Using a Green Screen / Chroma Keying

So you want an interesting and professional background when you present online? Given how increasingly prevalent online presentation is, you might want to consider the possibility of using a technique called Chroma Keying, also known as green-screen.  

What you’ll need:

1. Green material – fabric or screen or poster board. Vivid and flat color works best.
2. Daylight, high-lumen light bulbs and lamps to place them around you.
3. A webcam.
4. A cross-platform streaming and recording program, like OBS Studio. 

The steps to doing this are straightforward:

Step 1: Rotate your desk so that your back is against a wall.

Step 2: Attach the matte green fabric to the wall behind you so that it is centered behind your head. I bought a panel that was 40″x40″. 

Step 3: Position the lamps facing you. Color rendering is important, you need daylight bulbs to generate light with many of the properties of sunlight so the green color is correct to the camera. You also need the bulbs to have high lumens so the camera can have as much light as it needs to do a good job.  Try to avoid creating strong shadows on the background – I placed the lights beside me rather than in front of me for that reason.

Here’s what my desk looks like:

Note: The following has only been tested on Windows.

Step 4: Install your streaming and recording program and configure the chroma key. I used OBS Studio https://obsproject.com/ and https://obsproject.com/forum/resources/obs-virtualcam.539/.

Step 5: Configure OBS Studio. 

1. After starting the program, click the + button under Scenes and name it “webcam with chroma key”
2. Click the + button under Sources, add “Video Capture Device”, and name it “webcam”.
3. Right click on the webcam, choose Filters, then under Effect Filters click the + button and choose Chroma Key.  Defaults for Green should work.
4. To add a background image, under Sources, click the + button, choose Image, and select the image you want. Make sure the image is shown in the correct order–you want your webcam image to be layered above the background image so you see through to the image behind.  Right-click on the image and click on Order, and select “move to bottom”
5. To start the virtual camera (it’s assumed you installed the plugin already), select Tools on the menu bar, then click VirtualCam, and start it up.  You should now be able to select a camera called OBS-Camera from other applications like Zoom, Hangouts, Skype, etc.

A few notes: 

• Consider using an external plug-in webcam so that you can better manipulate the camera’s position and angle for your circumstances. In other words, taking video from the location of the laptop’s hinge isn’t necessarily the best view.
• Play around with the camera settings directly, adjusting the zoom, exposure, focus, and so on, to see what works best.
• Lock the exposure and focus on the camera. If you don’t do this, the camera will occasionally re-focus and change exposure settings automatically, distracting your viewers.
• Consider whether you should use a headset for audio. Most of the time, audio from a headset is much clearer and avoids the possibility of echo.