[OpenCV/cpp] Mat의 at함수

출처 : https://docs.opencv.org/trunk/d3/d63/classcv_1_1Mat.html

_Tp& cv::Mat::at(int i0 = 0)

Returns a reference to the specified array element.

The template methods return a reference to the specified array element. For the sake of higher performance, the index range checks are only performed in the Debug configuration.

Note that the variants with a single index (i) can be used to access elements of single-row or single-column 2-dimensional arrays. That is, if, for example, A is a 1 x N floating-point matrix and B is an M x 1 integer matrix, you can simply write A.at<float>(k+4) and B.at<int>(2*i+1) instead of A.at<float>(0,k+4)and B.at<int>(2*i+1,0), respectively.

• If matrix is of type CV_8U then use Mat.at<uchar>(y,x).
• If matrix is of type CV_8S then use Mat.at<schar>(y,x).
• If matrix is of type CV_16U then use Mat.at<ushort>(y,x).
• If matrix is of type CV_16S then use Mat.at<short>(y,x).
• If matrix is of type CV_32S then use Mat.at<int>(y,x).
• If matrix is of type CV_32F then use Mat.at<float>(y,x).
• If matrix is of type CV_64F then use Mat.at<double>(y,x).