c++ - OpenCV Error: Assertion failed <scn == 3 ::scn == 4> in unknown function, -

i read alot other solution still confused should mine...

#include <opencv2/objdetect/objdetect.hpp> #include <opencv2/highgui/highgui.hpp> #include <opencv2/imgproc/imgproc.hpp>  #include <iostream> #include <stdio.h>  using namespace std; using namespace cv;  int main(int argc, const char** argv) {     //create cascade classifier object used face detection     cascadeclassifier face_cascade;     //use haarcascade_frontalface_alt.xml library     face_cascade.load("haarcascade_frontalface_alt.xml");      //setup video capture device , link first capture device     videocapture capturedevice;     capturedevice.open(0);      //setup image files used in capture process     mat captureframe;     mat grayscaleframe;      //create window present results     namedwindow("outputcapture", 1);      //create loop capture , find faces     while (true)     {         //capture new image frame         capturedevice >> captureframe;          //convert captured image gray scale , equalize         cvtcolor(captureframe, grayscaleframe, cv_bgr2gray);         equalizehist(grayscaleframe, grayscaleframe);          //create vector array store face found         std::vector<rect> faces;          //find faces , store them in vector array         face_cascade.detectmultiscale(grayscaleframe, faces, 1.1, 3, cv_haar_find_biggest_object | cv_haar_scale_image, size(30, 30));          //draw rectangle found faces in vector array on original image         (int = 0; < faces.size(); i++)         {             point pt1(faces[i].x + faces[i].width, faces[i].y + faces[i].height);             point pt2(faces[i].x, faces[i].y);              rectangle(captureframe, pt1, pt2, cvscalar(0, 255, 0, 0), 1, 8, 0);         }          //print output         imshow("outputcapture", captureframe);          //pause 33ms         waitkey(33);     }     return 0; } 

this error

opencv error: assertion failed in unknown function

it seems error happened after "capturedevice >> captureframe;" please guide me, taking image camera.

it seems videocapture can't grab frame camera. add code check result of frame grabbing:

//create loop capture , find faces while (true) {     //capture new image frame     capturedevice >> captureframe;     if (captureframe.empty())     {         cout << "failed grab frame" << endl;         break;     }     ... 

if problem of videocapture check installed drivers camera.