CopyMakeBorder

Sometimes you just need to add pixels around an image. CopyMakeBorder is the pack's wrapper around OpenCV's copyMakeBorder - it grows an image by border_size pixels on all four sides, and lets you choose how those new pixels are filled. It sounds trivial, but padding matters more than you'd think: compositing, contour work (objects touching the canvas edge), tiling, and collage prep all behave better with a deliberate border.

The name is pure OpenCV heritage - "copy make border" is literally cv.copyMakeBorder.

How it works

• image - the source IMAGE.

• border_size - pixels added on every side (default 64).

• border_type - the fill strategy, the whole point of the node:

  • BORDER_CONSTANT (default) - solid color padding. Note there's no color input on this node, so "constant" means black. If you want a colored border, pad with constant then composite, or use a different tool.
  • BORDER_REPLICATE - repeats the edge pixels outward. Great when you want a border that visually continues the image.
  • BORDER_REFLECT / BORDER_REFLECT101 - mirrors the image across the edge (101 omits the edge pixel itself; it's the classic OpenCV "mirror with a seam-free center" option). Good for textures where you don't want a hard edge.
  • BORDER_WRAP - wraps around, as if the image were a cylinder. Useful for seamless tiling.
  • BORDER_DEFAULT / BORDER_ISOLATED - variations on the others.

Output: the padded IMAGE.

Why you'd bother

• Contour sanity. OpenCV contour-finding treats shapes touching the canvas edge awkwardly. Padding with REPLICATE (or a constant) before Contours keeps blobs whole.
• Tiling. BORDER_WRAP or REFLECT padding makes tile edges blend instead of clipping.
• Compositing layouts. Add breathing room around a subject before pasting it into a collage.
• VAE/scale workflows where dimensions need to be divisible or padded for the next node.

The selection logic is simple: constant = plain solid pad (black here), replicate = stretch edges, reflect = mirror, wrap = tile-around. For 90% of mask/CV work you'll want REPLICATE or REFLECT.

Gotchas

The missing color input is the one real surprise - BORDER_CONSTANT gives you black, always, because the info schema exposes no border color. Don't assume you can pick it; if you need a colored border, pad with constant and overlay, or use a compositing node.

Install

cd ComfyUI/custom_nodes
git clone https://github.com/bmad4ever/comfyui_bmad_nodes
cd comfyui_bmad_nodes
pip install -r requirements.txt

or install "comfyui_bmad_nodes" via ComfyUI Manager and restart. OpenCV does the work; no models. It's a boring node that quietly un-breaks a lot of CV pipelines.