在Visual Studio C ++中使用OpenCV完成图像处理时，帧会大幅减少

Question

我正在使用Visual Studio 2017和OpenCV 3.1。没有任何图像处理，帧速率非常好，但是一旦我进行图像处理，只要转换为灰度图像并应用高斯模糊，帧速率就会急剧下降。 Python中的相同代码几乎以实时帧速率运行（不应该C ++比Python快）。这是我的代码。

#include "opencv2\core\core.hpp"
#include "opencv2\imgproc\imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"
#include <iostream>

using namespace cv;
using namespace std;
Mat processed_frame;

Mat imageProcessing(Mat frame_proc) {
  cvtColor(frame_proc, processed_frame, COLOR_BGR2GRAY);
  medianBlur(processed_frame, processed_frame, 5);
  GaussianBlur(processed_frame, processed_frame, Size(21, 21), 0);
  threshold(processed_frame, processed_frame, 127, 255, 0);
  cv::Mat structuringElement5x5 = cv::getStructuringElement(cv::MORPH_RECT, cv::Size(5, 5));
  for (unsigned int i = 0; i < 5; i++) {
    cv::dilate(processed_frame, processed_frame, structuringElement5x5);
  }
  for (unsigned int j = 1; j < 2; j++) {
    erode(processed_frame, processed_frame, structuringElement5x5);
  }
  return (processed_frame);
}

int main() {
  Mat frame;
  Mat img3;
  VideoCapture cap("/path/to/Video/File");

  if (!cap.isOpened()) {
    cout << "Cannot open file" << endl;
    return -1;  
  }
  bool bSuccess = cap.read(frame);
  while (bSuccess) {
    cap >> frame;
    frame = imageProcessing(frame);*IF I COMMENT THIS LINE, FRAME RATE IS VERY GOOD
    imshow("VideoCapture", frame);
    cap.set(CV_CAP_PROP_FPS, 25);
    if (waitKey(1) == 27) {
        break;
    }
  }
return 0;
}