02_mat

//mat constructor
int rows=400,cols=600;//rows,列数，cols,行数
cv::Size size(cols,rows); //

cv::Mat myMat(rows,cols,CV_8UC3,Scalar(0,0,255));//行列与size，point不同
CV::Mat myMat=cv::Mat(rows,cols,CV_8UC1)
cv::Mat myMat(size,CV_8UC1);

Mat map = Mat::zeros(800, 600, CV_8UC1);//ones/eye/zeros

Mat A,B;//create the header parts
A=imread("img.png"); //allocate matrix
Mat C(A);   //copy constructor
B=A;   //assignment operator    
//these three point to the same single data matrix,
//even with different headers

//deep copy, copy the matrix data
B=A.clone();
A.copyTo(B);
Mat RowClone = C.row(1).clone();

//slice
img_creata.rowRange(0, 4).colRange(0,3);

//method1
map.at<uchar>(row, col) = 1;
img.at<Vec3b>(i,j)[k];  
//method2
uchar *data=(uchar*)map.data;
int index=i*cols+j;i=0;//rows-1
data[index];
/*
if color : 
    data[index * 3 + 0] = 0；
    data[index * 3 + 1] = 0;
    data[index * 3 + 2] = 0;
 */

//method3
//ptr()  Returns a pointer to the specified matrix row
for ( int i=0; i<rows; i++ )
{
    uchar *data = image.ptr<uchar>( i );
    for ( int j=0; j<cols; j++ )
    {
        data[j] = 0;
        //*data++=0;
        /*
            if color one:
            data[j*3 + 0] = 0;
            data[j*3 + 1] = 0;
            data[j*3 + 2] = 0;
        */
    }
}

void cvtColor(InputArray src, OutputArray dst, int code, int dstCn=0 );

//usual
cvtColor(src, bwsrc, CV_RGB2GRAY);
// dst=0.299r+0.587g+0.114b

Mat Mat::clone();
void Mat::copyTo(OutputArray m);
copyTo(OutputArray m, InputArray mask);

template<typename _Tp, int n> class Vec : public Matx<_Tp, n, 1> {...};

typedef Vec<uchar, 2> Vec2b;
typedef Vec<uchar, 3> Vec3b;
typedef Vec<uchar, 4> Vec4b;

typedef Vec<short, 2> Vec2s;
typedef Vec<short, 3> Vec3s;
typedef Vec<short, 4> Vec4s;

typedef Vec<int, 2> Vec2i;
typedef Vec<int, 3> Vec3i;
typedef Vec<int, 4> Vec4i;

typedef Vec<float, 2> Vec2f;
typedef Vec<float, 3> Vec3f;
typedef Vec<float, 4> Vec4f;
typedef Vec<float, 6> Vec6f;

typedef Vec<double, 2> Vec2d;
typedef Vec<double, 3> Vec3d;

typedef Vec<double, 4> Vec4d;
typedef Vec<double, 6> Vec6d;