java - OpenCV + Android + Vehicle number Plate Recognition -

i'm developing android app detect vehicle number plate. did image processing findcontours level of image. need convert following c++ code opencv based android java.

this original image

this after otsu thresholding image

this andoid+opencv code (working 100%)

imageview imgview  = (imageview) findviewbyid(r.id.imageview1); bitmap bmp = bitmapfactory.decoderesource(getresources(),car); //first convert bitmap mat mat imagematin = new mat ( bmp.getheight(), bmp.getwidth(), cvtype.cv_8u, new scalar(4));     mat imagematout = new mat ( bmp.getheight(), bmp.getwidth(), cvtype.cv_8u, new scalar(4)); mat imagematbk = new mat ( bmp.getheight(), bmp.getwidth(), cvtype.cv_8u, new scalar(4)); mat imagemattophat = new mat ( bmp.getheight(), bmp.getwidth(), cvtype.cv_8u, new scalar(4)); mat temp = new mat ( bmp.getheight(), bmp.getwidth(), cvtype.cv_8u, new scalar(4));  bitmap mybitmap32 = bmp.copy(bitmap.config.argb_8888, true); utils.bitmaptomat(mybitmap32, imagematin);     //converting rgb gray. imgproc.cvtcolor(imagematin, imagematbk, imgproc.color_rgb2gray,8);      imgproc.dilate(imagematbk, temp, imgproc.getstructuringelement(imgproc.morph_rect, new size(9, 9))); imgproc.erode(temp, imagemattophat, imgproc.getstructuringelement(imgproc.morph_rect, new size(9,9)));    //core.absdiff(current, previous, difference); core.absdiff(imagemattophat, imagematbk, imagematout);        //sobel operator in horizontal direction.     imgproc.sobel(imagematout,imagematout,cvtype.cv_8u,1,0,3,1,0.4,imgproc.border_default);  //converting gaussianblur                    imgproc.gaussianblur(imagematout, imagematout, new size(5,5),2);      imgproc.dilate(imagematout, imagematout, imgproc.getstructuringelement(imgproc.morph_rect, new size(3,3)));  mat element = imgproc.getstructuringelement(imgproc.morph_rect, new size(17, 3));     imgproc.morphologyex(imagematout, imagematout, imgproc.morph_close, element);  //threshold image imgproc.threshold(imagematout, imagematout, 0, 255, imgproc.thresh_otsu+imgproc.thresh_binary); 

now need extract number plate

please me convert following c++ code java+opencv:.

std::vector rects;   std::vector<std::vector >::iterator itc = contours.begin();   while (itc != contours.end())   {       cv::rotatedrect mr = cv::minarearect(cv::mat(*itc));      float area = fabs(cv::contourarea(*itc));       float bbarea=mr.size.width * mr.size.height;       float ratio = area/bbarea;       if( (ratio < 0.45) || (bbarea < 400) ){           itc= contours.erase(itc);       }else{           ++itc;           rects.push_back(mr);       }   }  

looking @ http://docs.opencv.org/java , the documentation findcontours in particular

instead of

std::vector<std::vector<cv::point> > contours; 

you have

java.util.arraylist<matofpoint> contours; 

you can use contours.listiterator() traverse list. below (not compiled let alone run,likely contain major blunders):

import java.util.*; import org.opencv.imgproc.imgproc; import org.opencv.core.*;  /* ... */ arraylist<rotatedrect> rects = new  arraylist<rotatedrect>() arraylist<matofpoint> contours = new arraylist<matofpoint>(); imgproc.findcontours(image, contours, new mat(), imgproc.retr_external, imgproc.chain_approx_none);  listiterator<matofpoint> itc = contours.listiterator(); while(itc.hasnext()) {      matofpoint2f mp2f = new matofpoint2f(itc.next().toarray());      rotatedrect mr = imgproc.minarearect(mp2f);      double area = math.abs(imgproc.contourarea(mp2f));       double bbarea= mr.size.area();        double ratio = area / bbarea;        if( (ratio < 0.45) || (bbarea < 400) )      {            itc.remove();  // other deliberately making program slow,                         // erasing contour have purpose?      }      else      {            rects.add(mr);        }    }