Fresco Overlay

Fresco Overlay answers one question honestly: did the picture land in the boxes you drew, or did the model wander off? It takes a render and the Fresco scene that produced it, and gives you the render back with every layer outlined, faintly filled and labelled.

It's a diagnostic, not a step in the pipeline. You don't need it to make images - you need it the first time two layers come out merged and you can't tell whether the boxes were wrong, the prompts were wrong, or a LoRA bled. This separates those cases in one glance.

The two inputs

image is the render - whatever your VAE Decode produced. fresco is the node the render was made from, i.e. the Fresco editor's fresco wire. Wire the same scene the sampler ran on and the outlines line up with what Fresco Apply was actually told.

One output: overlay, an IMAGE with every layer outlined. Send it to a Preview Image or Save Image and look at it before you touch anything else.

The trick worth knowing

There's a second behaviour hiding in here, and it's the one that makes the node more than a preview. If Fresco has no photo on it - a pure text-to-image scene - Overlay also sends the render back to the editor as its trace image, so the boxes sit over your last render while you adjust them. Trace image, in this context, means the picture the canvas shows underneath your layers.

Which means the loop is: draw, generate, overlay, and the render appears under the boxes so you can nudge them to match what you got. If you have a photo wired into Fresco Inputs, it keeps the photo instead - you're editing that, so masking over a render would be confusing.

If you want to keep a render as your trace permanently (rather than have the next run replace it), the editor has a pin for that.

Why it's separate from Fresco Apply

Fresco Apply already outputs regions, and the pack's Regions Preview shows the gate map - what the LoRA masks actually did during sampling. That's the post-sampling view of the mechanism. Overlay is the plain-language version: the boxes, on the pixels, with names on them. Different question, different node.

Install

Part of the same pack - search Nynxz in ComfyUI Manager, or:

comfy node install comfyui-nynxz-nodes

From source you have to build the frontend, or the Fresco editor itself won't render and there'll be nothing to draw on:

cd ComfyUI/custom_nodes
git clone https://github.com/Nynxz/ComfyUI-NynxzNodes
cd ComfyUI-NynxzNodes
pnpm install && pnpm build

Restart ComfyUI afterwards. No Python dependencies beyond what ComfyUI already installs.

When it looks wrong

Outlines sitting somewhere the subjects aren't: either the composition genuinely ignored the layout (raise layout_isolation on Fresco Apply, or give it a layout_start), or the render is a different aspect ratio from the canvas. That second one bites more often than you'd think - Fresco Apply has a one-click "match canvas" under the canvas for exactly this, and it's worth clicking before you conclude the model is misbehaving.

Overlay blank or empty: you wired a fresco from a different scene than the one that generated, or every layer is hidden. Hidden layers don't get outlined, on purpose.