Advanced Green Screen Tutorial: How-To Only Chroma Key Specific Spots of Your Camera in OBS

Using green screen technology is an awesome way to merge the physical and digital worlds together. For the past few months, I’ve been using a green screen and the chroma key feature in OBS to display a digital slideshow within a physical frame.

Though I love the effect it creates, the technology comes with limitations. Chroma key filters don’t just remove your green screen, they remove everything in view with a close enough shade of green. Your clothes, objects, and lights can all get eaten by the chroma key, which is an awful side effect.

Recently, I have discovered a way to minimize the chroma key’s area of effect. Using this particular setup, you can still wear green or use green lights as long as they don’t overlap with your green screen.

Heads up that this one is a bit messy to implement and it does require you to download a third-party OBS plugin. Also, since this requires a third-party OBS plugin, this trick won’t work in Streamlabs OBS. Sorry! But for OBS users, try this technique to focus the green screen effect to just your green screen!

1. Download and install StreamFX for OBS.

2. In OBS, record a snippet of your main camera view. Even a second is more than enough.

3. Open the recording in Windows Media Player or any other media player you use. Take a screenshot from the recording, maintaining the exact dimensions of your view. For example, my camera view is configured to 1920×1080, so my screenshot should be 1920×1080.

4. Open that screenshot in Photoshop or whatever photo editing software you have. Yes, even Paint should do the trick.

The screenshot you took will act as a reference for creating the image mask. Image masks allow you to show or hide any part of a source based on the mask that you apply. In this case, I want to create an image mask that will only display the picture frame behind me.

5. Draw and fill a white box where the frame or your green screen appears.

6. Fill the rest of the area in black. Everything in black will get cropped out. Save the image file.

7. Now go back to OBS. Set up your camera view in the source list.

8. Add the digital image/video that you want to appear as a source. Place it overtop of the green screen, fitting it to the screen as best you can. As you can see in my example above, it doesn’t quite contour to the IRL frame. Also, when I move my arm over the frame, my arm always appears under the image. We’re going to fix that shortly.

9. Add a new source. Thanks to StreamFX, you should have a new source called Source Mirror. This source allows you to make a duplicate version of a source that can be modified without altering the original. Within Source Mirror, add your camera view.

10. Select the Source Mirror version of your camera in OBS. Right click and select “Filters”. Add “Image Mask/Blend”. Then under “Path”, select the image mask file you created. If you’ve done it correctly, you should only see the area with you green screen. Don’t worry if it doesn’t crop exactly to fit your green screen as long as the viewable area shows your green screen in full.

11. Add a Chroma Key filter. Adjust the settings to completely remove the green in view. All you can see now is just the frame of my green screen.

If you’ve set everything up correctly, congratulations! You’ve created a focused green screen effect that only impacts the area around the green screen itself and not the entire camera.

What’s happening here is that everything that isn’t your green screen is displayed on the bottom with no filters. Your digital images/video are in the middle, overtop of your green screen. On top is the heavily edited version of your camera that just shows the area around you green screen. The top layer is the only part that has the chroma key effect applied to it, allowing the images/video to show through. However, that top layer still acts as a camera, allowing for objects or body parts to still appear in front of the digital image.

The only time the effect breaks is when you have something green move into the area. But otherwise, you’re much more free to wear green, use green lights, or have green objects in view!

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