opencv write into a file the pixel values of binary image - c++

Question

I would like to ask question about on how to export/write all the pixel values into a txt file or other format that can be opened by notepad for example. Below the program.
Thanks, HB
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"
#include <stdio.h>
#include <stdlib.h>
#include<fstream>
using namespace cv;
using namespace std;
int main( int argc, char** argv )
{
IplImage *img = cvLoadImage("MyImg.png");
CvMat *mat = cvCreateMat(img->height,img->width,CV_32FC3 );
cvConvert( img, mat );
outFile.open("MyFile.txt");
for(int i=0;i<10;i++)
{
for(int j=0;j<10;j++)
{
/// Get the (i,j) pixel value
CvScalar scal = cvGet2D( mat,j,i);
printf( "(%.f,%.f,%.f)",scal.val[0], scal.val[1],scal.val[2] );
}
printf("\n");
}
waitKey(1);
return 0;
}

Answer 1

The class Mat of the new OpenCV C++ API is preferred over IplImage because it simplifies your code: read more about the class Mat. For more information about loading an image, you could read Load, Modify, and Save an Image.
In order to write a text file using C++, you could use the class ofstream
Here is the source code.
#include <opencv2/opencv.hpp>
using namespace cv;
#include <fstream>
using namespace std;
int main( int argc, char** argv )
{
Mat colorImage = imread("MyImg.png");
// First convert the image to grayscale.
Mat grayImage;
cvtColor(colorImage, grayImage, CV_RGB2GRAY);
// Then apply thresholding to make it binary.
Mat binaryImage(grayImage.size(), grayImage.type());
threshold(grayImage, binaryImage, 128, 255, CV_THRESH_BINARY);
// Open the file in write mode.
ofstream outputFile;
outputFile.open("MyFile.txt");
// Iterate through pixels.
for (int r = 0; r < binaryImage.rows; r++)
{
for (int c = 0; c < binaryImage.cols; c++)
{
int pixel = binaryImage.at<uchar>(r,c);
outputFile << pixel << '\t';
}
outputFile << endl;
}
// Close the file.
outputFile.close();
return 0;
}