Documentation>vl_demo_covdet

# Source code for ``vl_demo_covdet.m

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

    % VL_DEMO_COVDET Demo: VL_COVDET()

    % --------------------------------------------------------------------
    %                                                               Basics
    % --------------------------------------------------------------------

    im = vl_impattern('roofs1') ;
    im = im(end-128:end,128:320,:) ;

    figure(1) ; clf ;
    image(im) ; axis image off ;
    vl_demo_print('covdet_basic_image') ;

    imgs = im2single(rgb2gray(im)) ;
    frames = vl_covdet(imgs, 'verbose') ;

    hold on ;
    vl_plotframe(frames) ;
    vl_demo_print('covdet_basic_frames') ;

    % --------------------------------------------------------------------
    %                                                    Affine adaptation
    % --------------------------------------------------------------------

    frames = vl_covdet(imgs, 'estimateAffineShape', true, 'verbose') ;

    figure(2) ; clf ;
    image(im) ; axis image off ; hold on ;
    vl_plotframe(frames) ;
    vl_demo_print('covdet_affine_frames',.8) ;

    % --------------------------------------------------------------------
    %                                              Estimating orientations
    % --------------------------------------------------------------------

    frames = vl_covdet(imgs, 'estimateOrientation', true, 'verbose') ;

    figure(3) ; clf ;
    image(im) ; axis image off ; hold on ;
    vl_plotframe(frames) ;
    vl_demo_print('covdet_oriented_frames',.8) ;

    % --------------------------------------------------------------------
    %                                                   Extracting patches
    % --------------------------------------------------------------------

    [frames, patches] = vl_covdet(imgs, 'descriptor', 'patch') ;

    figure(4) ; clf ;
    w = sqrt(size(patches,1)) ;
    vl_imarraysc(reshape(patches(:,1:10*10), w,w,[])) ;
    axis image off ; hold on ; colormap gray ;
    vl_demo_print('covdet_patches') ;

    [frames, patches] = vl_covdet(imgs, ...
                                  'descriptor', 'patch' ,...
                                  'estimateAffineShape', true, ...
                                  'estimateOrientation', false) ;

    figure(5) ; clf ;
    w = sqrt(size(patches,1)) ;
    vl_imarraysc(reshape(patches(:,1:10*10), w,w,[])) ;
    axis image off ; hold on ; colormap gray ;
    vl_demo_print('covdet_affine_patches') ;

    % --------------------------------------------------------------------
    %                                                  Different detectors
    % --------------------------------------------------------------------

    names = {'DoG', 'Hessian', ...
             'HarrisLaplace', 'HessianLaplace', ...
             'MultiscaleHarris', 'MultiscaleHessian'} ;
    figure(6) ; clf ;
    for i = 1:numel(names)
      frames = vl_covdet(imgs, 'method', names{i}) ;

      vl_tightsubplot(3,2,i, 'margintop',0.025, 'marginright', 0.01) ;
      imagesc(im) ; axis image off ;
      hold on ;
      vl_plotframe(frames) ;
      title(names{i}) ;
    end

    vl_figaspect(3/4) ;
    vl_demo_print('covdet_detectors',.9) ;

    % --------------------------------------------------------------------
    %                                                        Custom frames
    % --------------------------------------------------------------------

    delta = 15 ;
    xr = delta:delta:size(im,2)-delta+1 ;
    yr = delta:delta:size(im,1)-delta+1 ;
    [x,y] = meshgrid(xr,yr) ;
    frames = [x(:)'; y(:)'] ;
    frames(end+1,:) = delta/2 ;

    [frames, patches] = vl_covdet(imgs, ...
                                  'frames', frames, ...
                                  'estimateAffineShape', true, ...
                                  'estimateOrientation', true) ;

    figure(7) ; clf ;
    imagesc(im) ;
    axis image off ; hold on ; colormap gray ;
    vl_plotframe(frames) ;
    vl_demo_print('covdet_custom_frames',.8) ;

    % --------------------------------------------------------------------
    %                                                         Scale spaces
    % --------------------------------------------------------------------

    [frames, descrs, info] = vl_covdet(imgs) ;

    figure(8) ; clf ;
    vl_plotss(info.gss) ;
    colormap gray ;
    vl_figaspect(2) ;
    vl_demo_print('covdet_gss',.8) ;

    figure(9) ; clf ;
    vl_plotss(info.css) ;
    colormap gray ;
    vl_figaspect(2) ;
    vl_demo_print('covdet_css',.8) ;

    figure(10) ; clf ;
    subplot(1,2,1) ;
    hist([info.peakScores],10) ;
    xlabel('Peak Score') ;
    ylabel('Occurences') ;
    grid on ;

    subplot(1,2,2) ;
    hist([info.edgeScores],10) ;
    xlabel('Edge Score') ;
    ylabel('Occurences') ;
    grid on ;

    vl_figaspect(2) ;
    vl_demo_print('covdet_scores',.9) ;