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：
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;