How to Invert a Rotoscope Mask in Kdenlive

In Kdenlive, the Rotoscoping effect is commonly used to isolate a subject from its background. However, you can easily reverse this process to hide the subject and keep the background instead. This article provides a quick, step-by-step guide on how to invert a drawn rotoscope mask in Kdenlive using the effect’s built-in settings.

Step 1: Apply the Rotoscoping Effect

First, drag your video clip onto the timeline. Open the Effects tab, search for “Rotoscoping,” and drag the effect onto your clip.

Step 2: Draw Your Mask

Select the clip in the timeline to activate the rotoscope tool in the Project Monitor. Left-click around the subject you want to hide to create control points, and right-click to close the loop and complete the mask. By default, Kdenlive will isolate the area inside the mask, hiding the background.

Step 3: Invert the Mask

To reverse this and hide the subject instead of the background, look at the Effect/Composition Stack panel (usually located in the top-left or top-right of the interface). Under the Rotoscoping effect settings, locate the Invert checkbox.

Check the Invert box. This immediately reverses the alpha channel, making the area inside your drawn mask transparent (hiding your subject) while keeping the surrounding background fully visible.

Step 4: Add a Background (Optional)

If you want to place a different clip behind your hidden subject, ensure your rotoscoped clip is on a higher video track (e.g., V2) and place your background clip directly beneath it on a lower track (e.g., V1). The area where your subject was will now display the video from the track below.