OpenMontage Drama Studio: Pillow for backdrop keying and vision-QA downscaling in an AI short-drama studio

[charliewwdev]

I wanted to share a small project where Pillow ended up doing a surprising amount of the quiet work: OpenMontage Drama Studio, a self-hosted web studio for making AI short dramas (短剧 / 漫剧).

What it does

You start with an idea and move through seven stages: script → cast → scenes → props → storyboard → video → voice → edit. Characters, locations and props get generated (or uploaded) once, then reused as references when each storyboard shot is turned into a clip.

Where Pillow comes in

• Cutting characters and props off the studio backdrop. Generated "costume sheet" images usually come back on a light plate that is not pure #FFFFFF: off-white, light gray, sometimes a faint tint. We open the image with Image.open(...).convert("RGBA"), sample the border and corners to estimate the plate colour, and walk the pixels via im.load(). A pixel is keyed when its luma and chroma are close to that plate. Then we punch enclosed holes (the gap between an arm and a torso), despill the white fringe that sticks to hair and fabric edges, and repair PNGs that were already partially keyed.
• Normalising uploads. Character and prop images that users upload are converted to RGBA PNG before they go through that same keying step, so everything downstream sees one format.
• Shrinking images for vision QA. Before a shot is generated, a vision model checks the prompt against the reference images. Some vision gateways silently drop large base64 PNGs, so we downscale to a max edge of 768 px with Image.Resampling.LANCZOS and re-encode as JPEG (quality=85, optimize=True). That one change made the QA step reliable.

Run it

docker compose -f docker-compose.studio.yml up

This starts the API (which also serves the built web UI), Postgres and Redis. You bring S3 or MinIO storage, an LLM API key, and a Volcengine Ark key for Seedream images and Seedance video (both are paid APIs).

• Repo: https://github.com/charliewwdev/OpenMontage
• Demo: https://openmontage.dtok.io

It's an independent product rebuilt from the AGPL-3.0 calesthio/OpenMontage codebase and is not affiliated with that project. Thanks for Pillow. The pixel-access API made the backdrop keying a lot easier to iterate on than I expected.