openCV中的Absdiff可以编译但显示黑色图像

Question

我一直在尝试使用 absdiff 来查找图像中的运动，但不幸的是它失败了，我是 OpenCV 的新手。编码应该使用 absdiff 来确定周围是否发生任何运动，但对于 diff1、diff2 和 motion，输出是一片漆黑。同时，next_mframe、current_mframe、prev_mframe显示灰度图像。而 result 显示清晰正常的图像。我以此为参考 http://manmade2.com/simple-home-surveillance-with-opencv-c-and-raspberry-pi/。我认为所有图像内存都加载了相同的帧并进行比较，这就解释了为什么它是一片漆黑。还有其他我想念的方法吗？我正在使用 RTSP 将相机 RAW 图像传递给 ROS.

    void imageCallback(const sensor_msgs::ImageConstPtr&msg_ptr){

    CvPoint center;
    int radius, posX, posY;

    cv_bridge::CvImagePtr cv_image;     //To parse image_raw from rstp
    try
    {
        cv_image = cv_bridge::toCvCopy(msg_ptr, enc::BGR8);
    }
    catch (cv_bridge::Exception& e)
    {
      ROS_ERROR("cv_bridge exception: %s", e.what());
      return;
    }

    frame = new IplImage(cv_image->image);    //frame now holding raw_image
    frame1 = new IplImage(cv_image->image); 
    frame2 = new IplImage(cv_image->image); 
    frame3 = new IplImage(cv_image->image); 

     matriximage = cvarrToMat(frame);
     cvtColor(matriximage,matriximage,CV_RGB2GRAY);  //grayscale

     prev_mframe = cvarrToMat(frame1);
     cvtColor(prev_mframe,prev_mframe,CV_RGB2GRAY);  //grayscale
     current_mframe = cvarrToMat(frame2);
     cvtColor(current_mframe,current_mframe,CV_RGB2GRAY);  //grayscale
     next_mframe = cvarrToMat(frame3);
     cvtColor(next_mframe,next_mframe,CV_RGB2GRAY);  //grayscale

     // Maximum deviation of the image, the higher the value, the more motion is allowed
    int max_deviation = 20;

    result=matriximage;

    //rellocate image in right order
    prev_mframe = current_mframe;
    current_mframe = next_mframe;
    next_mframe = matriximage;
    //motion=difflmg(prev_mframe,current_mframe,next_mframe);

    absdiff(prev_mframe,next_mframe,diff1); //Here should show black and white image
    absdiff(next_mframe,current_mframe,diff2);
    bitwise_and(diff1,diff2,motion);
    threshold(motion,motion,35,255,CV_THRESH_BINARY);
    erode(motion,motion,kernel_ero);


    imshow("Motion Detection",result);
    imshow("diff1",diff1);  //I tried to output the image but its all black
    imshow("diff2",diff2);  //same here, I tried to output the image but its all black
    imshow("diff1",motion);
    imshow("nextframe",next_mframe);
    imshow("motion",motion);

    char c =cvWaitKey(3);  }

Answer 1

我将 cv_bridge 方法更改为 VideoCap，它似乎运行良好，cv_bridge 即使我将 IplImage 更改为 Mat 格式也无法保存图像。或许还有其他的方法，但目前我还是先用这个方法。

VideoCapture cap(0); 
Tracker(void)
{
    //check if camera worked
    if(!cap.isOpened())
    {
        cout<<"cannot open the Video cam"<<endl;
    }
    cout<<"camera is opening"<<endl;

    cap>>prev_mframe;
    cvtColor(prev_mframe,prev_mframe,CV_RGB2GRAY);  // capture 3 frame and convert to grayscale
    cap>>current_mframe;
    cvtColor(current_mframe,current_mframe,CV_RGB2GRAY);  
    cap>>next_mframe;
    cvtColor(next_mframe,next_mframe,CV_RGB2GRAY); 

    //rellocate image in right order
    current_mframe.copyTo(prev_mframe);
    next_mframe.copyTo(current_mframe);
    matriximage.copyTo(next_mframe);

    motion = diffImg(prev_mframe, current_mframe, next_mframe);
}

openCV中的Absdiff可以编译但显示黑色图像

Absdiff in openCV can compile but show black image

c++

opencv

ros