Sub-Pixel Mask Refiner

JHPixelProSubPixelMaskRefiner is the node you reach for right after SAM, YOLO, or rembg hands you a chunky binary mask. Those masks are hard-edged, aliased, and off by a pixel or two - fine for inpainting, terrible for compositing. This node turns them into a sub-pixel alpha mask: a guaranteed-1.0 interior, a guaranteed-0.0 exterior, and a Gaussian-feathered band in between. That's the difference between a cutout that looks glued on and one that survives contact with a different background.

How it works: it binarizes your mask at threshold (0.5), erodes by erosion_radius to define the "definitely inside" core, dilates by dilation_radius for the "definitely outside" core, then Gaussian-feathers the uncertain band by feather_sigma. The output is float32 in [0,1] - exact 1.0 inside, exact 0.0 outside, a smooth ramp in the middle. It's the classic cutout workflow in one node.

The knobs that matter:

• erosion_radius (default 2) - how much of the interior to protect as solid.
• dilation_radius (default 4) - how far out to guarantee background. Keep it ≥ erosion_radius for a stable feather band.
• feather_sigma (default 2.0) - the softness of the transition, 0.1..32.
• threshold (default 0.5) - binarization level applied before morphology.

Output: refined_mask, a single MASK. Feed it into a composite, an alpha matte chain, or use it as an inpaint mask with a bit of blur.

One honest limitation: erosion and dilation use a square kernel (Chebyshev metric), so with radius > 16 edges get slightly boxy rather than rounded. For normal portrait work at radius 2–8 you'll never notice.

Install is the shared pack install:

cd ComfyUI/custom_nodes
git clone https://github.com/jetthuangai/ComfyUI-JH-PixelPro.git
cd ComfyUI-JH-PixelPro
pip install -r requirements.txt

Restart and it's under ComfyUI-JH-PixelPro/mask, or use ComfyUI Manager → search "ComfyUI-JH-PixelPro".

Troubleshooting: it's float32-only - there's no precision pin, so don't expect float16 speedups, and large feather_sigma values need the float precision to stay clean. If you set both radii to 0 you get a bare Gaussian feather of the raw mask, which is a decent quick edge-softener in its own right. And midtone masks are fine as input - they get thresholded before morphology, so only the 0/1 decision matters; the geometry comes from the threshold, not from your mask's softness.