Join Richard Harrington for an in-depth discussion in this video The Auto Contrast effect, part of Fixing Video Exposure Problems in Premiere Pro.
To help you out Premiere Pro offers a couple of auto effects that will analyze the image and automatically correct it, based on the values that the computer determines. These Auto effects are pretty reliable when you understand how they work. Let's first explore Auto Contrast. In this particular case, I have an outdoor shot and the first instance of the clip in the timeline is as shot. You'll notice it's pretty good but looking at the Waveform Monitor most of the contrast is falling between about 10 and 80, and so our blacks and our highlights just really aren't popping as much as they could.
When I apply the Auto Contrast effect we're using a broader range of the exposure. Let's go ahead and apply that to the last clip here and tweak it ourselves. I'll select the clip, come on over to the Effects tab and then twirl down Video Effects and the Adjust category, and you'll find Auto Contrast. Dragging that on to the clip will analyze the clip and attempt to fix the contrast automatically. We can go on over to the Effect Controls tab where you have the ability to back off the effect with the Blend Original command.
So if it's too strong you simply blend it back mixing the before and the after state. You can manually tweak how much the Black Clips. You don't want to go too far but this can add some contrast to the lower areas. Similarly putting in a little bit of a White Clip will boost the overall whites as well. That's looking dramatically better, a quick AB of the effect shows me that there's definitely improved contrast. There is an important option you want to turn on, however, and that is Temporal Smoothing.
Because this is determining automatic values, it's currently making a new auto value for every single frame. So if something much brighter or much darker were to suddenly enter the frame we can have a quick exposure shift that looked funny. By turning on Temporal Smoothing and setting it to a value of about two, it's going to analyze two seconds before it determines the automatic value, and that creates better playback. So let's just go ahead and take that back and press Play. (Video playing.) You see it's doing a pretty good job.
Now remember this particular effect is not an accelerated effect, so you may need to render it in order to get smooth playback. You can always choose Sequence > Render Effects in Work Area, or press the Enter key to process those effects. Once that's done you'll get smoother playback. Here is the newly processed clip with improved contrast.
That looks a lot better.
- Using the Waveform Monitor
- Toggling effects on and off
- Using color correction effects to fix exposure and tone
- Controlling noise and grain
- Adding keyframes
- Sending projects to After Effects with Dynamic Link
- Extracting backgrounds with the Roto Brush tool
- Adding a vignette to footage
- Working with raw video
- Legalizing video for broadcast