OBS Studio Luma Key: Make Grayscale Video Transparent

Using a grayscale video overlay in OBS Studio is a great way to add custom transitions, alerts, or effects to your live stream, but you need to make the black or white background transparent first. This guide provides a quick, step-by-step walkthrough on how to use the “Luma Key” filter in OBS Studio to key out specific brightness levels, turning any grayscale video into a clean, transparent overlay.

Step 1: Add Your Video Overlay Source

1. Open OBS Studio and locate the Sources dock.
2. Click the + (plus) icon and select Media Source (or VLC Video Source).
3. Name your source, click OK, browse for your grayscale video file, check Loop (if desired), and click OK.

Step 2: Open the Filters Menu

1. Right-click on your newly added video source in the Sources list.
2. Select Filters from the context menu to open the source filters window.

Step 3: Add the Luma Key Filter

1. In the bottom-left corner of the Filters window, click the + (plus) icon under the Effect Filters section.
2. Select Luma Key from the list.
3. Keep the default name or rename it, then click OK.

Step 4: Adjust the Luma Key Settings

The Luma Key filter works by targeting brightness (luminance) values rather than specific colors. To make your grayscale overlay transparent, adjust the sliders based on what you want to remove:

• To Remove Black (Keep White):
  • Set the Luma Min slider slightly above 0.00 until the black background disappears.
  • Adjust the Luma Min Smooth slider to soften the edges between the transparent and visible parts of the video.
• To Remove White (Keep Black):
  • Lower the Luma Max slider below 1.00 until the white background becomes transparent.
  • Adjust the Luma Max Smooth slider to blend the remaining black graphics smoothly.

Step 5: Fine-Tune the Output

• Use the Smoothness sliders to eliminate harsh pixelated borders around your graphics.
• If the overlay appears too translucent, adjust the Opacity slider back to 1.00 or tweak the Contrast slider within the Luma Key settings to make the remaining elements pop.

Once the background is completely transparent and the overlay looks clean, click Close on the Filters window. Your grayscale video will now overlay seamlessly onto your stream.