A rectangular webcam box in the corner looks fine, but a clean circular or rounded face-cam instantly makes an overlay feel more designed and modern. OBS can crop your camera into any shape using image masking, and once you know the trick it takes just a couple of minutes, no external editing required.
How masking works in OBS
OBS has a built-in “Image Mask/Blend” filter. It uses the transparency of a mask image to decide which parts of your webcam remain visible. Feed it a white circle on a transparent background and only the circle shows; the corners vanish, leaving a clean round face-cam. The same technique works for hexagons, rounded rectangles, or any custom brand shape.
Two ways to do it
The classic method uses an alpha mask image (a PNG shape). Newer OBS versions also include a color key and crop workflow, and some setups use the “Rounded Rectangle” approach with a mask for soft corners. The alpha mask is the most flexible because you control the exact shape.
Step by step
| Step | Action |
|---|---|
| 1 | Create or download a white shape on a transparent PNG |
| 2 | Right-click your webcam source, choose Filters |
| 3 | Add “Image Mask/Blend” under Effect Filters |
| 4 | Set Type to “Alpha Mask (Alpha Channel)” |
| 5 | Browse to your PNG shape and apply |
For a perfect circle, your webcam source should be cropped to a square first (hold Alt and drag the edges, or use a Crop/Pad filter) so the circle is not stretched into an oval. Match the mask image’s aspect ratio to the cropped source and the shape stays true.
Polishing the look
Once masked, add a subtle border by placing a matching ring or frame graphic on top in your scene. A thin outline in your brand colour makes the round cam pop against gameplay. Keep the shape reasonably large enough that your face is clearly visible; over-shrinking a circular cam hides expressions your viewers connect with.
Reusing masks across scenes
Once you build a masked webcam you like, you rarely want to rebuild it for every scene. Use a single webcam source referenced across scenes, or turn your masked cam plus its border into a nested scene (a scene used as a source) so any tweak updates everywhere at once. That keeps a consistent look between your gameplay, chatting, and starting-soon layouts without duplicating filters.
Custom shapes open up branding possibilities beyond a plain circle. A hexagon, a rounded square, or a shape echoing your logo all work as long as the mask PNG has a clean alpha channel. Just remember that unusual shapes can crop parts of your face if you move, so leave a little margin and test your normal range of motion. A shape that looks striking when you sit still should still frame you when you lean or gesture.
Frequently asked questions
Why is my circular webcam stretched into an oval?
Because the source is not square before masking. A circle mask applied to a 16:9 webcam gets stretched horizontally. Crop the webcam to a 1:1 square first using Alt-drag or a Crop/Pad filter, then apply the round mask and it will be a true circle.
Does masking reduce webcam quality or performance?
The quality impact is negligible; masking simply hides pixels outside the shape. Performance cost is tiny, well within any modern GPU’s budget even with several masked sources. Cropping to a square before masking is more about geometry than performance.
Bottom line
Use the Image Mask/Blend filter with an alpha-channel PNG to crop your webcam into a circle or any shape, and crop the source to a square first so circles stay round. Add a matching border graphic for polish. It is a quick, free way to make your overlay look custom-designed rather than a plain rectangle.
