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c#imageimage-processingcolorsautomatic-license-plate-recognition

License Plate Recognition - Determining Color Range For Pixel Comparison


Well after much work regarding vehicle plate detection, I've decided that simply finding a 'pattern' of yellow pixels within an image would be a sufficient method of finding the location of a license plate within an image. Currently I use various graphic filters and detect white pixel patterns, however this is proving to be more and more problematic.

Now for the question, I'm aware that the 'yellow' are a license plate is based on numerous factors such as brightness, environment. alt text alt text

Insight of this I would need a range to compare to, for example:

if(FindIfYellow(GetPixel(x, y)))

However I don't know if to use RGB values, specifically individual RGB values to determine if the color is a shade of yellow. Finally is there a website or information of some sort defining these ranges? I know

R: 255 G: 255 B: 0

Is the purest of yellow, but in terms of range I have no idea. Anyway hopefully it's a resonable idea, and the reason I post is to ensure I haven't overlook something, as I have been doing frequently :).


Solution

  • Using CMYK channel separation - Let's OCR the Plate!

    enter image description here

    Repeating the process with the other image

    enter image description here