OpenALPR: Automatic License Plate Recognition Library | Hacker News Reader

OpenALPR: Automatic License Plate Recognition Library

github.com

44 pointstrymas15 comments

> -c <country_code>, --country <country_code> Country code to identify (either us for USA or eu for Europe). Default=us

Europe is not a country, it's a continent with multiples countries, each one with its own scheme for creating license plates.

Can't test it right now, but if you look for a Swiss, Belgian and French (old and new) license plate you'll see they have nothing in common.

That's just ... weird. I wonder how the developers, who reasonably have spent quite a while looking at and thinking about license plates, can make such an error.

It would of course have helped if they had provided more documentation regarding what the software considers to be the differences between US and European plates that makes it able to cope with all of Europe as a single mode, but not with US' plates.

From what they write in their live demo[1], it's about the dimensions of the plate rather than what's on them:

> OpenALPR supports both North American style (12 inches by 6 inches) and European style (52 cm by 11 cm) license plates.

That makes a bit more sense. Then again, the "Country" field there gives a choice of North American, European, Australia, Great Britain, Singapore, Korea.

I wonder if accuracy couldn't be improved quite a bit if they included heuristics for individual countries. For instance, German licence plates should be really easy to read thanks to their "forgery-impeding typeface"[2] which has uniquely distinctive features for each letter.

It's also not guaranteed that all European licence plates have those dimensions. Motorcycles and tractors for instance have taller, narrower plates, and cars where regular plates wouldn't fit (like imported or antique cars) can get special plates as well.

And then of course there's Switzerland which has wildly different dimensions and has changed its mind every few years[3].

[1] http://www.openalpr.com/demo-image.html

[2] https://en.wikipedia.org/wiki/FE-Schrift

[3] https://en.wikipedia.org/wiki/Vehicle_registration_plates_of...

"The common EU format of having a blue section on the extreme left with EU circle of stars and the country code was introduced by Council Regulation (EC) No 2411/98 of 3 November 1998[1] and entered into force on the 11 November 1998."

https://en.wikipedia.org/wiki/Vehicle_registration_plates_of...

Maybe not all countries adopt the EU standard, but it makes sense that there is an "eu" mode.

Here in the UK it is fairly common for vehicle plates not to have the blue EU section. The window next to me overlooks an office carpark, and of the twelve vehicles with visible plates only three have the EU section. The rest are plain, unadorned plates.

Edit: UK plates may also have a "national emblem" [1] instead of the EU logo.

[1] https://en.wikipedia.org/wiki/Vehicle_registration_plates_of...

Yes, that are common plates. But there are also special ones. Look at the personalized plates in austria.https://en.wikipedia.org/wiki/Vehicle_registration_plates_of...

As an Australian living in Japan all of those plates look remarkably similar. It wouldn't surprise me if all of them were covered under the 'eu' directive.

Of course, my point was simply that there IS an EU rule, and therefore it makes sense to simply have an 'eu' mode that acts upon the rule even if it doesn't cover all EU plates.

My experience with other (commercial) NPR is, that it's better to narrow down your expected search results to those countries you are looking for. The whole EU would be too wide...

There is a slight issue with this library in that it is "gimped" to one CPU. You can licence a multi-cpu version http://www.openalpr.com/ but the open source one would be a lot cooler.

The license says its AGPLv3. Is there an additional restriction somewhere that prevents one from modifying the code to run on multiple CPUs?

No GPL version allows adding such restrictions.

What is the best way to integrate this with a camera?

Is there any specific IPTV cam platform?

Most cameras offer a HTTP interface to acquire images. You can feed those to the LPR. Some LPR stacks offer recognition of license plates directly from video streams (MJPG, H.264).

It missed a G on my test image.

A very interesting project nonetheless.

How does this work internally. Its not using a neural net is it?

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