MaskDilate(膨胀)

The node's own display name spells out what it does in two languages: MaskDilate(膨胀) - 膨胀 means "swell" or "expand." That's the entire function: take a mask and push its boundary outward, growing the masked region by a margin you control.

Why you'd grow a mask

Most automated masks are drawn a little too tight. A SAM detection, a CLIPSeg pass, a background-removal cutout - they trace the subject closely, which sounds like a good thing until you inpaint or composite right up against that exact line and get a visible seam, or a thin sliver of the original background peeking through where the model didn't quite paint far enough. Growing the mask by a small margin before you use it gives the generation room to cover past the exact outline instead of hugging it.

This is a different move from mask feathering, which softens the edge of a mask so the transition blends rather than cuts hard - dilate changes the actual coverage, feather changes how sharp the boundary is once it's set. They solve different problems and people commonly use both: dilate first for margin, feather on top for a soft blend.

Inputs and outputs

• mask (MASK) - what you're growing.
• kernel_height, kernel_width (FLOAT, 0–1, default 0.005) - how far the mask expands, one value per axis.
• Output: MASK, same shape as the input, grown.

The gotcha: this isn't a pixel radius

Here's where this node differs from most grow/dilate nodes elsewhere in the ecosystem (Impact Pack, WAS Node Suite), which typically take an integer pixel count - type 8, get an 8-pixel grow. MaskDilate's kernel_height and kernel_width are floats between 0 and 1: a fraction of the mask's dimension, not a pixel count. The default 0.005 means the kernel spans half a percent of that dimension - on a 1024px-tall mask that's roughly 5px, on a 512px mask roughly 2.5px.

If you carry the habit from another pack and type 8 here expecting an 8-pixel grow, you'll get a kernel clamped near 1.0 - spanning the entire dimension - and your mask balloons to cover the whole image. Start in the 0.005–0.02 range and nudge from there; you almost never need to go much higher for a normal margin grow.

Installing it

ComfyUI Manager: search RuiquNodes, install, restart. Or:

cd ComfyUI/custom_nodes
git clone https://github.com/ruiqutech/ComfyUI-RuiquNodes

then restart. No models to download.

Common issues

The mask barely looks different. You're probably still well under 1% - this node's whole range lives in a much smaller window than pixel-based dilate nodes you might be used to. Bump the value in small steps (0.001–0.005 at a time) rather than jumping by whole integers.

The mask suddenly covers almost everything. You've overshot toward the 1.0 end. Dial it back down - remember you're setting a fraction of the whole image dimension, not a pixel count.

Where the output goes. Wire MASK into whatever consumes it next - a KSampler's mask input via Set Latent Noise Mask, VAEEncodeForInpaint, or an image compositing node.