Region Overlay Visualizer

This is the debugging eye of the Flux Region pipeline. It takes your finished image and lays the region layout on top of it, semi-transparent, so you can see exactly where each region landed relative to what the model actually painted. It's purely for looking - it doesn't change the generation - but when you're wrestling a multi-region Flux prompt into place, being able to see whether your left-region prompt actually stayed on the left is worth a lot.

Regional prompting is fiddly and the failure mode is subtle: attributes bleed a little, a region drifts, boundaries end up softer than you wanted. A visual overlay turns "hmm, something's off" into "ah, region 2 crept into region 1's space."

How it works

Two image inputs and a slider. You give it the image (your generated result) and a region_preview (the region layout image the earlier pipeline nodes produce), and it composites the second over the first at whatever opacity you set. Out comes a single blended IMAGE you can preview or save.

That's the entire mechanism - it's an overlay compositor with a fixed job. The author is explicit that it's "for visual purposes only," so don't expect it to feed back into the generation. Its place in the chain is the optional step right before Flux Attention Cleanup.

The inputs and outputs that matter

• image - your final render.
• region_preview - the region layout to overlay (from the generator/conditioning preview outputs).
• opacity - 0 to 1, default 0.3. Low so the underlying image still reads; bump it up when you want the region boundaries to pop.

The single output is IMAGE. Wire it into a Preview Image node and read your layout.

How to install it

ComfyUI Manager → ControlAltAI Nodes → install → restart, or:

cd ComfyUI/custom_nodes
git clone https://github.com/gseth/ControlAltAI-Nodes

then restart. No models, no dependencies for this node - it's an image blend. (The heavier XFormers requirement in this pipeline belongs to the Flux Attention Control node, not this one.)

Common issues

Basically none - it's a visualizer. The only thing to get right is feeding it the correct pair: the finished image and a matching region-preview image at the same dimensions, otherwise the overlay won't line up. If the overlay looks too faint to be useful, raise opacity; if it's drowning the image, lower it. And remember it's diagnostic only - it's an optional branch off the pipeline, so leaving it out doesn't affect your actual generation, it just means flying blind on region placement.