The brief
The original plate is two actors at a table with a tablet, shot in a white room with sheer curtains and soft, even light. A good take with no atmosphere. We wanted the same two people in a corner cafe at blue hour. Pendant lamps overhead, a city street through the window, other customers in the background. Nothing about the performance could change: the eye lines, the hands, the hair, the tablet. We ran the shot through Beeble SwitchX for the roto, the background replacement and the relight, then judged the result against the untouched original in a split screen.
Shot and delivered
DeliveredShotWhat made it hard
Replacing a background is the easy half of a hybrid shot. The hard half is light. In the original, the actors are lit by one big soft source from the left and white walls bouncing everything back, so there is almost no shadow on the faces. Drop those actors into a cafe with warm practicals overhead and a cool window behind them and the eye knows immediately that they were never there. The light on the skin doesn't agree with the room. On top of that, the matte has to hold on hair, glasses and fingers moving over a tablet screen, every frame, or the whole illusion falls apart at the edges.
How we did it
The plate is the foundation and everything SwitchX produces is a layer on top of it. First a roto and mask of both actors, so the room can be replaced without touching them. Then the background: the cafe, the window and the street outside are a new environment placed behind and around the original framing, table and coffee cup included. Then the relight. SwitchX generates normals and depth for the actors, and we used those to light them from the new room, a warm key from the pendant lamp on the right and cooler fill from the window on the left, rather than painting light on by hand. The performance underneath is exactly what was shot.
What SwitchX actually is
SwitchX is Beeble's mask-based video-to-video tool. You lock the parts of the frame that must not change, in this case the two actors, and it rebuilds everything around them from a reference of the new environment. It is the same technology BYKAI used on CROOKS, billed as Southeast Asia's first AI-hybrid series, where the performances were shot in one controlled space and the locations were built around the actors in post.
Watch BYKAI and Beeble's CROOKS behind-the-scenes on YouTube
Why not just grade it warmer?
A grade changes the color of the light that is already there. It can't move the key from the left to the right, or put a rim on a shoulder where there was none. Relighting from normals and depth changes where the light comes from, and that is what sells the actors as being in the room. The grade comes after, to tie the layers together.
Where the work still is
None of this is a finished shot on its own. The matte needs checking on hair, glasses and fingers crossing the tablet. The relight has a narrow sweet spot: push it and skin turns to plastic, hold back and the actors float in front of the room instead of sitting in it. We go through it frame by frame, keep the plate underneath, and matte the relit actors back in only where they are needed.
The tool changes the room. It does not change what the actors did, and it does not do the judging. That part is still a person at a monitor, the same as it was for a green screen.
Where this fits in a production
For a commercial or a short film, this is a way to shoot a performance in a controlled space and decide on the environment later, without an LED volume, a location move or a set build. It is not a replacement for shooting the real cafe when the real cafe is available and the light is right. We treat it as one more tool in the compositing kit, next to the roto, camera tracking and relighting we already do by hand, and we use it where it saves the production something real.
Behind the scenes
- Original plate: a white room with sheer curtains and soft, even light, 5 seconds at 1080p
- Both actors roto'd and masked in Beeble SwitchX so the room could be replaced without touching them
- New environment: a cafe at blue hour with pendant lamps, plants, background customers and a city street with traffic through the window
- Relight driven by the new room: warm key from the overhead practical, cool fill from the window
- SwitchX takes ProRes 422 HQ at a constant frame rate; ProRes 4444 and variable frame rate files are rejected
- Performance, wardrobe, hair and the tablet are untouched from the original take
- Delivered as a split screen so the before and after can be judged side by side
