shot by shot, but that’s also from the habit of Resolve not having a similar filter.
You can set it up before you start grading, and grade “under it” so you see the effect directly, or you could opt to grade first, seeing the superwhite and superblack values, bringing them back in range manually, and then adding the solids on top at the end.
Personally I’d use the first method if not for one big caveat: most of Premiere’s Lumetri panel sections (the Basic and the Curves which I mainly like to use) do NOT bring superwhite and superblack values back in range. So if you use the exposure/black/white sliders, the values above under 0 and over 100 will stay untouched and be clipped. The only section of the Lumetri panel that allows to bring those illegal values back in range are the Color Wheels. Frustrating.
Here you go. If you’ve ever had a project knocked back from QC with illegal luma values, or if you’ve wondered why your white video background is now off-white, you might find this useful.