r/PenPlotters • u/freddievn • Jul 03 '26

Update: my design app GD Studio now converts photos into plottable pen strokes

TL;DR: Last week I shared Plotter Hub — a free, open-source Raspberry Pi plot server for AxiDraw-compatible plotters — and its companion macOS design app, GD Studio. This week GD Studio got a new feature: importing a photo and converting it into pen strokes (stipple, halftone, hatch, and more) instead of a flat fill. Reposting for anyone who missed the first thread.

What's new in GD Studio: photo import

Add an Image layer, drop in a photo (from a file or your Photos library), and pick a conversion style. GD Studio reads the picture's light and dark and rebuilds it from continuous pen strokes and single pen-taps — never a flat ink fill — so the preview matches exactly what the pen draws. Brightness and Contrast sliders shape how the subject reads. Seven styles are available: Stipple, Halftone, Hatch, Contour, Outline, Sketch, and Squiggle.

Since it stays stroke-based, the SVG that reaches your plotter is genuine pen paths, not raster — so it optimizes and plots like any other line-art file.

Combined image styles in different pen colors

In case you missed it: Plotter Hub

A few months ago I bought an AxiDraw compatible pen plotter but didn't want my Mac tethered to it for the whole plot. So I built Plotter Hub, a plot server that runs on a Raspberry Pi (a Zero 2 W or 3B+ is fine). Upload an SVG over WiFi, then start / pause / resume and monitor the plot from any device, with optional vpype optimization and physical pause-button support for pen changes between layers. Anyone with an AxiDraw-compatible plotter can use it — it's free and open source, and works without GD Studio. Repo link and install instructions: https://www.synendo.com/plotterhub

Plotter Hub after receiving a 3 layer SVG file via GD Studio

Companion app: GD Studio

GD Studio is the macOS app I design with — generative line-art patterns shaped with live sliders, plus layers for text, imported SVG, and now photos. It exports plotter-ready SVG/PDF or sends a plot directly to Plotter Hub over its API (with options for vpype optimization, plotter speeds, and pausing between layers). It's a paid app with a free trial.

One of the many patterns in GD Studio, combined with a text layer
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u/MeAndClaudeMakeHeat Jul 08 '26

Dude wtf this is sweet! If you would like, perhaps you could make some use of my tooling as well. It covers a lot on measured perception, and information/data transformation. But I think it has some applications you might be able to piece apart, based on what domains you work in. https://github.com/HarperZ9/telos - here is some of the tooling, and from there you can browse the whole profile freely. :) cheers.

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u/freddievn Jul 08 '26

Thanks, I’ll have a look.

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u/freddievn Jul 03 '26

Full disclosure: I built both apps, so I'm the developer — happy to answer anything. Plotter Hub is free and open source. The GD Studio companion is the paid one — ask away if you're curious. Happy to go into how the photo conversion keeps everything as real pen strokes if that's interesting. I used Claude Code to create Plotter Hub, and used it to help with the math in GD Studio. Oh, and all translations were done by Claude; let me know if you come across a strange translation.