VLFeat - Documentation > vl_demo_sift_edge

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Documentation> vl_demo_sift_edge

# Source code for ``vl_demo_sift_edge.m

This file is located in the ``toolbox/demo folder in VLFeat package.

    % VL_DEMO_SIFT_EDGE  Demo: SIFT: edge treshold

    randn('state',0) ;
    rand('state',0) ;

    I = zeros(100,500) ;
    for i=[10 20 30 40 50 60 70 80 90]
      d = round(i/3) ;
      I(50-d:50+d,i*5) = 1 ;
    end
    I = 2*pi*8^2 * vl_imsmooth(I,8) ;
    I = single(255 * I) ;

    figure(1) ; clf ;
    imagesc(I) ; colormap gray ;
    axis equal ;  axis off ; axis tight ;
    hold on ;

    vl_demo_print('sift_edge_0') ;

    ter=[3.5 5 7.5 10] ;
    for te=ter
      f = vl_sift(I, ...
               'PeakThresh',   0,  ...
               'EdgeThresh',   te, ...
               'FirstOctave', -1  ) ;
      h1 = vl_plotframe(f) ;
      set(h1,'color','k','linewidth',3) ;
      h2 = vl_plotframe(f) ;
      set(h2,'color','y','linewidth',2) ;

      vl_demo_print(sprintf('sift_edge_%d', find(te==ter))) ;
      delete(h1) ;
      delete(h2) ;
    end