Transform img to 1/2

IplImage* doPyrDown(  IplImage* in){    // Best to make sure input image is divisible by two.    //    assert( in->width%2 == 0 && in->height%2 == 0 );    IplImage* out = cvCreateImage(         cvSize( in->width/2, in->height/2 ),        in->depth,        in->nChannels    );    cvPyrDown( in, out );    return( out );};int _tmain(int argc, _TCHAR* argv[]){  IplImage* img = cvLoadImage("lena.jpg");  IplImage* img2;  cvNamedWindow("Example1", CV_WINDOW_AUTOSIZE );  cvNamedWindow("Example2", CV_WINDOW_AUTOSIZE );  cvShowImage("Example1", img );  img2 = doPyrDown( img );  cvShowImage("Example2", img2 );  cvWaitKey(0);  cvReleaseImage( &img );  cvReleaseImage( &img2 );  cvDestroyWindow("Example1");  cvDestroyWindow("Example2");}