character extraction from vehicle plate

I have used the matlab code given in the link https://www.mathworks.com/matlabcentral/fileexchange/44088-car-license-plate-reader?focused=3853315&tab=function for vehicle plate number recognition. I have to modify this code to suit for my plate but I haven't understood character extraction coding part given in myextractor.m. Can anyone please refer the code given in the link and help me. I am attaching kind of vehicle plate example.