Part 1: Extracting contours from text

/*
ayoungprogrammer.blogspot.com

Part 1: Extracting contours from text

*/

#include <iostream>

 #include <Windows.h>

#ifdef _CH_
#pragma package <opencv>
#endif

#ifndef _EiC
#include "cv.h"
#include "highgui.h"
#include "ml.h"
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#endif

using namespace std;
using namespace cv;


class comparator{
public:
    bool operator()(vector<Point> c1,vector<Point>c2){

        return boundingRect( Mat(c1)).x<boundingRect( Mat(c2)).x;

    }

};



void extractContours(Mat& image,vector< vector<Point> > contours_poly){



    //Sort contorus by x value going from left to right
    sort(contours_poly.begin(),contours_poly.end(),comparator());


    //Loop through all contours to extract
     for( int i = 0; i< contours_poly.size(); i++ ){

        Rect r = boundingRect( Mat(contours_poly[i]) );


        Mat mask = Mat::zeros(image.size(), CV_8UC1);
        //Draw mask onto image
        drawContours(mask, contours_poly, i, Scalar(255), CV_FILLED);

        //Check for equal sign (2 dashes on top of each other) and merge
        if(i+1<contours_poly.size()){
            Rect r2 = boundingRect( Mat(contours_poly[i+1]) );
            if(abs(r2.x-r.x)<20){
                //Draw mask onto image
                drawContours(mask, contours_poly, i+1, Scalar(255), CV_FILLED);
                i++;
                int minX = min(r.x,r2.x);
                int minY = min(r.y,r2.y);
                int maxX =  max(r.x+r.width,r2.x+r2.width);
                int maxY = max(r.y+r.height,r2.y+r2.height);
                r = Rect(minX,minY,maxX - minX,maxY-minY);

            }
        }
        //Copy
         Mat extractPic;
         //Extract the character using the mask
         image.copyTo(extractPic,mask);
         Mat resizedPic = extractPic(r);

        cv::Mat image=resizedPic.clone();

        //Show image
        imshow("image",image);
        char ch  = waitKey(0);
        stringstream searchMask;
        searchMask<<i<<".jpg";
        imwrite(searchMask.str(),resizedPic);

     }





}

void getContours(const char* filename)
{
  cv::Mat img = cv::imread(filename, 0);


  //Apply blur to smooth edges and use adapative thresholding
   cv::Size size(3,3);
  cv::GaussianBlur(img,img,size,0);
   adaptiveThreshold(img, img,255,CV_ADAPTIVE_THRESH_MEAN_C, CV_THRESH_BINARY,75,10);
  cv::bitwise_not(img, img);




  cv::Mat img2 = img.clone();


  std::vector<cv::Point> points;
  cv::Mat_<uchar>::iterator it = img.begin<uchar>();
  cv::Mat_<uchar>::iterator end = img.end<uchar>();
  for (; it != end; ++it)
    if (*it)
      points.push_back(it.pos());

  cv::RotatedRect box = cv::minAreaRect(cv::Mat(points));

   double angle = box.angle;
  if (angle < -45.)
    angle += 90.;

  cv::Point2f vertices[4];
  box.points(vertices);
  for(int i = 0; i < 4; ++i)
    cv::line(img, vertices[i], vertices[(i + 1) % 4], cv::Scalar(255, 0, 0), 1, CV_AA);



   cv::Mat rot_mat = cv::getRotationMatrix2D(box.center, angle, 1);

   cv::Mat rotated;
  cv::warpAffine(img2, rotated, rot_mat, img.size(), cv::INTER_CUBIC);



  cv::Size box_size = box.size;
  if (box.angle < -45.)
    std::swap(box_size.width, box_size.height);
  cv::Mat cropped;

  cv::getRectSubPix(rotated, box_size, box.center, cropped);
  cv::imshow("Cropped", cropped);
  imwrite("example5.jpg",cropped);

    Mat cropped2=cropped.clone();
cvtColor(cropped2,cropped2,CV_GRAY2RGB);

Mat cropped3 = cropped.clone();
cvtColor(cropped3,cropped3,CV_GRAY2RGB);

 vector<vector<Point> > contours;
  vector<Vec4i> hierarchy;

  /// Find contours
  cv:: findContours( cropped, contours, hierarchy, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_TC89_KCOS, Point(0, 0) );



  /// Approximate contours to polygons + get bounding rects and circles
  vector<vector<Point> > contours_poly( contours.size() );
  vector<Rect> boundRect( contours.size() );
  vector<Point2f>center( contours.size() );
  vector<float>radius( contours.size() );


  //Get poly contours
    for( int i = 0; i < contours.size(); i++ )
     {
         approxPolyDP( Mat(contours[i]), contours_poly[i], 3, true );
     }


  //Get only important contours, merge contours that are within another
  vector<vector<Point> > validContours;
    for (int i=0;i<contours_poly.size();i++){

        Rect r = boundingRect(Mat(contours_poly[i]));
        if(r.area()<100)continue;
        bool inside = false;
        for(int j=0;j<contours_poly.size();j++){
            if(j==i)continue;

            Rect r2 = boundingRect(Mat(contours_poly[j]));
            if(r2.area()<100||r2.area()<r.area())continue;
            if(r.x>r2.x&&r.x+r.width<r2.x+r2.width&&
                r.y>r2.y&&r.y+r.height<r2.y+r2.height){

                inside = true;
            }
        }
        if(inside)continue;
        validContours.push_back(contours_poly[i]);
    }


    //Get bounding rects
    for(int i=0;i<validContours.size();i++){
        boundRect[i] = boundingRect( Mat(validContours[i]) );
    }


    //Display
  Scalar color = Scalar(0,255,0);
  for( int i = 0; i< validContours.size(); i++ )
     {
    if(boundRect[i].area()<100)continue;
      drawContours( cropped2, validContours, i, color, 1, 8, vector<Vec4i>(), 0, Point() );
       rectangle( cropped2, boundRect[i].tl(), boundRect[i].br(),color, 2, 8, 0 );
     }

  //imwrite("example6.jpg",cropped2);
  imshow("Contours",cropped2);

  extractContours(cropped3,validContours);

cv::waitKey(0);

}





int main(void){

char fileName[256];
cin>>fileName;
getContours(fileName);

}