LC Lift Gamma Gain

Color graders think in lift, gamma, and gain: shadows, midtones, highlights, each adjustable without wrecking the others. A brightness slider shifts everything and clips fast; a lift/gamma/gain grade reaches into one tonal zone at a time. LC Lift Gamma Gain brings that classic color-wheel structure to ComfyUI as a deterministic post-process - no model, no re-generation, just a grade that looks like someone actually opened the image in a proper editor.

How it works

The math is the classic film formula, applied per channel in linear light: ((x + lift)^gamma) * gain + offset. The node decodes the image from sRGB to linear before grading and encodes it back after - which is the detail that separates a real-looking grade from a washed-out one. Each control owns a tonal range:

• lift (−1 to 1, default 0.01) - tilts the shadows. Negative crushes blacks, positive raises them into grey.
• gamma (0.1–4, default 1) - the midtone curve. Below 1 lifts mids, above 1 darkens them, without moving black or white.
• gain (0–4, default 0.9) - scales the highlights. Push it up to open bright areas, pull it down to tame blown skies.
• offset (−0.5 to 0.5) - a plain additive shift across the whole frame, for a flat cast that isn't tied to any zone.
• strength (0–1, default 0.5) - blends the grade back toward the original, so you can apply half a grade and keep things subtle.

The single image output comes with the pack's hover-to-wipe preview, which matters here more than usual - lift/gamma/gain is easy to overshoot, and the wipe is how you'll catch it.

The few controls you'll actually ride

Set strength first and think of it as your global budget. Then: gamma for "this looks flat / this looks crushed," gain for "highlights are too hot," lift for "the blacks have no life." That covers 90% of casual grading. offset is the one beginners lean on too hard - it's additive, so it washes contrast; use it sparingly.

Install

Ships in ComfyUI LC123 Nodes (MIT, 89 nodes). ComfyUI Manager → search "ComfyUI LC123 Nodes", or:

cd ComfyUI/custom_nodes
git clone https://github.com/lonecatone23/ComfyUI_LC123_nodes

Restart. No extra dependencies or model downloads. On hosted platforms like RunningHub, have the platform install the pack for you.

Where it sits in a workflow

This is the "before img2img" node: when an image is just off, a tone grade beats a regeneration that might rewrite the whole face. It slots after the sampler and before save, or mid-pipeline before an upscale. If you want the same idea with per-channel color wheels (tint the shadows blue, the highlights warm), that's the territory of the pack's LC Image RGB for flat offsets - but for zone-aware grading, this is the one.