Question

I’m new to the c++ interface and running out of ideas about this code:

//buffer : VideoCapture >> cvtColor >> Canny

for(int i=0;i<buffer.rows;i++) //search for edges
{
    for (int j=0 ;j<buffer.cols;j++)
    {
        Vec3b pixel=buffer.at<Vec3b>(i,j);
    }
}

runs fine in debug mode but crashing at some point (i=479, j=448) in release.(oh and can’t catch any exception… of course…)

but

Vec3b pixel=buffer.at<Vec3b>(1,1000);

works in elease even if my image(buffer) is 640*480.

I think i am missing something. I’d be thankfull to you guys if you can get some sense out of this.

Answer 1

You are using a Vec3b iterator which is supposed to be used on 3 channel images. You are using a single channel image, to iterate such an image you have to replace Vec3b with uchar.