Image Comparer ⚖️

When you're A/B testing - two samplers, two CFG values, two LoRA stacks - the honest way to judge is to flip between the images at the same zoom and pixel position, not squint at two thumbnails side by side. IkkiImageComparer is a preview node that gives you a slide-to-compare widget right on the node: drag your mouse across the image and it wipes between the two, so you see the difference exactly where it happens. Think of the slide-to-compare in rgthree's comparer, which the ecosystem doc notes people lean on constantly - this is the same idea from the Ikki pack.

Under the hood it's a subclass of ComfyUI's own PreviewImage node with a custom frontend widget. It takes two optional image inputs, image_a and image_b, saves both as previews, and the widget handles the rendering. It's an output node - nothing downstream needs to consume it, it exists to be looked at.

Using it

• Drop it at the end of two alternative branches of your workflow. Wire the first branch to image_a, the second to image_b. In slider mode, moving the pointer across the node reveals image_b; in Click mode, hold the mouse button to swap. There's a comparer_mode property on the node to switch between them.
• The single images output just returns whatever came in, so you can keep a SaveImage node downstream if you also want to export the result.
• Because each input is optional, you can even use it as a single preview - though at that point the regular PreviewImage does the job.

Install

The pack installs via ComfyUI Manager (search "ikki") or:

cd ComfyUI/custom_nodes
git clone https://github.com/RedsAnalysis/comfyui-ikki-pack
# restart ComfyUI

No dependencies beyond core ComfyUI.

Things worth knowing

• The widget is custom canvas code. The same frontend that broke rgthree's comparer under ComfyUI's Nodes 2.0 rewrite can break this one. If you're on the new Vue-based canvas and the compare widget renders as a plain preview or nothing at all, that's the likely culprit - fall back to the legacy canvas, which the ecosystem doc notes is still the safe path through mid-2026.
• A vs B requires both inputs to be single images. The node trims to the first two previews; batches of ten will just show the first pair.
• It saves previews to ComfyUI's temp output area like any PreviewImage, so don't expect the "comparison" to be baked into a saved file - the interactivity is on the node, not in the PNG.

Honest take: this is a nice-to-have, not a must-install. If you already run rgthree and its comparer works for you, this adds nothing. But if you're building an A/B harness in the Ikki pack's own ecosystem, having the comparer here means one fewer pack to install - and it's zero-config, which the alternatives aren't always.