opencv 3.0 Mat 初始化 eye ones zeros create randn

Mat在opencv中起到很重要的作用，是数据的容器

1. 首先是 eye, ones, zeros

    Mat eye   = Mat::eye(4,4,CV_8U);
    Mat ones  = Mat::ones(4,4,CV_8U);
    Mat zeros = Mat::zeros(4,4,CV_8U);

2. 直接初始化Mat的元素，小矩阵很方便

    Mat img = (Mat_<double>(3,3) << 1, 2, 3, 4, 5, 6, 7, 8, 9);

3. create分配内存，不初始化元素

    Mat m;
    m.create(4, 4, CV_8U);
    cout << m << endl;

4. 随机数矩阵 randn

    Mat r = Mat(3,3,CV_8UC3);
    randu(r, Scalar::all(0), Scalar::all(255));
    cout << r << endl;