OpenCV cvCvtColor not linked? - opencv

Question

I'm new to openCV, and I finally got it to open a window and show the webcam output.
I'm now trying to convert frames to greyscale before displaying them. Unfortunately, I get the following error every time I try to compile. error: ‘cvCvtColor’ was not declared in this scope I'm using the following line to compile
g++ main.cpp -lopencv_core -lopencv_imgproc -lopencv_highgui -lopencv_objdetect -o camera
Am I linking my code incorrectly? Here's the full code listing. Sorry for my formatting issues!
#include "opencv2/objdetect/objdetect.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/core/core.hpp"
#include <stdio.h>
#include <unistd.h>
IplImage* getCameraFrame(CvCapture* &camera)
{
IplImage *frame;
int w, h;
// If the camera hasn't been initialized, then open it.
if (!camera) {
printf("Acessing the camera ...\n");
camera = cvCreateCameraCapture( 0 );
if (!camera) {
printf("Couldn't access the camera.\n");
exit(1);
}
// Try to set the camera resolution to 320 x 240.
cvSetCaptureProperty(camera, CV_CAP_PROP_FRAME_WIDTH, 320);
cvSetCaptureProperty(camera, CV_CAP_PROP_FRAME_HEIGHT, 240);
// Get the first frame, to make sure the camera is initialized.
frame = cvQueryFrame( camera );
if (frame) {
w = frame->width;
h = frame->height;
printf("Got the camera at %dx%d resolution.\n", w, h);
}
// Wait a little, so that the camera can auto-adjust its brightness.
sleep(1); // (in milliseconds)
}
// Wait until the next camera frame is ready, then grab it.
frame = cvQueryFrame( camera );
if (!frame) {
printf("Couldn't grab a camera frame.\n");
exit(1);
}
return frame;
}
int main(int argc, char* argv[])
{
cvNamedWindow( "Example2", CV_WINDOW_AUTOSIZE );
CvCapture* capture = cvCreateCameraCapture( 0 );
IplImage* frame;
while(1) {
frame = cvQueryFrame( capture );
if( !frame ) break;
cvCvtColor(frame, frame, CV_RGB2GRAY);
cvShowImage( "Example2", frame );
char c = cvWaitKey(33);
if( c == 27 ) break;
}
cvReleaseCapture( &capture );
cvDestroyWindow( "Example2" );
return 0;
}

Answer 1

you're using the headers for the c++ api, but code from the deprecated c-api ( please don't !! ).
cv::VideoCapture cap(0);
while(cap.IsOpened()) {
cv::Mat f,g;
if ( ! cap.read(f) ) break;
cv::cvtColor(f, g, CV_RGB2GRAY);
cv::imshow("lalala",g);
if ( waitKey(10) == 27 ) break;
}
return 0;