K2 Edit Composite

K2 Edit Composite is the finishing node of the regional-editing pipeline in the K2 Lab suite of comfyui-FVMtools. It takes the image you edited and composites it back over your original source using a feathered mask - and the detail that makes it worth its own node is that pixels outside the mask are copied byte-exact from the source. A regional edit can never degrade the rest of the image through VAE round-trip loss, because the untouched parts are never touched at all.

That's the masked-inpainting superpower the whole edit-model wave can't match: bit-identical unmasked pixels. K2 Edit Latent does the latent-side editing, and this node does the pixel-side protection that makes the "only the box changed" promise real.

The inputs

• source - the original image. Everything outside the mask is copied from here unchanged.
• edited - the result of the edit pass (typically your sampled + VAE-decoded output).
• mask - where the edit is allowed. Connect the edit_mask output of K2 Edit Latent; that's its intended pairing.
• composite_feather - the pixel-space blend width (default 48). Narrower than the latent feather on purpose: the latent feather blends during denoising, this one softens the pixel boundary afterward.
• strength - opacity of the edit, 0..1. 1 is a full edit, 0 returns the source. A strength between is a manual "tone it down" dial, which is occasionally exactly what a too-strong regional change needs.

Outputs: image (the composited result) and mask (the same mask passed through, handy for chaining or inspection).

The full edit chain

IMAGE → K2 Edit Latent → K2 Regional Sampler → VAE Decode → K2 Edit Composite → Save

Start at low denoise, 64 px latent feather, 48 px composite feather. If a seam shows up, the author's guidance is to widen a feather or enlarge the box rather than raise denoise - seams on regional edits are usually a boundary problem, not a strength problem.

Install

Same as the whole pack:

cd ComfyUI/custom_nodes
git clone https://github.com/ping1979ping/comfyui-FVMtools

Restart ComfyUI, find it under FVM Tools/K2. No extra dependencies.

It's a small node with a small job, and it's easy to underrate. Skip it and paste the decoded edit over the source with a generic composite node and you'll see the difference: the generic node blends everything, so the parts you never asked to change come back slightly different. This node exists specifically so that doesn't happen.