Opencv Cpp Program to convert color image to grey scale

#include "opencv\cv.h"
#include "opencv\highgui.h"
#define fname "image/baboon.jpg"
int main(int argc, char** argv())
{

    char * file = fname;
    IplImage * img2 = cvLoadImage(file, CV_LOAD_IMAGE_GRAYSCALE);
    cvSaveImage("output/grey.jpg", img2);
    cvNamedWindow( "Grey", CV_WINDOW_AUTOSIZE );
    cvShowImage("Grey", img2);
    cvWaitKey(0);
    cvDestroyWindow("Grey");
    cvReleaseImage(&img2);
    return 0;
}