Image Relay

"Image Relay" is a pass-through node: an image goes in, the identical image comes out, nothing is computed. Before you write it off as pointless, know that these little identity nodes are a real pattern in ComfyUI - rgthree-style packs made "power pass-through" nodes a thing for a reason, and this pack ships a whole family of them (image, mask, int, float, string).

What are they actually for? Graph hygiene. A relay gives you a named, placeable point to break a connection, reroute a wire, or keep a value alive while you're reorganizing a graph. Drag a relay into a crowded canvas and suddenly you can split one output to two consumers, or keep a link intact while you delete and replace the node that produced it. Core ComfyUI's Reroute node does a lot of this for free, but Reroute has no visible value - it's just a wire that turned a corner. A relay with a labeled widget is easier to spot, easier to leave documentation on, and (this is the part that matters for some people) it's a typed node that survives round-trips through APIs and JSON workflows that choke on bare Reroute markers.

How it works

It returns its input unchanged. That's the entire mechanism - one return (image,). The value isn't copied or converted; the same tensor comes out the other side.

Inputs and output

• image (IMAGE) - whatever you feed it.
• IMAGE - the same thing, unmodified.

The honest take

For most hobby graphs, the built-in Reroute already does the job, so don't install this pack just for the relays. Their value shows up in two narrower places: first, API or imported workflows where a fixed, typed node name is more robust than a Reroute; second, as a cheap "keep this value pinned" step when you're mid-edit and don't want a hard-to-replace upstream node deleted by accident. If neither of those sounds like you, you can safely skip this one and use Reroute.

Installing it

If you do want it, it's part of longgui0318/comfyui-common-util:

cd ComfyUI/custom_nodes
git clone https://github.com/longgui0318/comfyui-common-util
cd comfyui-common-util && pip install -r requirements.txt

Then restart ComfyUI, or install via ComfyUI Manager by searching "comfyui-common-util". requirements.txt pins only opencv-python, but the pack also imports scipy, scikit-image, and PyWavelets at load - if it fails to load, pip install scipy scikit-image PyWavelets fixes it.