OpenCV读取图像时Alpha通道的处理

近日研究OpenCV的templateMatch，发现读取的template如果带有Alpha通道，那么templateMatch无法得到正确的结果，因此，尝试在遇到这种情况时，通过算法合并Alpha通道到BGR通道上，由于目标图像背景为纯黑，所以，这里没做其它的计算。
代码如下：

/* * ===  FUNCTION  ====================================================================== *         Name:  main *  Description: * ===================================================================================== */int main ( int argc, char *argv[] ){    Mat img =   imread( argv[1], -1 );    if( img.empty() ) return -1;    cout << "Image Depth:\t" << depth_string[ img.depth() ] << endl;    cout << "Image Channels:\t" << img.channels() << endl;    cout << "Image Dims:\t" << img.dims << endl;    cout << "Image Size:\t" << img.size() << endl;    cout << "Image Total:\t" << img.total() << endl;    cout << "Image is Submatrix:\t" << img.isSubmatrix() << endl;    cout << "Image Rows:\t" << img.rows << endl;    cout << "Image Columns:\t" << img.cols << endl;    cout << "Image is Continuous:\t" << ( img.isContinuous() ? "true" : "false" ) << endl;    if( img.channels() == 4 )                     /* Should be checked if it is BGRA format */    {        Mat _dst;        Mat _chs[4];        cout << "Image is BGRA format, convert it to BGR format." << endl;        split( img, _chs );        for( int i = 0; i < 4; i ++ )        {            multiply( _chs[i], _chs[3], _chs[i] );        }        merge( _chs, 3, _dst );        img =   _dst;    }    namedWindow( "Window", WINDOW_AUTOSIZE );    imshow( "Window", img );    waitKey( 0 );    destroyWindow( "Show Image" );    return 0;}               /* ----------  end of function main  ---------- */