Revision history [back]

If you are using IplImage * you need to use myIplImage->height, myIplImage->widht etc. You can use image data using below code

int width     = img->width;
int height    = img->height;
int nchannels = img->nChannels;
int step      = img->widthStep;

uchar *data = ( uchar* )img->imageData;    
for(int  i = 0 ; i < height ; i++ ) {
    for(int j = 0 ; j < width ; j++ ) {
        int r = data[i*step + j*nchannels + 0];
        int g = data[i*step + j*nchannels + 1];
        int b = data[i*step + j*nchannels + 2];   
    }
}

Or using another method

for(int i=pix; i<img->height; i++)
    {
      for(int j=0; j<img->width; j++)
       {
         CvScalar ele;
         ele=cvGet2D(img,i,j);
         int B= ele.val[0]; //Blue channel
         int G=ele.val[1]; //Green channel
         int R=ele.val[2]; //Red channel

       }
     }

And if you are using Mat, See OpenCV documentation and this discussion for more details.