Image Contrast Adjuster

If you've generated a Krea2 storyboard grid and thought "why does this look so washed out," this is the node you want. Image Contrast Adjuster is a single-float-slider contrast grade, built by domg73 (MayaProphecy) as part of their ComfyUI-Storyboard-Tools pack for multi-panel Krea2 work. It does exactly one thing: takes an image in, gives you the same image back with a gently different contrast curve, no model downloads, no knobs to get lost in.

Krea2 is a strong cinematic renderer, but its open weights went through alignment training the API version didn't, and one documented side effect is flatter, softer output. When you're pushing a 3x2 grid of panels through a storyboard pipeline, a little per-panel contrast lift is the cheapest way to make everything read as intentional rather than muddy.

How it works

The math is about as simple as a custom node gets. Everything is a linear stretch around the 0.5 luminance midpoint:

soft_contrast = 1.0 + (contrast - 1.0) * 0.25
adjusted = clamp((image - 0.5) * soft_contrast + 0.5, 0, 1)

The detail worth knowing is the 0.25 factor. The slider goes 0.5 to 1.5, but the actual gain is dampened by four, so sliding to the max only gets you an effective multiplier of about 1.125x. That's deliberate - the author softens the curve so shadows don't slam into pure black the way a stock (pixel * k) contrast node will. You get a cinematic grade, not a crushed mess.

Inputs and outputs

Two things matter here:

• image - any IMAGE tensor, from a KSampler output, a loaded file, or straight off a StoryboardGridGenerator canvas.
• contrast - a float slider, default 1.0, range 0.5 to 1.5. Below 1.0 flattens, above 1.0 punches up. 1.0 is a pass-through, so the node is safe to leave inline.

The single output is an IMAGE of the same shape as the input. Wire it into a Save Image, a preview, or downstream into the next stage of your grade.

Install

Same story as the rest of the pack - this is one of the lightest installs in ComfyUI. No requirements.txt, no torch version pinning, just pure torch (which ComfyUI already ships). Grab it via ComfyUI Manager (search ComfyUI-Storyboard-Tools), or:

cd ComfyUI/custom_nodes
git clone https://github.com/domg73/ComfyUI-Storyboard-Tools

Then restart ComfyUI. It registers under the utils/storyboard category.

Gotchas

The dampened curve cuts both ways: if you're expecting a strong contrast punch, you'll be underwhelmed. Crank the slider to 1.5 and you'll still get a gentle lift - that's the design, not a bug. For genuinely punchy output you'd stack it with a curve or levels node elsewhere. And one workflow tip from the author's own posts: run it after cropping panels out of the grid, so each frame gets the same grade and the board reads as a unified piece instead of six separate exposures.