🟫 CR Halftone Grid

This one builds a halftone dot pattern from scratch - a grid of dots whose size ramps across the canvas following a color gradient. Think pop-art backgrounds, comic-book textures, retro-print overlays, that Roy-Lichtenstein dotted look you can drop behind a subject or multiply over a render. It's a pattern generator, not a filter, so it doesn't take an input image; it makes one.

It lives in Comfyroll Studio, the sprawling utility pack from Suzie1 and RockOfFire. Purely graphical, no GPU, no model.

How it works

You give it a canvas size and a dot_style, and it draws dots that grow and shrink according to that style's gradient, radiating from a center point you set with x_pos / y_pos. The dot styles aren't Comfyroll inventions - they're matplotlib colormaps (82 of them: viridis, Blues, bone, Accent, bwr, and so on). That detail matters for install, more below.

The inputs that matter

• width / height - output canvas.
• dot_style - the colormap that drives the dot gradient. reverse_dot_style flips it.
• dot_frequency - how many dots across (1–200). Low = big chunky dots, high = fine grain.
• x_pos / y_pos - the 0–1 center of the gradient. Move it to shift where the dots are biggest.
• background_color - named-color dropdown; set it to custom to unlock the optional bg_color_hex input (a named color ignores hex - the standard Comfyroll gotcha).

Output is a single IMAGE plus the usual show_help string (a wiki link, leave it dangling). Feed the image into a blend/composite node, or straight to a preview to dial it in.

Installing it

Via ComfyUI Manager: search Comfyroll Studio, install, restart. Or by hand:

cd ComfyUI/custom_nodes
git clone https://github.com/Suzie1/ComfyUI_Comfyroll_CustomNodes

then restart. No models to download.

Common issues

The whole Comfyroll pack won't load - and this node is the reason it shows up in the error. The classic failure looks like this in the console:

Comfyroll Studio: Failed to load Graphics nodes
NameError: name 'CR_HalftoneGrid' is not defined

That CR_HalftoneGrid is this node. What actually happened is a graphics dependency didn't import - most often matplotlib (remember, the dot styles are matplotlib colormaps), sometimes the wider scientific stack. When that import dies, the class never gets defined, and the pack's node-mapping file blows up on the first line that references it, taking the entire pack down with it. So a missing matplotlib doesn't just break Halftone Grid - it hides every Comfyroll node.

The fix: scroll up to the first traceback (the real ImportError), then install the missing library into the same Python ComfyUI runs. On Windows portable that's the embedded interpreter:

python_embeded\python.exe -m pip install matplotlib

then restart. People hit this on clean installs in early 2025, so it's not exotic - it's the pack's most reported install snag.

Dots too coarse or too fine. That's dot_frequency - nudge it rather than changing size elsewhere.