Hough Lines. Find license plates

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topRenu
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Joined: 2018-06-06T12:48:57-07:00
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Hough Lines. Find license plates

Post by topRenu » 2018-06-06T13:41:05-07:00

Good day, community. I am trying to make ANPR. Recognition of Russian license plates. I am trying to follow these steps:
1. I make this first(contrast, threshold, canny and hough-lines then).
'convert /srv/http/r/1.jpg \\( +clone -contrast-stretch 10%x10% -despeckle -threshold 50% -despeckle -canny 0x1+10%+30% -write 2.jpg \-background none -fill red -stroke blue -strokewidth 1 \-hough-lines 50x50+100 -write lines.mvg \) -composite final.jpg
2. Find corners of intersected lines and cut the license plate
3. Make 3Drotate(by Fred's script)
4. Try to OCR image.
Also I found this document about ANPR, and i tried to follow this: http://www.iaeng.org/publication/WCECS2 ... 99-203.pdf

My problem is at first step, when i execute the command(canny -> hough-lines) i got a lot of lines in mvg file and sometime it is not giving me needed rectangle(only 1 or 2 of 4 needed sides), and some images it can even detect needed lines. So seems i need help in better adjustment of canny and hough-lines, but i dont know how to. Thank you for your help.
Some image examples:
FIRST EXAMPLE:
Image
Image
Image

SECOND EXAMPLE:
Image
Image
Image

THIRD EXAMPLE:
Image
Image
Image

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