Question

Possible Duplicate:
OpenCV rgb value for cv::Point in cv::Mat

As you know, in matlab it’s easy to get r/g/b values using r = image(:,:,1).

But in openCV (before 2.2) we must use pointer like this:

plImage* img=cvCreateImage(cvSize(640,480),IPL_DEPTH_32F,3);
((float *)(img->imageData + i*img->widthStep))[j*img->nChannels + 0]=111; // B
((float *)(img->imageData + i*img->widthStep))[j*img->nChannels + 1]=112; // G
((float *)(img->imageData + i*img->widthStep))[j*img->nChannels + 2]=113; // R

But as openCV2.3 comes out, it’s easy to get pixel value of a single channel image like this:

Mat image;
int pixel = image.at<uchar>(row,col);

So I just wonder it there also a easy way to get the r,g,b pixel value of a multichannel image just like that in the Matlab? Any help will be appreciated =)

Answer 1

For C++ interface you can do:

Vec3f pixel = image.at<Vec3f>(row, col);

int b = pixel[0];
int g = pixel[1];
int r = pixel[2];