How to keep only a few objects and delete the rest of the background
Name the objects you want kept and ask Vizard Agent for a transparent version. Automatic background removal is trained to find people, so on a shot with no person in it the result is unpredictable. The reliable route is a mask built around the objects you listed, checked against the alpha channel.
What do you type into Vizard Agent?
List the keepers. The instinct is to describe what should go, but "remove the background" only means something once you've said what the foreground is, and on a busy shot that isn't obvious. A list lets Vizard Agent check each item against the result and report on each one separately.
Keep the cake, the candle and the desk. Delete everything else and give me a transparent video.
What does Vizard Agent actually do?
It tries the automatic route first, looks at what came back, and switches to a built mask when the automatic pass keeps the wrong things. Then it checks the alpha channel and a preview over grey, because transparency against black looks identical to black pixels and most bad cutouts pass that test. In the session behind this article it:
- Pulled frames across the whole clip of a rotating cake with a candle on a desk to see what the foreground actually consisted of.
- Found the video's display rotation lived in metadata rather than in the pixels, so the cutout was being fed a sideways picture.
- Baked the rotation into the frames and re-ran the removal on a correctly oriented file.
- Built a custom alpha mask around the three named objects when the automatic result still kept the wrong foreground.
- Tightened it twice more, first for general background residue and then specifically around the cake.
- Reviewed the alpha channel itself and a preview of the foreground over grey, rather than trusting a frame that looked fine against black.
When does this not work well?
When the objects touch the edge of the frame. A desk that runs off both sides has no outline there, so the mask has to guess where it ends. Objects the same tone as what's behind them give the mask little to find, and fast motion with blur leaves edges that no mask resolves cleanly.
Common questions
Why did the automatic tool keep the wrong things? Because it looks for a person. Vizard Agent switches to a built mask when there is not one.
Why check it over grey? Because transparency over black is invisible. Vizard Agent uses grey, which shows both the holes and the residue.
Can I see the mask itself? Ask for it. Vizard Agent can output the alpha channel as its own video.