RC Brightness/Contrast

Every image editor has a brightness/contrast slider, and none of them are exciting. RC Brightness/Contrast is exactly what the name says - which is the point. In a ComfyUI graph you don't always need a curves node with a fancy interactive editor; sometimes you just need to lift a dark render a couple of stops and add a touch of snap. This is that node, and it does the job without drama.

It's part of the RC Image Compositor pack, the Photoshop-style toolkit that keeps turning up in compositing workflows. This particular node is the dependable utility you reach for when you want a quick, predictable global adjustment before or after other processing.

How it works

The one thing that separates it from the pack's other adjustment nodes is the method choice:

• OpenCV - the default. The tooltip calls it "more precise," and it is: OpenCV's addWeighted-style math gives a cleaner, more linear response curve.
• PIL - the classic Pillow ImageEnhance approach, which historically uses a different formula that lifts blacks a bit more aggressively.

In practice the difference is subtle on most images, but on low-key shots or anything with deep shadows, OpenCV keeps your blacks blacker while PIL can gray them out. If your renders come out looking slightly washed when you boost brightness, try flipping to OpenCV first.

The inputs that matter

• image - the input tensor.
• brightness - −100 to 100, negatives darken. Small numbers do real work; ±20 is a lot.
• contrast - −100 to 100. Negative flattens the image, positive adds snap.
• method - PIL or OpenCV, as above.

Output is a single IMAGE tensor, so you can chain it into a save, another adjustment, or a compositor.

How to install it

Ships with the RC Image Compositor pack:

cd ComfyUI/custom_nodes
git clone https://github.com/kj863257/ComfyUI_RC_Image_Compositor
cd ComfyUI_RC_Image_Compositor
pip install -r requirements.txt

Then restart ComfyUI. ComfyUI Manager users: search "RC Image Compositor". Only pillow, numpy, and opencv-python are required - all things you already have if ComfyUI runs at all.

Common issues

The classic mistake is cranking brightness when what you actually need is curves or levels. Brightness shifts the whole image up, which pushes black points toward gray and flattens contrast even as it lightens. If your "too dark" image has fine shadow detail you want to preserve, you'd be better off with the pack's RC Curves or RC Levels node, or RC Auto Color Correction's shadow/highlight clipping, which stretches without wrecking the blacks.

And a fairness note: this is a two-slider global adjustment. It won't rescue a blown highlight or fix a color cast - reach for RC Color Match or RC Color Balance for those. Brightness/contrast is a blunt instrument, used early and often, and it's all the better for knowing its limits.