I just studied the Algorithm of ANPR (Automatic Number Plate Recognition) from the chp 5 of book Packtpub.Mastering.OpenCV.with.Practical.Computer.Vision.Projects in which they detect the vehicle licence plate , but their are some restriction in that algorithm , i call it restriction because its specific for one country and can not be used in my country , well in that algorithm they use the following algorithms to detect the licence plate area
Threshold operation (otsu)
Close Morphological operation
Mask of one filled area
But the thing they used is the background color of licence plate as their keypoint for the recognition and detection , but in my area licence plate have different backgrounds , most common are black , white and green , green is not much common but rarely used , black background used white number and white contain black numbers , they use floodfill algorithm for white background , but what should i use for 2 different backgrounds ? Size of the licence plate and size of character matter in any case ?
Here are the sample images of my regional vehicle's liecence plate