ComfyUI-AutoPickMask (IMGLAB)

A ComfyUI custom node that accepts one image and up to 8 mask inputs, compares dimensions, and outputs the first matching mask — with configurable edge-case handling and an optional fallback (else) mask.

Installation

Drop the ComfyUI-AutoPickMask/ folder into ComfyUI/custom_nodes/ and restart ComfyUI.

ComfyUI/
└── custom_nodes/
    └── ComfyUI-AutoPickMask/
        ├── __init__.py
        ├── nodes.py
        ├── README.md
        └── js/
            └── auto_pick_mask.js

Inputs

Input	Type	Description
image	IMAGE	Source image — defines the target resolution
on_multi_match	combo	Behaviour when multiple masks match the image size
on_no_match	combo	Behaviour when no mask matches the image size
mask_1 … mask_8	MASK	Dynamic slots — next slot appears as each one is connected
else_mask	MASK	Fallback mask — only visible when on_no_match = Use Else Mask

Outputs

Output	Type	Description
image	IMAGE	Direct passthrough of the input image
matched_mask	MASK	First mask whose dimensions match the image (or fallback)
rgba	IMAGE	Input image with matched mask as alpha channel [B,H,W,4]

Edge Case Options

on_multi_match — when 2+ masks share the image's exact dimensions:

Option	Behaviour
Use First (Top Priority)	Silently picks the lowest-numbered slot
Raise Error	Halts the queue listing the conflicting slot numbers

on_no_match — when no connected mask matches the image size:

Option	Behaviour
Output Empty Mask	Outputs a zeroed mask (RGBA will be fully transparent)
Use Else Mask	Reveals an else_mask input slot; uses it as the fallback output
Raise Error	Halts the queue listing the sizes that were connected

Note: If Use Else Mask is selected but else_mask is not connected, the node will raise an error rather than silently fail.

Node UI

• Image slot — shows resolution (W×H) in grey after execution
• Mask slots — show resolution coloured green (match) or red (mismatch); unconnected slots show a faint grey dot
• Else mask slot — shows a fallback label in amber; only visible when on_no_match = Use Else Mask
• Mask slots expand automatically as you connect them (up to 8), and collapse when disconnected