A Journey of Automatic Number Plate Recognition
0: Can't be that hard, right?
As a long-distance commuter for university, I see a lot of cars every day. Every since I was a small child, I had an obsession with license plates, so naturally, I have taken an interest in analysing the license plates I see on the Highway every day.
I should also be seeing the same cars every day. I am not the only one commuting on this route at that time on a schedule. And some obvious cars — a red Passat, cool license plates, weird window stickers — are easily recognised. But the more bland black sedans with incospicuous license plates I could probably not recognise as a known car.
And thats where I thought I might be able to combine that with my interest in a new tech project (as if I don't have enough already). I want a RPi to recognise license plates, create a database of them and give me statistics.
Automatic Number Plate Recognition (ANPR or ALPR) should be a long solved Problem. Every parking garage, toll booth and police car can already do it, so there are probably plenty of libraries out there that will just do it for me, right? Right!?
No
To be more precise: If you pay for it, of course.
There are commercial vendors, that will happily sell you a license to their software for only 30 grand a year. As a poor student, thats of course out of my budget.
There are plenty of projects out there, that try with different ways. In this blog series I will try to work through them and find something that works reliably.