ScarlotSoft Image Compare

A/B testing is how you find out whether that sampler change mattered. ScarlotSoft Image Compare is a preview node purpose-built for it: two IMAGE inputs, and on the canvas it renders a side-by-side comparison you can scrub - a split slider that reveals one image or the other as you drag, plus modes to show just image 1 or just image 2. It's an output node, so it produces nothing downstream; its entire job is to let you eyeball two results.

The important design decision the author made: the images are not resized or rescaled to match. It grabs the first frame of each input batch and displays them at their true resolution. That's the honest way to compare - the moment a compare tool letterboxes one image to match the other, it's quietly lying about what each pipeline produced. The node saves both to ComfyUI's temp folder (with a random filename each run, so no stale-cache surprises) and the frontend loads them into the interactive widget. Two inputs, zero outputs, OUTPUT_NODE = True; that's the whole schema.

Where you'll reach for it: before/after a detailer pass, seed A versus seed B, one upscaler against another, or your current run against the reference image you're chasing. Because it just takes IMAGE sockets, you can tap any output in the graph - put it at the end of two divergent branches and the split view tells you in one glance which branch wins. It doesn't save a file for you (the suite's Save Image handles that); it's purely an on-canvas inspection tool. Keep in mind it only compares the first frame of each batch - comparing frame 3 of two videos needs a From Batch node in front of each input.

Install as part of the suite - ComfyUI Manager → search ScarlotSoft → install → restart, or:

cd ComfyUI/custom_nodes
git clone https://github.com/scarlotsoft/ComfyUI_ScarlotSoft

No dependencies, no models. Suite theme; hard-refresh (Ctrl+Shift+R) if the canvas looks off after a UI-mode switch.

Honest comparison to the alternatives: ComfyUI's core ImageCompare node is basically a button that opens a separate browser window with the images stacked - functional, but you leave the canvas. Third-party compare widgets exist but they're usually married to a bigger pack. This one keeps the comparison on the canvas with a scrub slider, which is genuinely nicer for iterating quickly. Is it a reason to install the whole pack alone? Marginal - but if you're in the pack, it's the node you'll leave hanging off your workflows to keep honest about whether the last tweak helped.