How to replace an object in video with local AI

The short answer

In KwaFlux, replacing an object in video means keeping the object and swapping what is behind it: click the object on one frame, let SAM2 tracking follow it, then pick a transparent, solid, gallery, or blur background. It is for non-person subjects; people go to person replace. Erasing the object is a different tool. Use Object Background Replace.

When object replace beats person replace

• The subject is a bottle, sign, car, or other prop — not a portrait
• You want a click-to-track mask, not a person-tuned body matte
• You need an alpha or a simple plate swap without After Effects

What still needs a compositor

• Heavy occlusion, motion blur, or a target that looks like the background
• Multi-layer VFX or a tracked camera move
• You need a ProRes 4444 or WebM alpha for someone else's graph

How to use the module

1. Import the clip and click the object you want to isolate
2. Pick transparent, solid, gallery, or blur; preview 1s/3s/5s on a hard frame
3. Export locally, or send the composite through Video Converter

Check the plate on a hard frame

The plate you pick is a delivery choice, not a quality ladder. Transparent keeps an alpha so another editor can drop the tracked object onto a different background. Solid fills behind it with one color. Gallery places a still you choose. Blur leaves the original scene and softens everything outside the click, which helps when the prop should stay put and the street should fall back. You are marking an object in footage you are cutting — a bottle, a sign, a vehicle — and swapping that region.

SAM2 follows the click through the shot. Undo, redo, and regenerate live in the annotation rail when the outline climbs onto a wall or a table that shares the object's color. Park the free 1s, 3s, or 5s preview on that hard moment: a turn, a pass behind another prop, or a frame where the edge should stay sharp and does not. A calm opening frame will hide the crawl. The preview needs no account. Sign-in and a paid plan are needed to export, convert, repair a file, or download a file from a link. Both run on your machine.

AI Object Remover fills a hole so a walker or a parked bin can disappear. Object replace keeps the thing you selected and changes the plate behind it, or hands you the alpha. If the bottle should vanish, use the remover. If the bottle should sit on a clean field, stay here. Portraits still belong in AI Smart Cutout, where the matte is tuned for hair and a body. A prop in someone's hand can be the click target. Do not ask this module to cut the person.

The cases that still need a compositor do not get easier because the plate looks tidy on a still. Heavy occlusion, motion blur, and a target that blends into the background remain hard. Multi-layer effects and a tracked camera move are still a graph in another app. When a partner needs ProRes 4444 or WebM with alpha, export the alpha and let their project finish the stack. Video Converter can change the codec of a composite you already trust, and that step stays local too.

A useful pass is short on purpose. Import the clip and click the object once, on a frame where its outline is clear. If the first mask includes the table, the sky, or a second similar prop, regenerate and click again rather than hoping the export will settle. Then pick the plate that matches the handoff. Transparent when someone else will composite. Solid or gallery when this file is the finished look. Blur when the object stays in the scene and you only want the surroundings to recede. Watch the timed preview on the worst motion. If the edge holds there, export locally. If it does not, change the click or move the shot to a compositor.

Keep the job on footage you have the right to edit. The click selects an object inside that shot. Product shots, B-roll, and UGC are the ordinary cases: one prop or vehicle, tracked on your GPU, with the original file kept beside the export. The image on this page shows the module with a clip loaded and nothing marked yet, so it shows no replacement. Judge your own 1s, 3s, or 5s preview instead.

Similar color is the failure you should go looking for. A dark bottle against a dark bar, a white sign against an overcast sky, or a car that matches the road will invite the mask to wander. Click the object on a frame where the boundary is obvious, then scrub to the frame where it is not, and run the short preview there. If regenerate cannot hold that boundary, the honest next step is a compositor, not a longer export of the same mask.

• Click a prop, sign, or vehicle in the clip you are editing
• Transparent, solid, gallery, and blur are plate types, not ranked modes
• Judge the short preview where the object is occluded or close in color to the background
• Use removal when the object should disappear, and this module when it should stay
• Export only after the hard frame holds, and keep the original file