X is not a member of 'cv'异常解决

#include "opencv2/imgproc/imgproc.hpp"
  

(ofc, you have to link opencv_imgproc, too)

       #include "opencv2/opencv.hpp"
       convertro
       是opencv/core库里面的
       如果报下面的错：
       VideoTest.cpp:(.text+0x6f): undefined reference to `cv::VideoWriter::fourcc(char,char,char, char)'
       VideoTest.cpp:(.text+0xc3): undefined reference to `cv::VideoWriter::open(cv::String const&, int, double, cv::Size_<int>, bool)'
       VideoTest.cpp:(.text+0x103): undefined reference to `cv::namedWindow(cv::String const&, int)'
       VideoTest.cpp:(.text+0x146): undefined reference to `cv::VideoCapture::read(cv::_OutputArray const&)'
       VideoTest.cpp:(.text+0x1b1): undefined reference to `cv::imshow(cv::String const&, cv::_InputArray const&)'
       解决方法是：
   

        #include "opencv2/videoio.hpp"
        also, you don't seem to link to any of the required opencv libs, those are:
        opencv_core, opencv_videoio, opencv_highgui