Different results of code language conversion [closed]

asked 2018-02-15 18:14:05 -0500

Murilo Pereira gravatar image

Hello everyone, I'm developing an OMR Application in Java/Android, I get a sample to this but that was in C++, so I started to convert the code to Java, when I finish it, the result was completely different that was apresented at the sample and I don't know why.

Expected result:

image description

The received result:

image description

The C++ code:

    #include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <iostream>
#include <vector>
#include <algorithm>

//g++ main.cpp -o main -I /usr/local/include/opencv -lopencv_core -lopencv_imgproc -lopencv_highgui

using namespace cv;
using namespace std;

cv::Point2f computeIntersect(cv::Vec4i a, cv::Vec4i b)
    int x1 = a[0], y1 = a[1], x2 = a[2], y2 = a[3];
    int x3 = b[0], y3 = b[1], x4 = b[2], y4 = b[3];

    if (float d = ((float)(x1-x2) * (y3-y4)) - ((y1-y2) * (x3-x4)))
        cv::Point2f pt;
        pt.x = ((x1*y2 - y1*x2) * (x3-x4) - (x1-x2) * (x3*y4 - y3*x4)) / d;
        pt.y = ((x1*y2 - y1*x2) * (y3-y4) - (y1-y2) * (x3*y4 - y3*x4)) / d;
        return pt;
        return cv::Point2f(-1, -1);

bool comparator2(double a,double b){  
  return a<b;  
 bool comparator3(Vec3f a,Vec3f b){  
  return a[0]<b[0];  

bool comparator(Point2f a,Point2f b){  
  return a.x<b.x;  
 void sortCorners(std::vector<cv::Point2f>& corners, cv::Point2f center)  

   std::vector<cv::Point2f> top, bot;  
   for (int i = 0; i < corners.size(); i++)  
     if (corners[i].y < center.y)  


   cv::Point2f tl = top[0];  
   cv::Point2f tr = top[top.size()-1];  
   cv::Point2f bl = bot[0];  
   cv::Point2f br = bot[bot.size()-1]; 

int main(int argc, char* argv[]){

  Mat img = imread("example.jpg",0);

  cv::Size size(3,3);  
  adaptiveThreshold(img, img,255,CV_ADAPTIVE_THRESH_MEAN_C, CV_THRESH_BINARY,75,10);  
  cv::bitwise_not(img, img);    

  cv::Mat img2;  
  cvtColor(img,img2, CV_GRAY2RGB);  

  cv::Mat img3;  
  cvtColor(img,img3, CV_GRAY2RGB); 

  vector<Vec4i> lines;  
  HoughLinesP(img, lines, 1, CV_PI/180, 80, 400, 10);  
  for( size_t i = 0; i < lines.size(); i++ )  
   Vec4i l = lines[i];  
   line( img2, Point(l[0], l[1]), Point(l[2], l[3]), Scalar(0,0,255), 3, CV_AA);   


  std::vector<cv::Point2f> corners;
  for (int i = 0; i < lines.size(); i++)
      for (int j = i+1; j < lines.size(); j++)
          cv::Point2f pt = computeIntersect(lines[i], lines[j]);
          if (pt.x >= 0 && pt.y >= 0 && pt.x < img.cols && pt.y < img.rows)

   // Get mass center  
  cv::Point2f center(0,0);  
  for (int i = 0; i < corners.size(); i++)  
  center += corners[i];  
  center *= (1. / corners.size()); 

  sortCorners(corners, center); 

  Rect r = boundingRect(corners); 
  cv::Mat quad = cv::Mat::zeros(r.height, r.width, CV_8UC3);  
  // Corners of the destination image  
  std::vector<cv::Point2f> quad_pts;  
  quad_pts.push_back(cv::Point2f(0 ...
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Closed for the following reason question is not relevant or outdated by sturkmen
close date 2020-10-27 09:22:46.956267



Can you at least try to narrow the problem down by yourself? Without that, you pretty much are asking us to debug both pieces of code. How about you run both versions and compare the results either line by line or function by function. This way you are able to pinpoint the exact problem. Should you fail to resolve it, come back with a clearer question.

eshirima gravatar imageeshirima ( 2018-02-15 18:48:13 -0500 )edit