Mask Combine

Combine two masks into one: add them, cut one out of the other, keep only where they overlap, and more. Optionally feather both before combining.

In ComfyUI	Add Node → ComfyUI-JH-PixelPro → mask → Mask: Combine
Good for	Adding a hand-painted area to an automatic mask, cutting eyes out of a skin mask, keeping the overlap of two selections

When to use it

This is the mask version of Photoshop's selection modes: add to selection, subtract from selection, intersect with selection. mask_a is your base mask and mask_b is the one you apply to it.

Operation	Result	Think of it as
union	Larger of the two values at each pixel	Add to selection (keeps soft edges)
add	a + b, clamped to 0..1	Add, with overlaps brightening
subtract	a - b, clamped	Subtract B from A
difference	a * (1 - b)	Cut B out of A, with soft edges respected
intersect	Smaller of the two values	Only where both overlap
multiply	a * b	Overlap, with soft values blended
xor	Where only one of them is set	Everything except the overlap

Quick start

1. Connect your main mask to mask_a and the second mask to mask_b.
2. Choose operation. For "cut the eyes out of the skin mask", use difference with the eyes as mask_b.
3. Leave blend_mode on hard unless the edges need softening.
4. Check the result with Mask Preview.

Settings

Setting	Default	What it does	Tip
operation	union	How the two masks are combined.	See the table above.
blend_mode	hard	hard uses the masks as they are. soft_feather blurs both masks first.	Use soft_feather for a smooth blend between regions.
opacity	1.0	Strength of the operation. 0 returns mask_a unchanged; 1 gives the full result.	0 to 1. Lower it for a subtle edit.
feather_sigma	0.0	Blur strength (pixels) used by soft_feather.	0 to 64. Has no effect in hard mode.

Output: mask (MASK).

Tips from retouching

• Order matters for subtract and difference: mask_b is removed from mask_a.
• Both masks must have the same width and height. One of them can be a single-frame mask used for a whole batch.
• To soften only the result, combine with hard, then feather with Mask Edge Smoother.
• Combine a Luminosity Masking mask with a subject mask using multiply or intersect to adjust only the highlights on the subject.

Under the hood

Inputs are clamped to 0..1. In soft_feather mode both masks get a Gaussian blur (kernel = 2 * round(3 * sigma) + 1, replicate padding). The operation runs on the (possibly blurred) masks and is clamped; the final result is a * (1 - opacity) + combined * opacity. A batch of 1 is broadcast against a larger batch. Source: core/mask_combine.py.

Related nodes

• Mask Morphology to grow or shrink one input
• Mask Edge Smoother to soften the result
• Luminosity Masking for tonal masks to combine
• Mask Preview for checking the result

Example workflow

Mask Combine example workflow. Copy workflows/sample_portrait.jpg and workflows/sample_binary_mask.png into ComfyUI/input/. It intersects the subject mask with the Luminosity Masking highlights, with soft_feather on the edge, so only the bright parts of the subject stay selected. It uses only core ComfyUI nodes and this pack.