[Chicago] OpenALPR - Transformations

Jordan Bettis jordanb at hafd.org
Fri Nov 4 13:52:44 EDT 2016

I've not used OpenALPR but mathematically what you need is projective

Presumably you should be able to obtain reference shape like that of the
license plate itself.

It will be a quadrilateral that won't be a rectangle unless your line of
sight is perpendicular to the plate's plane. Your job is determine the
geometric transformations you need to turn it into a rectangle. Then,
apply the same transformations to the contents of the image.

Here's an example of transforming an irregular quadrilateral into a
rectangle using scikit-image:


On 11/03/2016 02:52 PM, Chris Vinzons wrote:
> Hi,
> I'm using OpenALPR to read still license plates, but the thing is that
> my sometimes that it doesn't read it correctly. I think this is because
> of the license plate is tilted. Is there a way to untilt it or is there
> some kind of training data I could do in python?
> Thanks
> Chris V
> _______________________________________________
> Chicago mailing list
> Chicago at python.org
> https://mail.python.org/mailman/listinfo/chicago

More information about the Chicago mailing list