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enter image description hereI am developing a number plate recognition system and I have managed to locate the number plate area successfully. But I need to filter out the false number plate areas from the image. I am thinking is to use a histogram and probably check the horizontal pixel intensity.

would this be a correct approach? or are there any better approach?

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You may need to be more specific because number plates in different countries (or states, or counties) can look different. As well as government issue plates, fleet plates, front vs rear plates, personalized plates and the year of the plate can all have different color schemes. Is white the lettering or the background, what's the contrasting color? –  joocer Jul 13 '12 at 11:18
@joccer I am targeting the UK number plates with white lettering and black background. –  Mr.Noob Jul 13 '12 at 11:34
Might be helpful if you put an image of a UK plate up here so we can see what you are referencing! –  trumpetlicks Jul 13 '12 at 14:06
@trumpetlicks ive attached the image! thanks –  Mr.Noob Jul 14 '12 at 17:14
OK, so what do you mean by the "false number plate area"? –  trumpetlicks Jul 14 '12 at 17:38

2 Answers 2

The plate is an aerea of high contrast, you should take advantage of that. Also there are a lot of edges, and especially 90 degrees edges.

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yeah you are right! Can I use something like a histogram to get the maximum vertical edge intensity? Does it make sense? or is it even possible? I'm sorry I'm quite blunt on this –  Mr.Noob Jul 14 '12 at 21:41
edge detection is a matter no-one could explain in a few words, i'm afraid. Contrast is more simple, first have a try with your bank of test input image to see how well it works with contrast. –  GameAlchemist Jul 15 '12 at 9:31

Take a look at this example using EmguCV in C#, maybe you can find something useful, it is example of recognizing a stop sign: Stop sign detection

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