HBH Image Preview

HBH_ImagePreview is the pack's equivalent of a "show me what's on this wire" terminal. You feed it an IMAGE and it displays it - that's it. No outputs, nothing saved to disk, no processing. It's an output node that exists purely so you can look at a result mid-graph without littering your output folder with files.

The mechanism is almost suspiciously simple. It's marked OUTPUT_NODE = True, takes a single image input, and its preview function returns an empty dict - it doesn't even pass the image along, because it doesn't need to; ComfyUI displays the input of an output node as its preview. The one notable behavior: IS_CHANGED returns NaN, which forces the node to re-execute on every queue run. That's the "refuses to sleep" part - unlike a plain reroute that skips when nothing changed upstream, this one always refreshes, so the preview stays honest even if you're just re-running a graph to check intermediate state.

Where it earns its keep: debugging branches. Plop one at the end of any image path and you get a live look without committing anything to disk or having to swap in a PreviewImage. It's also useful at the end of a coordinate or overlay chain - see the composited result, and if it's wrong, fix and re-run without the output folder filling up with junk.

Honest context: it's a trivial node, and ComfyUI's core PreviewImage already does most of this - the meaningful difference is that this one writes nothing and always re-runs. If you're allergic to stray PNGs, that's a real advantage; if you need to save the result, use SaveImage instead. There's no reason to build a workflow around it, but it's a reasonable stand-in inside this pack's own example graphs.

Install is the same as the rest of the pack:

cd ComfyUI/custom_nodes
git clone https://github.com/wings6407/ComfyUI_HBH-image_overlay

or via ComfyUI Manager (search ComfyUI_HBH-image_overlay), then restart. No requirements.txt, no model downloads - just numpy, torch and Pillow already present.

Pack-level caveats apply: solo dev, a single commit, zero community discussion. For a node this simple that's fine - there isn't much that can break. If the preview ever looks stale, that's usually ComfyUI's browser cache, not this node.