Pixcel values in 2 different frames always show to be the same.

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I capture 2 different frames yet when I try to compare pixcel values between the 2 frames, they appear to be identical. I am probable misusing Vec3b. Please help an obvious novice. Thanks.

// November 11 2013 Capture and display values of 2 full color frames
#include "stdafx.h"
#include "iostream"
#include "opencv2/core/types_c.h"
#include "opencv2/opencv.hpp"
using namespace cv;
int main(int, char**)
{
    VideoCapture cap(0); // open the default camera
    if(!cap.isOpened())  // check if we succeeded
        return -1;   

    namedWindow("frame",1);
    for(;;)
    {
        Mat frame;
        cap >> frame; // get frame from camera

        imshow("frame", frame);

        if(waitKey(1000) >= 0) break;

        Mat frame1;
        cap >> frame1; // get frame1 from camera    

        imshow("frame1", frame1);

        if(waitKey(1000) >= 0) break;


        for(int i=0; i<480; i++)
            for(int j=0; j<640; j++)
                {cv::Vec3b tmp1 = frame1.at<cv::Vec3b>(i,j);std::cout << "i= "<<i<<" j= "<<j<< " frame1  "<<(int)tmp1(0) << " " << (int)tmp1(1) << " " << (int)tmp1(2)<< std::endl;
                 cv::Vec3b tmp = frame.at<cv::Vec3b>(i,j);std::cout << "          frame   "<<(int)tmp(0) << " " << (int)tmp(1) << " " << (int)tmp(2)<< std::endl;

        if(waitKey(1000) >= 0) break;
        }

        if(waitKey(1000) >= 0) break;
    }
    // the camera will be deinitialized automatically in VideoCapture destructor
    return 0;
}