Color Grading JK🐉

A generation that's technically fine but slightly off - too dark, washed out, green-tinted - is the most common reason an image misses. Color Grading JK is a quick global pass to fix exactly that: brightness, contrast, saturation, plus per-channel RGB offsets. It's not a LUT, it's not film emulation; it's the four knobs that fix 90% of "why does this look wrong" complaints.

How it works

The node runs PIL's ImageEnhance for the first three controls, then does a per-channel offset for the RGB ones.

• brightness - a multiplier, default 1.0, range 0–3. 1.0 is neutral.
• contrast - a multiplier, default 1.0, range 0–3.
• saturation - a multiplier, default 1.0, range 0–3.
• R, G, B - additive offsets, default 0, range −255 to 255.

Note the two different semantics living on one node: brightness/contrast/saturation are factors (1.0 = do nothing), while R/G/B are offsets (0 = do nothing). Mixing them up is the classic first mistake - setting saturation to 0 doesn't make it neutral, it makes the image fully grayscale.

The channel offsets are useful for cast correction. A blue-ish render gets B nudged negative; a green cast from certain lighting gets G pulled down. Because they're simple additive shifts, they're blunt instruments - fine for neutralizing a cast, wrong for creative color grading. The node preserves the alpha channel if your input is RGBA, so you can grade layered images without losing transparency.

Inputs and outputs

• image - the input IMAGE.
• brightness, contrast, saturation - the three factor knobs.
• R, G, B - the three channel offsets.
• IMAGE - the graded result.

Batch-wise it processes every image in the input tensor with the same settings, which is exactly what you want when color-matching a sequence or a batch of variant renders.

Installing it

Ships in ComfyUI-JakeUpgrade:

• ComfyUI Manager → search "JakeUpgrade" → install → restart.
• Or:

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

Windows portable: run install.bat or ../../../python_embeded/python.exe -s -m pip install -r requirements.txt.

Common issues

• Saturation 0 isn't neutral. It's grayscale. Neutral is 1.0. Same for brightness and contrast - the defaults are all 1.0, and any value you type replaces them, not adds to them.
• R/G/B go negative fine. Offsets range −255 to 255; a negative value subtracts from that channel. You're not limited to boosting.
• It's a global pass, not a masked one. No region control here. For selective grading you'd composite this with a mask or reach for a heavier color node.
• Cast correction overshoot. Additive offsets can clip channels at 0 or 255, blowing out highlights. Small nudges (10–30) beat big ones.

This is the "one more node before the save" that makes a render look finished instead of raw. It's also the node JakeUpgrade uses internally in its long-video workflows to keep color consistent across segments - a sign it's reliable enough to trust on a sequence, not just a single frame.