ColorMod (move)

ColorMod (move) adds a constant amount to every pixel. That's it. No curve, no math to learn, no model - it's just "make the whole image brighter by this much" with a single slider. It sounds too simple to be a real node, and that's exactly why it's useful: when you want the whole image one step brighter and you don't want to re-roll a seed or fight a KSampler, this is the one-call way to do it.

It's the simplest node in city96's ColorMod pack, and it also happens to be the building block of the pack's HDR workflow - because it's one of the cleanest ways to produce the "same scene, different brightness" passes you feed into Create HDR image.

The inputs

• move (default 0.0, range −1 to 1) - the offset added to every channel of every pixel. Positive brightens, negative darkens. A move of +1.0 with clipping on means "everything becomes white," so treat the extremes with respect.
• clip (default True) - whether to clamp the result to [0, 1].
• image in, one IMAGE out.

The clip toggle is the whole interesting part of this node. On (the default), values get clamped to [0, 1], which is what you want before a VAE or sampler - out-of-range values can make diffusion models do odd things. Off, and the shift can push pixels above 1 or below 0, which is exactly what you want when you're generating HDR passes: brighter than white is the whole point there.

The visualization

Like every ColorMod node, this one draws a little canvas showing what it does: the transfer function plotted as a line from bottom-left to top-right. Default is a straight diagonal; slide move and the line shifts up or down. Input values run along the bottom, remapped values up the side - so you can see "this much brighter" before you run the graph. It's a nice touch from a pack that usually leaves you to guess.

Installing

cd ComfyUI/custom_nodes
git clone https://github.com/city96/ComfyUI_ColorMod
cd ComfyUI_ColorMod
pip install -r requirements.txt

Restart, or install via ComfyUI Manager ("ComfyUI_ColorMod"). Unlike the 16-bit and HDR nodes, this one has no dependencies - it's pure PyTorch, so it works even if you never install pypng or opencv.

Where it fits

• Quick global brightness fix before saving.
• Generating HDR source passes: clone your image three times, apply different move values with clip off, feed them into Create HDR image. Remember the README's tip: if the passes drift, keep them aligned with ControlNet.
• When the brighter version needs to stay "in range" for the VAE, leave clip on.

There's no tonemap hidden in here, no color science - if you need shadows and highlights to move differently, use ColorMod (move pivot) or ColorMod (edges) instead. But for a straight lift or dip, this is the one.