Opencv cv::Mat利用at求像素点值

利用at取值时，一定要注意cv::Mat的类型

CV_8U(uchar)  
CV_8UC1 (uchar)  CV_8UC2 (Vec2b)  CV_8UC3 (Vec3b)  CV_8UC4(Vec4b) 

CV_8S(char)   
CV_8SC1 (uchar)  CV_8SC2 (Vec2b)   CV_8SC3 (Vec3b)  CV_8SC4 (Vec4b)   

CV_16U  (ushort)
CV_16UC1 (ushort)  CV_16UC2 (Vec2w)   CV_16UC3 (Vec3w)   CV_16UC4 (Vec4w)   

CV_16S  (short)
CV_16SC1(short)   CV_16SC2(Vec2s)   CV_16SC3(Vec3s)   CV_16SC4(Vec4s)   

CV_32S (int)
CV_32SC1(int)   CV_32SC2(Vec2i)    CV_32SC3(Vec3i)  CV_32SC4(Vec4i)   

CV_32F (float)
CV_32FC1(float)   CV_32FC2(Vec2f)  CV_32FC3(Vec3f)   CV_32FC4(Vec4f)  

CV_64F(double)  
CV_64FC1(double)   CV_64FC2(Vec2d)  CV_64FC3(Vec3d)  CV_64FC4(Vec4d) 

• 求出Mat的类型，返回值是一个int型的id，对应官方文档可以得出矩阵的类型

cv::Mat m_matrix;
std::cout< 
遍历像素点，需要注意参数第一个是行，第二个是列
 
std::cout<(row, col)<