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OpenCV的中高效的像素遍歷方法，寫出工程級像素遍歷代碼 [ C++ OpenCV 依序取出像素值的各種寫法 – 越後面效率越高，但越看不懂 ] 資料來源:https://mp.weixin.qq.com/s/jfLdvLgAuCVclWkut9LH4g 方法ㄧ: void method_1(Mat &image) { double t1 = getTickCount(); int w = image.cols; int h = image.rows; for (int row = 0; row < h; row++) { for (int col = 0; col < w; col++) { Vec3b bgr = image.at(row, col); bgr[0] = 255 - bgr[0]; bgr[1] = 255 - bgr[1]; bgr[2] = 255 - bgr[2]; image.at(row, col) = bgr; } } double t2 = getTickCount(); double t = ((t2 - t1) / getTickFrequency()) * 1000; ostringstream ss; ss << "Execute time : " << std::fixed << std::setprecision(2) << t << " ms "; putText(image, ss.str(), Point(20, 20), FONT_HERSHEY_SIMPLEX, 0.75, Scalar(0, 0, 255), 2, 8); imshow("result", image); } 方法二: void method_2(Mat &image) { double t1 = getTickCount(); int w = image.cols; int h = image.rows; for (int row = 0; row < h; row++) { Vec3b* curr = image.ptr(row); for (int col = 0; col < w; col++) { Vec3b bgr = curr[col]; bgr[0] = 255 - bgr[0]; bgr[1] = 255 - bgr[1]; bgr[2] = 255 - bgr[2]; } } double t2 = getTickCount(); double t = ((t2 - t1) / getTickFrequency()) * 1000; ostringstream ss; ss << "Execute time : " << std::fixed << std::setprecision(2) << t << " ms "; putText(image, ss.str(), Point(20, 20), FONT_HERSHEY_SIMPLEX, 0.75, Scalar(0, 0, 255), 2, 8); imshow("result", image); } /* 除了上述的行指針遍歷方式，常見的行指針還有如下： CV_8UC1: 灰度图像 uchar* ptr = image.ptr(row_index); CV_8UC3: 彩色图像 Vec3b* ptr = image.ptr(row_index); CV_32FC1: 单通道浮点数图像 float* ptr = image.ptr(row_index); CV_32FC3: 三通道浮点数图像 Vec3f* ptr = image.ptr(row_index); */ 方法三: void method_3(Mat &image) { double t1 = getTickCount(); int w = image.cols; int h = image.rows; for (int row = 0; row < h; row++) { uchar* uc_pixel = image.data + row*image.step; for (int col = 0; col < w; col++) { uc_pixel[0] = 255 - uc_pixel[0]; uc_pixel[1] = 255 - uc_pixel[1]; uc_pixel[2] = 255 - uc_pixel[2]; uc_pixel += 3; } } double t2 = getTickCount(); double t = ((t2 - t1) / getTickFrequency()) * 1000; ostringstream ss; ss << "Execute time : " << std::fixed << std::setprecision(2) << t << " ms "; putText(image, ss.str(), Point(20, 20), FONT_HERSHEY_SIMPLEX, 0.75, Scalar(0, 0, 255), 2, 8); imshow("result", image); }