My girlfriend loves paint by numbers apps so I did what any unhinged developer would do  I spent 3 months building her one from scratch.

You take any photo, my algorithm converts it into a paint by numbers canvas, and then you can complete it right there in the app. No ads, no paywalls, completely free. 

The part I'm most proud of is the conversion algorithm —getting it to produce clean, paintable regions with the right level of detail without it looking like a mess took way longer than I expected. Happy to get into the weeds on how it works if anyone's curious. It relies, on a lot of tricks likes detecting the subject and processing that separately from the background, using Ai line detection to make pieces make more sense, and smartly merging pieces based on certain criteria.

**What I'm building next:**

* Print-to-paper support so you can do it IRL
* A reveal feature where photos stay hidden behind the canvas until someone actually completes the painting (send your friends a portrait they have to paint to see)

It started as a gift and now I kind of want to see how far I can take it.

What would you add? Always looking for an excuse to keep building.

I vibe coded a paint by numbers app for my girlfriend