Ubuntu下使用qtcreator，opencv3.0调用函数 connectedComponents报错。

[weixin_39381465]

void MainWindow::on_AOI_clicked()
{
    cv::namedWindow("noise");
    cv::namedWindow("output");
    cv::Mat pattern;//(653,994,CV_8UC3,cv::Scalar(100,100,100));
    cv::Mat aux,thr30,thr140;
    cv::Mat clean = cv::imread("/home/kylin/图片/2.jpg");
    cv::blur(clean,pattern,cv::Size(clean.cols/3,clean.cols/3));
    //cv::imshow("pattern",pattern);//背景近似值
    aux = pattern - clean;
    cv::medianBlur(aux,noise,3);//除噪
    cv::threshold(aux,thr30,30,255,cv::THRESH_BINARY);
    cv::threshold(aux,thr140,140,255,cv::THRESH_BINARY_INV);//二值化
    //cv::imshow("clean",thr30);
    cv::imshow("noise",thr140);
    thr140.convertTo(thr140,CV_8UC1);//转换为8位格式
    cv::imshow("aux",thr140);
    cv::Mat labels;
    int num_objects = cv::connectedComponents(thr140,labels,8,CV_32S);//此处过不去。
    //int num_objects = 6;
    if(num_objects < 2)
    {
        qDebug()<< "No objects detected" << endl;
    }
    else
        qDebug()<< "Number of objects detected: "<< num_objects - 1 << endl;
    //创建彩色目标的输出图像
    cv::Mat output = cv::Mat::zeros(thr140.rows,thr140.cols,CV_8UC3);
    cv::RNG rng(0xFFFFFFFF);
    for(int i=1;i < num_objects;i++)
    {
        cv::Mat mask = labels==i;
        output.setTo(randomColor(rng),mask);
    }
    cv::imshow("output",output);

终端提示报错信息如下。不知道是环境搭建有问题还是函数调用问题。麻烦大家，有没有碰到过类似问题的帮我想想办法。
OpenCV Error: Assertion failed (L.channels() == 1 && I.channels() == 1) in connectedComponents_sub1, file /build/opencv-zcaJjh/opencv-3.2.0+dfsg/modules/imgproc/src/connectedcomponents.cpp, line 1657
terminate called after throwing an instance of 'cv::Exception'
what(): /build/opencv-zcaJjh/opencv-3.2.0+dfsg/modules/imgproc/src/connectedcomponents.cpp:1657: error: (-215) L.channels() == 1 && I.channels() == 1 in function connectedComponents_sub1