License Plate Recognition and Perform OCR from video

[Husnain]

I have to do License Plate Recognition and Perform OCR during video streaming... Please can anybody help me...

[jannoxi]

Hello,
I am new at AForge but do some work with Pattern recognition.
if i need to solve it i would splitt up the Problem by
1. get the Picture of the Plate: for extract "Crob" an Image from the Plate i thing is hart to find. Plates got different Colors and can be placed everyware But most plades got an white Background so
FiltersSequence seq = new FiltersSequence();
seq.Add(Grayscale.CommonAlgorithms.Y);
seq.Add(new Threshold(???)); // maybe 210 ?

And than searching for an Blob of an Plate size. In Germany is quit simple because Plates got allmost the same size, US or Italy it's quit harder.
// create an instance of blob counter algorithm
BlobCounterBase bc = new BlobCounter( );
// set filtering options
bc.FilterBlobs = true;
bc.MinWidth = 5; // Plate min Width
bc.MinHeight = 5; // Plate min Height
//Shure there is also an Plate max Width and Height .........
// set ordering options
bc.ObjectsOrder = ObjectsOrder.Size;
// process binary image
bc.ProcessImage( image );
Blob[] blobs = bc.GetObjectsInformation( );
// extract the biggest blob
if ( blobs.Length > 0 )
{
bc.ExtractBlobsImage( image, blobs[0], true );
}

Now we got in best case just on Blob, now you need to go for Letter, hier is using Pattern a good idea.
ExhaustiveTemplateMatching tm = new ExhaustiveTemplateMatching(0);
TemplateMatch[] matchings = tm.ProcessImage(PlateImage, LetterPattern); // Important , both PlateImage AND LetterPattern must be with allmost the same Threshold
//It's important to restrict the Areas of the PlateImage to get the Lettern in the correct Sequence
//All Patterns shoult be compared and the best Match is the Hit, to get faster you can stop after an Match of 95% !?

This is my first idea, I know an Example of OpenVisionControl there is exactly this Szenario, maybe go for it an have an look of the algorithm to rebuild with AForge.

By Markus