color_OneColor_keep

This is the old "red rose on a black-and-white photo" trick. color_OneColor_keep desaturates everything in the image except one chosen color, which stays in color - and can even get boosted past its original saturation. It's a strong, dated-looking effect if you crank it, but used with a light touch it reads as a tasteful selective-color grade instead of a 2008 Photoshop tutorial. It's under Apt_Preset/image/color_adjust.

How it works

Pixels close to color (within falloff's tolerance) get preserved and boosted by gain; everything else gets desaturated to gray. It's a straightforward isolate-and-boost operation, not a full selective color-grading tool - one color range in, everything else out.

The inputs and outputs that matter

• color (hex, default #000000) - worth flagging: the default is black, which is not a useful starting point since almost nothing in a real photo is pure black. Set this to whatever color you actually want to keep before doing anything else.
• falloff (0-100, default 30) - how wide a tolerance around color counts as "keep." Treat it as a threshold, not a percentage of the image.
• gain (0-10, default 1.5) - boosts saturation/vibrance of the kept color range once isolated, so the surviving color can end up more saturated than it was in the source.
• image in (optional in the schema, but you'll want one wired for the node to do anything), image out.

How to install it

Through ComfyUI Manager: search "ComfyUI-Apt_Preset", install, restart. Manually:

cd ComfyUI/custom_nodes
git clone https://github.com/cardenluo/ComfyUI-Apt_Preset.git

then run install.bat (Windows) or install requirements manually on Linux/Mac, and restart. No model downloads for this node.

Common issues & troubleshooting

Output is fully gray. The most likely first mistake: color is still at its #000000 default. Change it to the actual color you want kept.

The kept color bleeds into areas you didn't want. Lower falloff to tighten the tolerance around your chosen color.

Effect looks too intense / retro. That's gain pushed too far above its 1.5 default - pull it back toward 1 for a more natural-looking pop instead of a maxed-out one.

Want to swap the surviving color instead of just isolating it? Pair this with color_OneColor_replace, the companion node in this pack for exactly that.

IMPORT FAILED on the pack. ComfyUI-Apt_Preset is large and updates often; users have reported import failures after some updates. Reinstall via Manager before assuming it's this node.