opencv依据图像类型读取图像像素点

Mat数据类型和通道对应的type()：
库类型	C1	C2	C3	C4
CV_8U	0	8	16	24
CV_8S	1	9	17	25
CV_16U	2	10	18	26
CV_16S	3	11	19	27
CV_32S	4	12	20	28
CV_32F	5	13	21	29
CV_64F	6	14	22	30
通过c++程序查看类型并读取图像像素点：
cpp 复制代码
switch (im->type())
		{
		case 0:
			std::cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->at<uchar>(cv::Point(x, y))) << std::endl; break;
		case 1:
			std::cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->at<char>(cv::Point(x, y))) << std::endl; break;
		case 2:
			std::cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->at<ushort>(cv::Point(x, y))) << std::endl; break;
		case 3:
			std::cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->at<short>(cv::Point(x, y))) << std::endl; break;
		case 4:
			std::cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->at<int>(cv::Point(x, y))) << std::endl; break;
		case 5:
			std::cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->at<float>(cv::Point(x, y))) << std::endl; break;
		case 6:
			std::cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->at<double>(cv::Point(x, y))) << std::endl; break;
		case 16:
			std::cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->ptr<uchar>(y)[x * 3]) << "," << static_cast<int>(im->ptr<uchar>(y)[x * 3 + 1]) << "," << static_cast<int>(im->ptr<uchar>(y)[x * 3 + 2]) << std::endl; break;
		case 17:
			std::cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->ptr<char>(y)[x * 3]) << "," << static_cast<int>(im->ptr<char>(y)[x * 3 + 1]) << "," << static_cast<int>(im->ptr<char>(y)[x * 3 + 2]) << std::endl; break;
		case 18:
			std::cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->ptr<ushort>(y)[x * 3]) << "," << static_cast<int>(im->ptr<ushort>(y)[x * 3 + 1]) << "," << static_cast<int>(im->ptr<ushort>(y)[x * 3 + 2]) << std::endl; break;
		case 19:
			std::cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->ptr<short>(y)[x * 3]) << "," << static_cast<int>(im->ptr<short>(y)[x * 3 + 1]) << "," << static_cast<int>(im->ptr<short>(y)[x * 3 + 2]) << std::endl; break;
		case 20:
			std::cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->ptr<int>(y)[x * 3]) << "," << static_cast<int>(im->ptr<int>(y)[x * 3 + 1]) << "," << static_cast<int>(im->ptr<int>(y)[x * 3 + 2]) << std::endl; break;
		case 21:
			std::cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->ptr<float>(y)[x * 3]) << "," << static_cast<int>(im->ptr<float>(y)[x * 3 + 1]) << "," << static_cast<int>(im->ptr<float>(y)[x * 3 + 2]) << std::endl; break;
		case 22:
			std::cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->ptr<double>(y)[x * 3]) << "," << static_cast<int>(im->ptr<double>(y)[x * 3 + 1]) << "," << static_cast<int>(im->ptr<double>(y)[x * 3 + 2]) << std::endl; break;
		}
		break;