Contrast

Sometimes you don't need a full color-grading suite in your graph, you just need to punch up (or flatten) the contrast on an image before it hits a Save node or a comparison grid. ContrastNode does exactly that one thing: it's a single IMAGE in, one factor knob, one IMAGE out.

It ships inside ComfyUI-LogicUtils, a small utility pack from GitHub user aria1th - publicly known as AngelBottomless, the trainer behind Illustrious XL, one of the most widely fine-tuned anime SDXL checkpoints in the open ecosystem. LogicUtils itself isn't a generation pack - it's a bag of general-purpose glue nodes (image ops, dict manipulation, type conversion) that reads like something built for personal batch-processing pipelines rather than a polished public tool. The README's own description sets the tone: "proper documentation is being prepared, however there are too many nodes."

How it works

It's a straightforward contrast adjustment applied to whatever image you feed it. The factor input is the multiplier: a value of 1 leaves the image unchanged (that's the default), pushing it higher increases contrast - darks get darker, lights get lighter - and pushing it below 1 flattens the image toward flat grey. There's nothing more exotic going on than that; this is the kind of quick post-processing step you'd otherwise reach for an external image editor to do, done in-graph so it's part of your reproducible pipeline instead of a manual step you have to remember to redo.

The inputs and outputs that matter

• image (IMAGE, required) - the image to adjust.
• factor (FLOAT, default 1) - the only knob. 1 is neutral, higher sharpens contrast, lower flattens it. This is genuinely the whole interface.
• Output: a single IMAGE, ready to wire into a Save Image, Preview Image, or another processing node.

How to install it

Through ComfyUI Manager: search ComfyUI-LogicUtils, install, restart the app. Or by hand:

cd ComfyUI/custom_nodes
git clone https://github.com/aria1th/ComfyUI-LogicUtils

Restart ComfyUI once it's cloned. No models to fetch - this is a plain image-processing operation, nothing that needs a checkpoint or a large download. The README mentions an opt-in auto-install hook (COMFYUI_LOGICUTILS_AUTO_INSTALL=1) and a way to disable it outright (COMFYUI_LOGICUTILS_SKIP_INSTALL=1), but a simple contrast node like this one has no extra dependencies that hook would need to handle.

Common issues & troubleshooting

The effect looks way stronger or weaker than expected. Because factor is an unbounded multiplier rather than a normalized 0–1 slider, small changes can have an outsized visual effect at the extremes. Nudge it in small steps from 1 rather than jumping straight to a big number.

Image comes out looking washed out or near-solid grey. You're likely below 1 - that direction pushes toward flat grey rather than toward black. If you wanted more punch, not less, you want a value above 1, not below it.

Can't find the pack in ComfyUI Manager. It's a low-visibility repo, easy for the search index to miss. Use Manager's "Install via Git URL" option and paste https://github.com/aria1th/ComfyUI-LogicUtils directly if the normal search doesn't surface it.

No response on a GitHub issue. Worth setting expectations here: this is a personal utility repo from someone whose public work shifted away from image-generation tooling in early 2026, not an actively supported product. For a node this simple, though, you're unlikely to need support - if the output doesn't look right, it's almost certainly the factor value, not a bug.