Fixing Backlit Video in Adobe Premiere Pro

Many of us use conferencing systems like Zoom and others to produce interviews that we broadcast live and later on VOD. Often you can't control the quality of the video coming in from the remote participant.

In this interview with Jon Wilson, president and COO of Telestream, who approved the use of his video in this tutorial, we see that because he's in front of a bright background, the webcam shut down the brightness on his face, which causes a condition called backlighting (Figure 1, below). In this tutorial, you're going to learn how to fix this in Adobe Premiere Pro using Lumetri Color and Lumetri Scopes.

Figure 1. There's a backlighting issue in the remote guest's video on the right. Click the image to see it at full size.

Applying the Effect and Creating the Mask

There are two aspects to adding the effect. First you have to apply the effect and create a mask so that only the desired portion of the frame is going to be affected by the effect you're applying.

To begin, go back to Premiere Pro's Edit workspace, and apply Lumetri Color here. Then go into Effect Controls, create a mask, and apply the mask over the remote guest's region of the video so that the effect is only applied to that region (Figure 2, below).

Figure 2. Creating the mask. Click the image to see it at full size.

When Premiere Pro creates the mask, by default it adds a slight feather on it so you won't see a stark line between where the effect is applied and where it's not applied. Once you've applied the mask, go back into the Color workspace.

Configuring the Effect Using the Luma Scope

What I absolutely love about working in Adobe Premiere Pro's Color workspace are the various available scopes, and the Waveform scope in particular. In this example it's set to Luma, which means we're only seeing the Brightness pixels, because color is fine in this video. The Luma scope shows us the Brightness levels of the pixels in the frame, on the IRE scale from 0 IRE for black pixels to 100 IRE for white pixels (Figure 3, below).

Figure 3. The Luma scope is on the far left. Click the image to see it at full size.

When we look at my (left) side of the video, it's probably too bright, and I did adjust that in the final video before I shipped it. But here we're focused on the major problems in Jon's video on the right. And we see in the Luma scope that there are no pixels approaching the 100 IRE level because everything was clamped down because of the backlit background. We also see that there's no pixels around 0 IRE.

So the blacks are going to look a little bit faded, but the biggest problem is the exposure on the face. And when you're exposing a face, you want the exposure level to be around 70 IRE if the face is Caucasian, which obviously it is in both cases here. It's always fun to move a slider, because then you see movement, which tells you where the face is. And we see the bright spots up in my forehead, which are too high, and that's my fault with lighting. I didn't do a good job there.

But more importantly, we see Jon's face is way down here in the lower half of the Luma scope and that's why it's so dark. So job #1 is to boost this to around 70 IRE.
And then we wanna look at making sure the whitest whites are toward the top of the waveform, which won't be a problem, but more importantly, that the blackest blacks are well down in the lower portion, and to adjust that I use the Exposure control. There are dozens of ways to do this, and this is just how I do it.

Watching the face in the waveform, you can adjust the exposure until you see the face is up to 70 IRE, and what we've done effectively in this video is to crush the whites (Figure 4, below). We've lost all detail in the window shades in the background because we've pushed all the brightness levels up, but that really doesn't matter because there's no detail we care about people seeing there. And we really care more about getting consistency between my facial brightness and Jon's.

Figure 4. See the lost detail in the background of Jon's image. Click the image to see it at full size.

Then, if we look down in the lower portion of the Luma scope, we see that some of the blacks have been pushed off 0 IRE. We can adjust this by dragging the waveform on the right down a little bit, and then we can see the mostly in the zippered area and the background area of Jon's video. And now we're getting a little bit better contrast.

The waveform now shows that there's a lot of bunching right around 100 IRE. That's the whites we blew out. You could try and drop those a little bit, but whenever you do that, you're going to drop the facial value as well. There are lots of little dials and levers you can mess with. And then you can always see where you started and see where you finished. So I would say mission accomplished from a brightness perspective.

Fixing Softness in the Image

We're still seeing a little bit of softness in Jon's image, and that's what I want to fix next. It's definitely secondary to the color issue that we just addressed, but I want to show you the Unsharp Mask as well. The Unsharp Mask gives you controls that you can use to adjust where and how the sharpness filter is shown and/or applied.

So, apply the effect, then open the Effect Controls. Obviously, we have the same issue with sharpening only Jon's region. In Figure 5 (below), you can see what I mean from a softness perspective.

Figure 5. Our too-soft image and Unsharp Mask effect controls. Click the image to see it at full size.

So we've got Unsharp Mask applied and the controls we're going to use primarily are Amount, which is obviously the amount of the adjustment radius, which is how far the adjustment goes from edges spotted in the video by Adobe Premiere Pro; and Threshold, which gives us the ability to set areas where the effect is applied. As you adjust these settings to sharpen the image, you can clic on/off to compare the original image to the effect of the Unsharp Mask being applied. You can also adjust the Radius, but e careful not to go too far when adjusting the radius because you can get a pretty bizarre result. You actually may not need any adjustment of the radius.

You can see in Figure 6 (below) that the blurriness on the side of Jon's face is gone. And if you go back to full screen, everything looks a lot more normal.

Figure 6. Blurriness gone

And that's how you adjust brightness and sharpness with Adobe Premiere Pro, particularly using the masks available in all filters.