VLFeat - Documentation > vl_demo_sift_peak

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Documentation> vl_demo_sift_peak

# Source code for ``vl_demo_sift_peak.m

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

    % VL_DEMO_SIFT_PEAK  Demo: SIFT: peak treshold

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

    I = double(rand(100,500) <= .005) ;
    I = (ones(100,1) * linspace(0,1,500)) .* I ;
    I(:,1) = 0 ; I(:,end) = 0 ;
    I(1,:) = 0 ; I(end,:) = 0 ;
    I = 2*pi*4^2 * vl_imsmooth(I,4) ;
    I = single(255 * I) ;

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

    vl_demo_print('sift_peak_0') ;

    tpr = [0 10 20 30] ;
    for tp=tpr
      f = vl_sift(I, ...
               'PeakThresh',   tp,    ...
               'EdgeThresh',   10000, ...
               '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_peak_%d',find(tp==tpr))) ;
      delete(h1) ;
      delete(h2) ;
    end