Hello to all!!! I'm doing a little project for rebuild une image. I must load image from my path then. I used a grid 40x40 pixels for divide image in some little images. I must then rebuild image in order adding a red background. I think that this project is a bit useless but this is for another project. For my project is very important the division of the image and its orderly reconstruction. I post below my solution:

#include <iostream>
#include <stdio.h>
#include <math.h>

#include <opencv2\opencv.hpp>
#include "opencv\highgui.h"
#include "opencv\cv.h"

using namespace cv;
using namespace std;

Mat add_piece_of_frame(Mat, Mat, int, int);
Mat add_piece_of_frame_red(Mat, Mat, int, int);

int main(int argc, char** argv)
{
    Mat bkg_read = imread("C:\\Users\\Fabrizio\\Desktop\\frame\\VIDEO_PER_TESI\\Scene1.jpg",CV_LOAD_IMAGE_COLOR);
    IplImage * bkg = cvCloneImage( &(IplImage)bkg_read );
    namedWindow("original", 1);
    cvShowImage("original", bkg);
    cvWaitKey(3333);

    //Mat background(bkg_read);


    Mat ricostruzione[48];
    int aa[48];
    int bb[48];
    int m = 0;

    for(int a=0; a<320; a+=40)
    {
        for(int b=0; b<240; b+=40)
        {
            Mat SUPPORT (bkg_read, Rect(a,b,40,40));
            ricostruzione[m] = SUPPORT.clone();
            aa[m] = a;
            bb[m] = b;
            cout<<"coordinate:  "<<endl;
            cout<<"a:  "<<aa[m];
            cout<<"   b:  "<<bb[m]<<endl;

            m++;
        }
    }

    int A=0;

    while(A<1)
    {
        Mat output = cv::Mat::zeros(240, 320, CV_32FC3);
        Mat output_red = cv::Mat::zeros(240, 320, CV_32FC3);


        for ( int t=0; t<48; t++)
        {
            output_red = add_piece_of_frame_red(ricostruzione[t] , output_red, aa[t] , bb[t]);
        }

        IplImage * exit_red = cvCloneImage( &(IplImage)output_red );
        namedWindow("output_red", 1);
        cvShowImage("output_red",exit_red);
        cvWaitKey(3333);



        for ( int u=0; u<48; u++)
        {
            output = add_piece_of_frame(ricostruzione[u] , output, aa[u] , bb[u]);
        }

        IplImage * exit = cvCloneImage( &(IplImage)output );
        namedWindow("output", 1);
        cvShowImage("output",exit);
        cvWaitKey(3333);

    }

}

Mat add_piece_of_frame(Mat A , Mat B, int r, int c)
{
    Rect Roi(r, c, 40, 40);
    B(Roi) = B(Roi) + A.clone();
    return B;
}

Mat add_piece_of_frame_red(Mat A, Mat B, int r, int c)
{
    Scalar color = Scalar(0, 0, 255);   
    Mat mask = Mat(40, 40, CV_32FC3, color);
    Mat result;
    addWeighted(A, 0.5, mask, 0.5, 0, result, CV_32FC3); 

    Rect Roi(r, c, 40, 40);             

    B(Roi) = B(Roi) + result.clone();

    return B;
}