Hong Kong (similar to United Kingdom) license plates are not recognized

[ghost]

Here are some Hong Kong (similar to United Kingdom / UK) license plates: https://www.dropbox.com/sh/b7ndg9tajbyr8mm/AAD-ab1eUAFLisx6TyFCVjIza?dl=0

I used http://www.openalpr.com/demo.html to upload images to have them recognized. The software does not return any results.

• How can one make OpenALPR work with Hong Kong license plates?
• Is it possible that a library can be added (i.e. via train-ocr)? If so, has anyone already written such an application?
• Does the UK license plate library already exist?

[vladimirr0708982]

Firs of all you have googlegroup for all question https://groups.google.com/forum/#!forum/openalpr

first you mast train detector ( you need minimum 3000 image of HK plates/cars ) after u tray you need yo make OCR lib base on you image/plates

and on the end you will have good reading

thanks Vladimir

[ghost]

Thank you for your quick reply and insight, much appreciated. I am willing to do this job. The images need to be in what format (bmp, png, jpeg, jpeg2k, raw)? Who will I email them to for creating this library (i.e. dropbox)?

Can you advise: Distance to number plate (m): Distance off the line of travel (m), i.e. angle: Height of camera (m), i.e. is 1 m:

[matthill]

You want to place the camera in realistic conditions. The image needs to be clear and easy to read. The angle shouldn't be more than 30 degrees horizontally. The plate image (after being cropped) should be at least 150 or so pixels wide.

If you upload your images to You can upload images to an anonymous FTP here: upload.openalpr.com I can add them to my To do list. It would probably be at least a few months before I have time to work on it.

[matthill]

By the way, I just ran a few of those plates through on my local machine. I noticed that the images are stretched by about 2x in the x direction. When using them as-is, the plates are way too wide and are disqualified. However, when I compensate for the stretching (by rescaling the image and leaving the height as-is) the plates are properly detected.

The font is still too different from the EU fonts, so the results are not great. That's good news though, training just the OCR and using the EU detector is much simpler than having to train a detector as well. You won't need nearly as many samples. Just a couple hundred should suffice. You can copy the EU detector and config settings.

[yucolabjames]

Seems like the OCR db cloned from the github repo has trouble with the HK license plate.

This is the command I tried

C:\james>alpr 35088793804_42a9788362.jpg -c gb
No license plates found.

But using the Cloud API, it works!

Photo credits to Jamie Llyod 2014.