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I want to select the staff lines as individual blobs in either of these images:

enter image description here enter image description here

Is this possible?

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  • $\begingroup$ May be you should add 1 more image marked by the regions you want to detect! It is very difficult to understand now:( $\endgroup$ – Balaji R Jun 4 '15 at 5:25
  • $\begingroup$ The regions should be the 5 staff lines. $\endgroup$ – John Jun 4 '15 at 5:31
  • $\begingroup$ What exactly is staff line? Can you make some marking in paint & upload it? $\endgroup$ – Balaji R Jun 4 '15 at 5:33
  • $\begingroup$ The regions that I want to select are shown in this image (roughly, I selected them manually): i.imgur.com/4bpZLNJ.png It's ok if other blobs are getting selected too (I can filter them by their area afterwards). $\endgroup$ – John Jun 4 '15 at 5:40
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    $\begingroup$ Is it your problem solved? Please mark as answer if this solves your problem. $\endgroup$ – Balaji R Jun 11 '15 at 6:04
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Here is a simple steps in c++ to identify the Objects you want to detect! Hope this solves your problem!


void main()
{
    Mat mSource_Bgr,mSource_Gray,mSmoothed,mEdge,mThres;
    mSource_Bgr= imread(FileName_S.c_str(),IMREAD_COLOR);
    cvtColor(mSource_Bgr,mSource_Gray,COLOR_BGR2GRAY);

    medianBlur(mSource_Gray,mSmoothed,5); /*Just to smooth the Edges*/
/*This is for Automatically calculating the Canny Threshold values*/
    double CannyAccThresh = threshold(mSmoothed,mThres,0,255,CV_THRESH_BINARY|CV_THRESH_OTSU);
    double CannyThresh = 0.1 * CannyAccThresh;

    Canny(mSmoothed,mEdge,CannyThresh,CannyAccThresh); 

    Mat kernal_E,kernal_D;
    int erosion_size=2,dilation_size=2;
    kernal_E= getStructuringElement( MORPH_RECT,Size( 2*erosion_size + 1, 2*erosion_size+1 ),
                                       Point( erosion_size, erosion_size ) );
    kernal_D= getStructuringElement( MORPH_RECT,Size( 2*dilation_size + 1, 2*dilation_size+1 ),
                                       Point( dilation_size, dilation_size ) );
    dilate(mEdge,mEdge,kernal_D);//Just to make sure all the Edges are closed
    erode(mEdge,mEdge,kernal_E);

    imshow("mCanny_Edge",mEdge);
    imwrite(FileName_S+ "mCanny_Edge.bmp",mEdge);

enter image description here

    vector<vector<Point> > contours;
    vector<Vec4i> hierarchy;
    /// Find contours
    findContours( mEdge.clone(), contours, hierarchy, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE, Point(0, 0) );
    /// Approximate contours to polygons + get bounding rects and circles
    vector<vector<Point> > contours_poly( contours.size() );
    for( size_t i = 0; i < contours.size(); i++ )
    { 
        approxPolyDP( Mat(contours[i]), contours_poly[i], 1, true );
    }

    for (int i = 0; i < contours_poly.size(); i++)
    {
        if(contours_poly[i].size()>100)//Just a filter You can add more here
            drawContours(mSource_Bgr,contours_poly,i,Scalar(0,255,0),2);
    }
    imshow("mResult",mSource_Bgr);

enter image description here }

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