How to Use the Luma Key Filter in OBS Studio

This guide provides a straightforward walkthrough on how to use the Luma Key filter in OBS Studio to remove backgrounds based on brightness levels. You will learn the difference between Luma Key and Chroma Key, the step-by-step process to apply the filter to your sources, and how to fine-tune the settings for the best visual results in your streams or recordings.

What is a Luma Key?

Unlike a Chroma Key (which removes a specific color like green or blue), a Luma Key filters out parts of an image or video based on luminance, or brightness. It is highly effective for removing solid black or solid white backgrounds from overlays, alerts, logos, and special effects.

Step-by-Step Guide to Applying Luma Key

Follow these steps to apply and configure the Luma Key filter in OBS Studio:

Step 1: Select Your Source

1. Open OBS Studio.
2. In the Sources dock, locate the video, image, media, or browser source you want to edit.
3. Right-click the source and select Filters (or select the source and click the Filters button above the sources dock).

Step 2: Add the Luma Key Filter

1. In the Filters window, locate the Effect Filters section in the bottom-left corner.
2. Click the + (plus) icon.
3. Select Luma Key from the list.
4. Give the filter a name (or leave it as default) and click OK.

Step 3: Adjust the Filter Settings

With the Luma Key filter selected, you will see several sliders in the properties window. Adjust them to achieve the desired transparency:

• Luma Max: Adjusts the upper limit of brightness. Lowering this slider will begin to key out (make transparent) the brightest areas (whites and light grays) of your source.
• Luma Max Smooth: Controls the softness of the transition for the bright areas. Increase this to prevent jagged edges on keyed-out white sections.
• Luma Min: Adjusts the lower limit of brightness. Raising this slider will begin to key out the darkest areas (blacks and dark grays) of your source.
• Luma Min Smooth: Controls the softness of the transition for the dark areas. Increase this to create a smoother fade for keyed-out black sections.

Tips for Best Results

• To Remove Black Backgrounds: Keep the Luma Max at its default maximum value (1.00) and gradually raise the Luma Min slider until the black background disappears. Use Luma Min Smooth to soften the edges.
• To Remove White Backgrounds: Keep the Luma Min at its default minimum value (0.00) and gradually lower the Luma Max slider until the white background disappears. Use Luma Max Smooth to clean up the edges.
• Source Quality: Luma Key works best on high-contrast sources. If your subject shares similar brightness levels with the background you want to remove, parts of your subject may also become transparent.