Brightness

Here's the thing nobody tells you about this node: it can only make an image brighter. The factor widget is clamped to 0–1, and 0 means "no change." If you came here to darken a too-bright render, you're in the wrong node - that's what the Gamma node from this same pack is for. Brightness is the "add light" tool. Knowing that one limitation up front saves you a frustrating ten minutes.

How it works

It wraps Kornia's adjust_brightness, which uses the additive (Szeliski) convention:

out = image + factor

It literally adds the factor to every pixel, then clamps the result to [0, 1]. That's the whole mechanism - there's no curve, no perception trick, just a flat shift. factor = 0 is identity; factor = 0.05 is a gentle lift; factor = 0.1 already pushes toward clipping. Because it's additive, the trade-off is brutal: brighten enough to rescue a dark image and your highlights will blow out into flat white. Kornia's own docs warn about exactly this and suggest gamma instead when you want a softer effect.

The inputs

• images - a ComfyUI IMAGE, straight off the VAE or anywhere mid-pipeline.
• factor (0–1, default 0) - the only dial. 0 = unchanged; small values are your friend.

Output is an IMAGE of identical resolution, wired onward like any other node. That's the entire surface area of it.

Installing it

It comes with the ImageProcessing pack by bvhari, seven small wrappers over the Kornia library:

cd ComfyUI/custom_nodes
git clone https://github.com/bvhari/ComfyUI_ImageProcessing
# restart ComfyUI; kornia auto-installs from requirements.txt

Or via ComfyUI Manager → search "ImageProcessing" → Install → restart. Find it under the ImageProcessing category. No models, no keys, and like the rest of the pack it does its work on CPU - trivial for one image, mildly slow for a big batch.

When it bites

The main trap is the one-way direction, already covered. The second is clipping: brightening is a hard additive shift, so mid-tones go milky and whites die before the dark stuff even catches up. If your image needs depth rather than more light, use Gamma. And while kornia's underlying function technically accepts negative factors (which would darken), the node widget won't let you type one - don't fight it, just reach for the right node. Missing-module error on startup? pip install kornia into your ComfyUI environment and restart.