Resize Mask

Masks and latents live at different resolutions, and ComfyUI will happily error out the moment they disagree. A mask generated at 512×512 won't line up with a 1024×1024 latent, and half of "why is my inpaint broken" is exactly that mismatch. Resize Mask is the fix: give it a target width and height, and it returns a mask at that size.

It's from ComfyUI Extended, the dependency-free pack, and it's one of those quiet nodes that prevents an entire class of failures rather than fixing them after the fact.

How it works

Three inputs that matter:

• mask (MASK) - what you're resizing.
• width / height (INT, 0–8192, default 512) - the target. Here's the useful bit: set either one to 0 and the node preserves the aspect ratio, computing the missing dimension from the other. Set both to 0 and it passes the mask through untouched.
• interpolation - nearest-exact, bilinear, area, bicubic, or lanczos (default nearest-exact).

Output is a single MASK at the target size. A mask already at the target size is returned as-is without resampling - no wasted work.

The interpolation choice

• nearest-exact (default) - no smoothing, fastest, keeps hard edges crisp. Right for masks you'll use as strict cut-outs.
• bilinear / bicubic - softer edges after resize; handy when you're also planning to blur.
• area - a good pick for downscaling masks, it averages neighborhoods and holds up better than nearest.
• lanczos - the highest quality, and the only one implemented via PIL (the others use torch's interpolate), so it's the slow one. Reach for it when upscaling a mask matters visually.

Install

cd /path/to/your/ComfyUI/custom_nodes
git clone https://github.com/rookiepsi/comfyui-extended.git

Restart ComfyUI; it's under comfyui-extended/mask. Or ComfyUI Manager → search "ComfyUI Extended" → install → restart. Zero dependencies, no downloads.

Common issues

• 0 × 0 passes through. If both dimensions are zero the mask comes back unchanged - deliberate, but easy to mistake for a bug when you left defaults and nothing happened.
• Hard edges + bilinear = fuzzy cut. If you resize a hard mask with bilinear or bicubic, you get soft edges you didn't ask for. Use nearest-exact unless feathering is the goal.
• Aspect-ratio mode needs a nonzero number. Width 0 + height 0 is the passthrough case, so give one of them a real value if you want the aspect-preserving behavior.

The honest take: it's a utility you'll mostly reach for when something errors or looks wrong. Wire it in front of latent-sized operations and a whole category of "mask size mismatch" bugs stops existing.