Green Screens with Chroma Key in OBS

Hello and welcome to this simple tutorial on how to use green screens with chroma key in OBS Classic!

Over the past year and a half, streaming on Twitch and other streaming platforms has become a kind of “arms race.” Viewers are looking for the highest quality picture, experienced players and good graphics. By using this guide, you will be able to increase your productivity many times over thanks to the green screen or chroma key technology built into OBS Classic and really easy to use. Here are some things you need to consider if you want to move forward in performance levels.

Enjoy this incredibly dumb weather forecast example to get an idea of the level of accuracy you can get when using the green screen by following the instructions.

Table of Contents

Green screen type

Do you want a screen made of one color or two? Beware of Cheap Two-Tone Green Screens! The best green screen fabric is Muslin… Muslin is a kind of unfinished, finely woven cotton fabric that absorbs light well. This is what you need, because it is necessary for the material to absorb light, and not reflect it. The reflected green light will hit you and in the background you will become translucent around the

edges. Avoid “green screens” that are made of shiny materials like this Cowboy Studios green screen (yes, I have one. It is very bad.) Choose long sizes to make sure you can get enough of it. For your convenience, the green screen I am using here. You need to place the green screen evenly along the wall, if you have folds in the fabric, you will have problems with the keying.

Webcam

I am using Logitech C920. It was chosen as the best webcam on the market and the C910 was the best before. These cameras deliver crisp 1080p images and are a great addition to your chroma key. I highly recommend this webcam as it ensures that it will work properly with your chroma key. And in case you’re wondering, yes, the C920 has two built-in microphones and will work in stereo. However, the sound quality is poor.

Cheaper cameras and poor lighting will create an uneven or pixelated picture. You need to make the picture static and well lit, otherwise it will be difficult for the “green screen” to create a rich picture.

Lighting

Perhaps one of the most important aspects is lighting. Thanks to the light, you can protect your camera from third-party software enhancements that can create an uneven picture. The more colorful pixels you see, the better your lighting should be. Look for indirect light sources. A softbox is perfect for this. Make sure you don’t have sunlight behind the green screen. Otherwise, it will create changes for your screen, which will entail certain difficulties.

Position

The further your green screen is from your camera and you, the better. I work in a small studio, so I have a distance of about half a meter. 1.5-2 meters would be ideal. But again, it all depends on the reflected green light that can be thrown at you or the object that you want to capture in the green screen. Try changing locations and see for yourself how you feel better.

You need to add your webcam to global source. This means that your C920 will be set up the same regardless of the scene. Instead of Scene → Source → Add Source → Video Capture Device … go to Add Source → Global Source and you will find the C920 Chroma, which needs to be added using the button in the first circle.
Add a source, I just named mine C920 Chroma.
When you see it in the list, click on it and select properties.
Now the magic is happening. Activate the chroma key and start experimenting. Here are a few tips that I found helpful when I set up my chroma key.

When choosing your color, choose between the darkest and lightest. But not the darkest green, and not the lightest green. Keep in mind that when you change the Similarity setting, you are moving both up and down in terms of color. Choosing a dark color means that when you move the Similarity parameter up, it will try to find colors that are darker than necessary.
The “Similarity” parameter is the most important to configure. If you’ve taken into account all aspects (correct lighting, screen location, webcam quality, from page 1) you shouldn’t raise the “similarity” above 100. Similarity dramatically expands the range of color you are going to create.
The mixing parameter speaks for itself. It will smooth your video by mixing colors into larger pixel groups. Typically, “Similarity” and “Blend” should be adjusted together. It doesn’t help that the “similarity” is higher than the “mixture” or vice versa. If your “affinity” is higher than the “blend”, then it will create the colors you want. If the “blend” is too high by the time you find your color through the Similarity color range, the pixels will get too large and begin to eat away at the image you are about to save. As mentioned, experimenting with small adjustments is always encouraged.
And the last, but nevertheless important point is “scatter reduction”. This parameter, often overlooked, creates a uniform image (no seams). Essentially, this setting adds more red to your image by removing green that can be difficult to project, such as the area around hair or objects with holes.

So, when everything is set up, play with the scenes, add your new C920 Chroma from the Global Sources list and get cool! This little 30-second clip is an example of setting / overlaying a League of Legends game I’m using in conjunction with the green screen. Enjoy customizing your screen and write if you have any comments or questions.