How to calculate the average of multiple images

I am trying to get the average of multiple images with opencv, here is my code:

#include <opencv2\core\core.hpp>
#include <opencv2\highgui\highgui.hpp>
#include <opencv2\opencv.hpp>
using namespace std;
using namespace cv;

int main(){
    cv::Mat frame,frame32f;
    char filename[40];
    cv::Mat mean;
    const int count =10;
    const int width  = 1920;
    const int height = 1080;
    cv::Mat resultframe = cv::Mat::zeros(height,width,CV_32FC3);
    for(int i = 1 ; i<= count; i++){
        sprintf(filename,"d:\\BMdvideos\\images\\image%d.tiff",i);
        frame = imread(filename,CV_LOAD_IMAGE_COLOR);
        frame.convertTo(frame32f,CV_32FC3);
        resultframe +=frame32f;
        cout << " i = " << i<<endl;
        frame.release();
    }
    resultframe *= (1.0/count);

    imshow("",resultframe);
    waitKey(0);
    return 0;
}

      

        
        
        
      

    

I get always white frame in imshow, any idea why I am getting this. in advance for your help!