# I built a ComfyUI node for AI roto: click one person, get a native 4K hair matte (SAM3 + LTX-2.5 alpha-gen, open source)
Canonical: https://social-archive.org/hjbhjh/UA0B5KIW2g
Original URL: https://www.reddit.com/r/comfyui/comments/1xi9f4s/i_built_a_comfyui_node_for_ai_roto_click_one/
Author: Last_T_Rex
Platform: reddit
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## Content
I'm a VFX compositor, and hair on a busy plate is the roto job nobody wants. So I built a node that does the first pass. How it works: \- Click the person on the plate (alt-click cuts a part, shift-click adds a prop). SAM3 picks them. \- The other people get inpainted out of a copy of the plate, then LTX-2.5 alpha-gen draws the edge of the one person left. On its own LTX mattes everyone in frame, so this is how you aim it. \- On 4K plates it runs LTX again on native 1920x1088 tiles along the edge, so the strands are real, not upscaled. \- Overlap mode handles hair or hands crossing another person. Depth Anything decides who's in front. On a 247-frame shot the edge detail match was 88.7%, against 45.0% for SAM3 + ViTMatte and 29.4% for a plain SAM3 mask. Runs on 12 GB VRAM and 16 GB RAM, EXR in and out, plate frame numbers kept. Open weights only, GPL-3.0. It's in the Manager as "Comfy Pro Alpha Generator". Repo: [https://github.com/rik-python/ComfyUI-Comfy-Pro-Alpha-Generator](https://github.com/rik-python/ComfyUI-Comfy-Pro-Alpha-Generator) Full demo with chapters: [https://youtu.be/2EGYEsRpmTw](https://youtu.be/2EGYEsRpmTw) If you throw a shot at it, tell me where it breaks.
## Media
1. video: https://social-archiver-api.social-archive.org/media/archives/hjbhjh/wYiUm26GZf/00-video.mp4