MASK CROP MASTER — ComfyUI Custom Node

Always-square mask crop, even at image edges.

The Problem

When you mask a region at the edge of an image, the standard Mask Crop Region node from was-ns produces a rectangular crop instead of a square. This happens because it clamps the crop dimensions when the square extends beyond the image bounds.

The Solution

MASK CROP MASTER repositions the square instead of clamping it. When the crop would extend past an image edge, it slides the square inward so it always fits completely inside the image.

was-ns (rectangle):              MASK CROP MASTER (square):
┌────────────────────┐           ┌────────────────────┐
│████████████░░░░░░░░│           │░░░░░░░░░░░░░░░░░░░░│
│████████████░░░░░░░░│           │░░████████░░░░░░░░░░│
│░░░░░░░░░░░░░░░░░░░░│           │░░████████░░░░░░░░░░│
│░░░░░░░░░░░░░░░░░░░░│           │░░░░░░░░░░░░░░░░░░░░│
└────────────────────┘           └────────────────────┘
  400×200 (broken)                 400×400 (correct)

Installation

cd ComfyUI/custom_nodes
git clone https://huggingface.co/YOUR_USERNAME/MaskCropMaster.git

Restart ComfyUI after cloning.

Usage

Drop-in replacement for Mask Crop Region from was-ns:

Remove the old Mask Crop Region node from your workflow
Add MASK CROP MASTER from the WAS Suite/Image/Masking category
Connect the same inputs: mask, padding, region_type
Connect the same outputs: cropped_mask, crop_data, coordinates, dimensions

Inputs

Input	Type	Default	Description
`mask`	MASK	—	Input mask
`padding`	INT	24	Padding around the bounding box before squaring
`region_type`	COMBO	"dominant"	"dominant" or "minority" (was-ns compatible)

Outputs

Output	Type	Description
`cropped_mask`	MASK	Square-cropped mask
`crop_data`	CROP_DATA	Compatible with `Mask Paste Region`
`top_int`	INT	Y position of the square
`left_int`	INT	X position of the square
`right_int`	INT	Bottom edge
`bottom_int`	INT	Right edge
`width_int`	INT	Width (= side length)
`height_int`	INT	Height (= side length)

Compatibility

Works with Mask Paste Region from was-ns (same crop_data format)
Same output names → minimal rewiring needed
Tested with ComfyUI latest version

License

Apache 2.0