来自网络摄像头的阈值图像

Question

I am teaching myself OpenCV for a work project that will eventually involve object tracking and such, and I'm just trying to familiarize myself with the basics right now. I have a chunk of code that's meant to simply grab images from my webcam, convert them to grayscale and threshold them, and print them out to a window. I keep getting this error:

"cannot convert parameter 1 from 'cv::Mat' to 'const CvArr *'"

with this code:

#include <opencv2/opencv.hpp>
#include <opencv2/highgui/highgui.hpp>

using namespace cv;

int main()
{
    Mat img;
    VideoCapture cap(0);

    while (true)
    {
        cap >> img;

        Mat tHold;
        cvtColor(img, tHold, CV_BGR2GRAY);
    cvThreshold(tHold, tHold, 50, 255, CV_THRESH_BINARY);

        imshow("Thresholded Image", tHold);
        waitKey(1);
    }

    return 0;
}

The thing is that other functions seem to work, like Canny(), etc...I just can't get thresholding to work. Thoughts? Thanks!

Answer 1

You are using the function cvThreshold from the C interface of OpenCV. Whereas the input images are of type cv::Mat which are from the C++ interface.

The corresponding C++ function of cvThreshold is cv::threshold . Just replace cvThreshold with cv::threshold .