Group Preview Display

Group Preview Display is the viewer half of the two-node gallery system in comfyui-floating-preview. Put one on the canvas, give it a tag, and it turns into a tile that collects every image sent by GroupPreview emitters sharing that tag - a stack you can click through instead of a canvas dotted with previews. The best part is right there in the node description: it has no image input. It can't block your pipeline, ever. You can leave it sitting on the canvas for weeks and it will never hold up a queue waiting on data.

You'll want one when you're iterating - tuning a LoRA, sweeping prompts, comparing checkpoint outputs. The normal ComfyUI rhythm is preview tiles you have to pan around to see; this collapses one stage's outputs (or several, if you tag them all the same) into a single browsable stack. Since it costs nothing to run, it's the kind of node you leave parked in your working graphs rather than something you add per-project.

How it works

The Python side is almost embarrassingly thin: display() just reports its tag over the UI and returns nothing. All the real work lives in the pack's frontend JS, which is why the node is so cheap to run. The JS listens for preview images arriving over ComfyUI's binary websocket, looks up which GroupPreview node sent each one, reads that node's tag, and buckets the image into a tag-keyed map. Then it refreshes every GroupPreviewDisplay on the canvas whose tag widget matches, loading the images into the node's tile. At the start of each execution it clears the map, so every run gives you a clean gallery. The tile defaults to a comfortable 550×550 and is resizable like any node.

The one input

Just tag, default steps. It must match the tag on your GroupPreview emitters exactly - case-sensitive, no fuzziness. That's the only thing you set, and it's also the only thing that can go wrong. The node has no other inputs and no outputs, which is precisely what makes it safe to park anywhere.

Install

It ships in the comfyui-floating-preview pack. Via ComfyUI Manager, search "floating preview", or clone it:

cd ComfyUI/custom_nodes
git clone https://github.com/automatasz/comfyui-floating-preview

then restart ComfyUI. No model downloads, no extra Python dependencies beyond Pillow (already in ComfyUI). One warning: the pack's README is stale and its install snippet still points at the upstream chrisgoringe/cg-previewer repo this pack descends from - use the URL above.

Common issues

Empty gallery almost always means a tag mismatch - check that the display's tag and your emitters' tag are identical strings. Remember the gallery resets every run: if you were hoping to keep run #1's images on screen to compare against run #2, that's not what this node does; snapshot the tile or save your images to disk if you need side-by-side. And don't confuse this with the pack's floating preview window - that one shows whichever node's preview is currently running, full-size. This one is the gallery, for seeing many outputs at once. They complement each other; for pure "watch one image get bigger as it renders," the floating window wins.