Most content makes use of the entire screen real-estate. However, there are some situations where you will want to limit the part of your screen that is captured. In this tutorial, I’ll show you how to only capture a part of your screen using OBS Studio.
There are actually a few ways to accomplish this, each with its own benefits and drawbacks associated with them.
Table of Contents
Method 1: Only Capture a Part of Your Screen Using Game Capture
| Benefits | Drawbacks |
|---|---|
| Will never capture another application you don’t intend | Some applications aren’t seen by the Game Capture Source (Like Chrome) |
| Captures the entire application, and nothing more to the pixel | No complex shapes are supported (See Method 2) |
| Uses the most efficient capture method on OBS Studio | |
| Very easy to implement | |
| Allows other methods to be used alongside it to fine-tune the area captured |
The first method I will be covering to only capture a part of your screen is the Game Capture method which is configured to capture a specific application. This partial capture method ensures that you don’t accidentally reveal personal information from foreground applications, like checking your email while on stream, and will prevent things like the Steam Overlay from being captured by default, revealing your friends list to your audience.
As you can imagine, I don’t think your friends would appreciate being bugged by people who watch you. Keeping that information private is just a bit of good stream etiquette. This partial screen capture method is the easiest to implement that I know of.
To add the Game Capture source and specify the application:
- Open OBS Studio
- Under Sources, Left-click the + sign
- Select Game Capture (It’s already added in the above picture)
- Set the mode to “Capture Specific Window.”
- Select your Application in the Window Section – in my case, Space Engineers
Tuning the Capture Further with a Crop
Now, you can further tune the partially captured content by cropping a specific area into a partial screen capture. This is done by:
- Left-Alt + Left-click on one of the edge handles (The red squares located around the active source in between two corners)
- Drag the handle inward until you see a green line
The green line indicates that the content is cropped off. You can undo the crop by holding the Alt key again and dragging it in the opposite direction until it turns red.
This process remains the same for the following methods, aside from the fact that the source type changes.
Method 2: Partial Screen Capture Using Masking for Complex Cropping
| Benefits | Drawbacks |
|---|---|
| Supports complex shapes | Complicated to set up |
| Very versatile | Matching the aspect ratio is important |
| Requires external image editing programs |
The next method of capturing only a part of your screen makes use of the image mask filter to specifically hide a complex shape that standard cropping can’t create. For example, say you stream Path of Exile. In that game, the health and mana are represented as circles. Therefore, the standard crop wouldn’t work very cleanly if you wanted to say, create a second, larger version located elsewhere on your screen in a more prominent location.
This means that you’ll need an image mask to get the specific area of the screen you are targeting. You’ll also likely need to create the mask file yourself, as getting a complex cropping shape to your exact needs isn’t likely available on the internet.
This partial capture process is also handy if you use LumiaStream, as their basic Rectangular RGB Overlay element can be masked to look much more refined using a mask.
Just be warned, this process to capture only a part of the screen in OBS is highly involved and may frustrate you if you end up masking the wrong area or use the wrong aspect ratio in the masking process.
Don’t worry; it’s actually very easy to create a mask file –
- Open up an image manipulation program like Gimp, or Photoshop
- Create a screenshot of the content you want to mask – I use ShareX to make that process much easier
- Import the Screenshot into Gimp or Photoshop
- Create a new layer above the screenshot layer
- Use the Fuzzy Select tool in Gimp with the screenshot layer active, and left-click, hold, and slide your mouse out from the area you want to mask
- Select the inverse, and press the delete key
- Activate the second layer
- Select inverse again
- Color in the area with #FFFFFF white
- Save the image to a folder somewhere on your computer as a .png
And now you have the mask file for the resolution you screenshotted for. Next, you just need to apply the mask file to your source in OBS. To do this:
- Add a second game capture source for the same program
- Right-click the source
- Select Filters
- Under Effect Filters, Left-click the + button
- Left-click Image Mask/Blend
- For the Type, you want the “Alpa mask” color channel or alpha channel (you may need to play with this a bit depending on how you do the mask.
- Browse to your mask file location
- Ensure White #FFFFFF is the color being masked.
Now, the source should be completely invisible, minus the area that you colored in white. You should be able to then crop it using the first method, resize it, and position it wherever you like on the canvas.
Conclusion for How to Only Capture a Part of Your Screen in OBS Studio
Between these two methods of cropping content for partial capture, most situations should be covered. These two methods combined together are especially effective in achieving a precise capture. I hope that this article has helped you to achieve the look you are going for!