OpenCV 错误：断言失败 (buf.data && buf.isContinu()) in cv：：imdecode_， file ..\..\..\..\openCV

我正试图在visualstudio 2010中使用opencv和curl从url加载图像。在运行代码时，我遇到了上述错误。这个错误是什么意思？如何更正我的代码。这是我的代码

#include "curl/curl.h" // has to go before opencv headers
#include <iostream>
#include <vector>
using namespace std;
#include <opencv2/opencv.hpp>
using namespace cv;
//curl writefunction to be passed as a parameter
// we can't ever expect to get the whole image in one piece,
// every router / hub is entitled to fragment it into parts
// (like 1-8k at a time),
// so insert the part at the end of our stream.
size_t write_data(char *ptr, size_t size, size_t nmemb, void *userdata)
{
    vector<uchar> *stream = (vector<uchar>*)userdata;
    size_t count = size * nmemb;
    stream->insert(stream->end(), ptr, ptr + count);
    return count;
}
//function to retrieve the image as cv::Mat data type
cv::Mat curlImg(const char *img_url, int timeout=10)
{
    vector<uchar> stream;
    CURL *curl = curl_easy_init();
    curl_easy_setopt(curl, CURLOPT_URL, img_url); //the img url
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data); // pass the writefunction
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, &stream); // pass the stream ptr to the writefunction
    curl_easy_setopt(curl, CURLOPT_TIMEOUT, timeout); // timeout if curl_easy hangs, 
    CURLcode res = curl_easy_perform(curl); // start curl
    curl_easy_cleanup(curl); // cleanup
    return imdecode(stream, -1); // 'keep-as-is'
}
int main(void)
{
    Mat image = curlImg("http://pimg.tradeindia.com/01063301/b/1/CRO-Oscilloscope.jpg");
 //   if (image.empty())
 //       return -1; // load fail
    namedWindow( "Image output", CV_WINDOW_AUTOSIZE );
    if (!image.empty())
		imshow("Image output",image); // here's your car ;)
    waitKey(0); // infinite
}

谢谢你的帮助。