Chroma Key

Custom Backgrounds

Sometimes you would like it to appear you are at another location when making a video. Perhaps a field, kitchen, or just a sunny beach!

This process is called keying. If you have ever watched the weather forecast on TV then you have seen this effect in action.

HRH Prince of Wales Presenting the weather forecast in front of a green screen

The easiest keying is using a plain, single-colored background behind the subject. This is called Chroma Key effect. In essence, the editor will turn the colored background to transparent, allowing lower tracks on the editing timeline to show through.

Aside of the novelty of appearing before a tropical beach, there are serious uses for chroma key in making videos. As we work from home more due to the Covid-19 pandemic, we don't always have the luxury of a great background to work from. You may be in your living room or backyard. Chroma key can help hide these shortcomings. 

It can also be used if you want to have a slide presentation in the background, perhaps with your head in a corner.

Backgrounds can be static, as from a still image, or can also be a video clip. Anything visual can be used to chroma key in Premiere Elements.

What You Will Need

You do not need much to create a good chroma key effect. You will need a few supplies and 2 digital assets (clips).

Supplies

1. A green screen with stand (about $35)
2. Backdrop lighting so that the green screen is evenly lit
3. A light for the subject that provides illuminating similar to the setting you will use for a backdrop. If you plan to be in a bright field mid-day, use bright lighting coming from a source higher than your head. In an office or kitchen use softer light. This takes practice to get right. Chroma key always looks a little "off" so just do your best. No one will mistake it for real life, on-location footage.

Digital Assets

You will need 2 clips to use in your project:

1. Foreground subject recorded with audio and a green screen background
2. Background still shot (jpeg file) or movie clip at least as long as the foreground clip. No sound is needed, but if there is sound in the video clip you will need to mute it or adjust the level.

Import these assets into your project. The rest of the process is done in your video editor.

How to Edit

It is easy to add a chroma key effect to your videos. Follow these steps:

1. Add the foreground and background assets to your project
2. Place the green screen clip (foreground) now. Make sure the foreground is on a track above the background. For example, place the background clip will be on Track 1, place your green screen footage on Track 2. 
3. Trim the green screen clip
4. Add the background to a track below the green screen.
5. Trim or edit the background track's length so it is the same as the green screen clip.
6. Edit the sound level of the background clip, if needed.

This video is from an older version of Premiere Elements, but the process hasn't changed in the current version.

Chroma Key and Videomerge in Premiere Elements

Adobe's help page covers some definitions and describes some other effects tools you can use to superimpose a foreground over a background. Visit it here.