NO8D-A/B preview

You've got two generations you want to compare - a LoRA at 0.8 vs 1.0, a Krea 2 prompt with and without the style card, denoise 0.4 vs 0.6. The default ComfyUI move is two Preview Image nodes and a lot of neck craning. NO8D-A/B preview is the version of that which lets you actually look: it shows both image streams side by side with a draggable split slider, so you can scrub between A and B and see the difference where it matters instead of guessing.

Small honesty note: the "preview" does the heavy lifting here. The node itself is thin - it hands both branches to ComfyUI's built-in PreviewImage and passes the tensors through. The clever part is the frontend, which renders the two streams as an interactive split. You feed it, it displays, and the comparison is up to your eyes.

What you actually set

• image_a and image_b - the two IMAGE streams. Wire anything that outputs an image into each. They're both optional, so you can use this as a glorified viewer for one branch if you want.
• auto_output - the only real control, default on. When it's on, the image_a output passes A through to whatever comes next. Flip it off and the A output is blocked (ComfyUI's ExecutionBlocker), which is the "auto-output switch" the README mentions. Image B always passes through. This is how you keep one of the two branches from also feeding a Save node or a sampler while the other one does.

Outputs are image_a and image_b, both IMAGE. Wire whichever one you're keeping into your Save Image, or leave the node as the visual end of the line.

Why it earns its slot

This is a quality-of-life node, and it's worth having for the workflow hygiene alone. Because it passes both streams through while displaying them, you can keep the comparison in the graph without doubling your Preview nodes, and the split view catches things a full-screen compare misses - edges, skin texture, the way a face drifts between two seeds. It's the kind of node you reach for mid-iteration, when you're dialing in a strength or a CFG and want the difference under a slider rather than across a screenshot.

Install and troubleshooting

The pack is no8d/ComfyUI-NO8D-controls - install it once, and all the NO8D nodes come with it. In ComfyUI Manager, search "NO8D-controls" and hit install, or:

cd ComfyUI/custom_nodes
git clone https://github.com/no8d/ComfyUI-NO8D-controls.git
cd ComfyUI-NO8D-controls
python -m pip install -r requirements.txt

Dependencies are light - just openpyxl and json-repair - and there are no model downloads for this node. Restart ComfyUI and hard-refresh the browser so the frontend JS loads.

The one thing that trips people: because the A output gets blocked when auto_output is off, a downstream node wired to A will silently stop producing output. That's the feature, not a bug - if your graph goes dark on one branch, check the toggle before you blame the upstream sampler.

Install notes that apply to every NO8D node

Everything in this pack installs the same way, needs nothing beyond openpyxl and json-repair, and has no model files to fetch. If you're here for this node, you've already got the whole pack.