Two algorithms, one outcome.
Residual (default): constructive least-squares, robust to contrast and brightness. Legacy: original greedy solver, compatible with the Python prototype.
In focus · Lineon
Lineon
From a photo to a finished build guide — Lineon computes which nails to wrap in which order and ships a printable step-by-step PDF. iOS, Android, Web. No account, no tracking.
Web app
Open it straight in the browser.
No install, no account. Pick a photo, confirm the crop, generate — the web version computes entirely client-side. After payment, a 72-hour window lets you re-export the PDF if anything goes wrong on print.
Overview
Photo in. Build guide out.
Lineon takes your photo, crops it to a circle, computes on-device and produces a printable PDF: materials list, 1:1 nail-layout diagram, wrap-by-wrap table with checkboxes. Mobile is a one-time in-app purchase; Web is pay-per-image via PayPal — Lifetime is native-only.
Features
What Lineon does — and why.
Every feature serves one outcome: a tensioned thread piece on a wooden board on the wall — no plot, no toy.
Nail density and string count.
Nails 120–500 pins, strings 200–3000 lines. Default 360 / 1600 — sized for a 60 cm board. Sliders for contrast and brightness.
30 / 40 / 50 / 60 cm — or freeform.
Before each PDF export you pick the physical board size in 10 cm steps between 10 and 200 cm. The materials list and layout diagram adapt automatically.
Cover to tips — everything in one print.
Cover, stats, materials list, nail-layout diagram, wrap instructions with checkboxes (3-column staggered for long lists) and a tips chapter on tension management.
One codebase, three platforms.
Flutter native for iOS and Android, Flutter Web for the browser. Feature parity; payment differs per platform.
Native one-shot, web per image.
Native: €2.99 per PDF export, €29.99 lifetime unlock (App Store / Play Billing). Web: pay per original image, 72-hour re-export window via PayPal — no account.
No images held by us.
Native: fully on-device. Web: we only store an anonymous HMAC fingerprint of your image — no originals, no PDFs, no PayPal IDs in our database.
Open-source friendly.
All dependencies BSD / MIT / Apache 2.0 / SIL OFL — no proprietary lock-in. Project itself MIT-friendly.
Lineon
Technical specs.
| Platforms | iOS · Android · Web |
|---|---|
| Default config | 360 nails · 1600 strings · 60 cm board |
| Nail / string range | 120–500 pins · 200–3000 lines |
| Board sizes | 30, 40, 50, 60 cm preset — or freely chosen in 10 cm steps |
| Native pricing | €2.99 per PDF · €29.99 lifetime (Apple IAP / Play Billing) |
| Web pricing | Pay-per-image via PayPal · 72 h re-export window · max 5 exports |
| Data | Native: on-device · Web: anonymous HMAC fingerprint only |
| Web hosting | lineon.qorvano.com · IONOS Germany · Caddy + Python backend |
FAQ
Common questions.
What's the difference between web and native?
Feature parity. Native runs entirely on your device and offers a lifetime unlock; web runs in your browser, also computes client-side, but has no lifetime model — you pay per original image and may re-export the resulting PDF up to five times within 72 hours, in case something goes wrong on print.
What data do you store about me?
Native app: none. Web variant: an anonymous HMAC fingerprint of the original image, a timestamp and an export counter — no images, no PDFs, no PayPal order IDs. Recovery works by re-uploading the same image within the 72-hour window.
Which board sizes are supported?
Presets at 30, 40, 50, 60 cm diameter; freely chosen in 10 cm steps between 10 and 200 cm. The materials list and nail-layout diagram in the PDF adapt automatically.
How many nails and strings make sense?
Default 360 nails and 1600 strings work for most photos on a 60 cm board. More nails mean finer resolution but higher cost and longer build time. More strings mean a darker piece — past about 2500 strings the motif starts to blur.
Which solver is better?
Residual is the default and the right choice 90 % of the time — it is robust against over- or underexposed photos. Legacy greedy stays in for comparisons and for photos with very clearly drawn faces, where the older algorithm sometimes gives cleaner outlines.
Do I need an account?
No. Native apps run without one; purchases run through Apple IAP or Google Play Billing and are tied to your Apple ID / Google account. Web is anonymous — payment via PayPal, no registration.
Can I use Lineon commercially?
Yes. The generated build guides are yours; you may sell the finished string-art pieces. The app itself and the algorithm may not be reverse-engineered, copied or resold — see the EULA.
What happens if the web variant ever shuts down?
Web is not designed for lifetime — hosting costs for a paid image are priced in plus a small reserve. Native apps keep working independently of the web service. For long-term use, choose the native lifetime unlock.
Support
Questions about Lineon or about printing?
If something doesn't work or you miss a feature, write to us. We reply personally, usually within a few business days.