Grabbing Pixel data from a video strem - opencv

Question

I am having trouble if understanding certain coding i am sorry if this comes off as stupid but i have a code to capture a video from my webcam i want to get the RGB valuee from the frame, if this is impossible would have to to save a frame as a picture and then get values from it?
const char window_name[]="Webcam";
int main(int argc, char* argv[])
{
/* attempt to capture from any connected device */
CvCapture *capture=cvCaptureFromCAM(CV_CAP_ANY);
if(!capture)
{
printf("Failed to initialise webcam\n");
return -1;
}
/* create the output window */
cvNamedWindow(window_name, CV_WINDOW_NORMAL);
do
{
/* attempt to grab a frame */
IplImage *frame=cvQueryFrame(capture);
if(!frame)
{
printf("Failed to get frame\n");
break;
}
COLORREF myColAbsolute = GetPixel(frame, 10,10);//error in saying frame is not compatible with HDC.
cout << "Red - " << (int)GetRValue(myColAbsolute) << endl;
cout << "Green - " << (int)GetGValue(myColAbsolute) << endl;
cout << "Blue - " << (int)GetBValue(myColAbsolute) << endl;
/* show the frame */
cvShowImage(window_name, frame);

Answer 1

ha ! ( obviously caught with a copy & paste bummer )
GetPixel() is a windows function, not an opencv one. same for GetRValue() and sisters.
you'd use them in the native win32 api, to get a pixel from an HDC, but it won't work with opencv/highgui, since neither HDC, nor HWND are exposed.
since you're obviously a beginner(nothing wrong with that, again!) let me try to talk you out of using the old, 1.0 opencv api(IplImages, cv*Functions) as well,
you should be using the new one(cv::Mat, namespace cv::Functions) instead.
#include "opencv2/opencv.hpp"
#include "opencv2/highgui/highgui.hpp"
using namespace cv;
using namespace std;
int main()
{
Mat frame;
namedWindow("video", 1);
VideoCapture cap(0);
while ( cap.isOpened() )
{
cap >> frame;
if(frame.empty()) break;
int x=3, y=5;
// Ladies and Gentlemen, the PIXEL!
Vec3b pixel = frame.at<Vec3b>(y,x); // row,col, not x,y!
cerr << "b:" << int(pixel[0]) << " g:" << int(pixel[1]) << " r:" << int(pixel[2]) << endl;
imshow("video", frame);
if(waitKey(30) >= 0) break;
}
return 0;
}