Using Mat::at(i,j) in opencv for a 2-D Mat object

Question

I am using Ubuntu 12.04 and OpenCV 2

I have written the following code :

IplImage* img =0;
img = cvLoadImage(\"nature.jpg\");
if(img != 0)
{
    Mat         


        

Answer 1

You have to specify the correct type for cv::Mat::at(i,j). You are accessing the pixel as int, while it should be a vector of uchar. Your code should look something like this:

IplImage* img = 0;
img = cvLoadImage("nature.jpg");
if(img != 0)
{
  Mat Img_mat(img);
  std::vector BGR;
  split(Img_mat, BGR);

  Vec3b data = BGR[0].at(i,j);
  // data[0] -> blue
  // data[1] -> green
  // data[2] -> red
}