Documentation>vl_demo_sift_cmd

# Source code for ``vl_demo_sift_cmd.m

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

    % VL_DEMO_SIFT_CMD Demo: SIFT: test command line utility

    pfx = fullfile(vl_root,'results') ;
    vl_xmkdir(pfx) ;

    p_img = fullfile(vl_root,'data','box.pgm') ;
    p_low = fullfile(vl_root,'data','box.sift') ;
    p_txt = fullfile(pfx,'box.sift') ;
    p_tmp = fullfile(pfx,'box.tmp') ;

    I = imread(p_img) ;
    I = single(I) ;

    [f0,d0] = vl_ubcread(p_low) ;

    % --------------------------------------------------------------------
    %                                                        Test detector
    % --------------------------------------------------------------------

    [err,msg] = vl_demo_cmd('sift',['"' p_img '" --output=ascii://"' p_txt ...
                       '" --peak-thresh=3.4 --edge-thresh=10 --first-octave=-1']) ;
    if (err), error(msg) ; end

    data      = load(p_txt,'-ASCII') ;
    f1        = data(:,1:4)' ; f1(1:2,:) = f1(1:2,:) + 1 ;
    d1        = uint8(data(:,5:end)') ;
    [f,d]     = vl_sift(I,'FirstOctave',-1,'edgethresh',10,'peakthresh',3.4) ;

    disp(msg) ;

    [m0, sc0]  = vl_ubcmatch(d,d0) ;
    [m1, sc1]  = vl_ubcmatch(d,d1) ;
    [dr,perm]  = sort(sc0,'ascend') ;

    figure(1) ; clf ;
    imagesc(I) ; colormap gray ; hold on ;
    h = vl_plotframe(f) ;  set(h,'color','g','linewidth',4) ;
    h = vl_plotframe(f1) ; set(h,'color','b','linewidth',2) ;
    h = vl_plotframe(f0) ; set(h,'color','r','linewidth',1) ;

    legend('MATLAB','command line','original SIFT') ;

    axis equal ; axis off ; axis tight ;
    vl_demo_print('sift_cmd_1') ;

    figure(2) ; clf ;
    imagesc(I) ; colormap(gray(256)) ; hold on ;
    s      = m0(1,perm(1:20)) ;
    s0     = m0(2,perm(1:20)) ;
    [dr,a] = intersect(m1(1,:),s) ;
    s1     = m1(2,a) ;

    h = vl_plotsiftdescriptor(d(:,s),  f(:,s)  ) ; set(h,'color','g','linewidth',4) ;
    h = vl_plotsiftdescriptor(d1(:,s1),f1(:,s1)) ; set(h,'color','b','linewidth',2) ;
    h = vl_plotsiftdescriptor(d0(:,s0),f0(:,s0)) ; set(h,'color','r','linewidth',1) ;

    legend('MATLAB','command line','original SIFT') ;

    axis equal ; axis off ; axis tight ;
    vl_demo_print('sift_cmd_2') ;

    % --------------------------------------------------------------------
    %                                                      Test descriptor
    % --------------------------------------------------------------------

    tmp=f0' ; tmp(:,1:2) = tmp(:,1:2) - 1 ;
    save(p_tmp,'tmp','-ASCII') ;

    [err,msg] = vl_demo_cmd('sift',['"' p_img ...
                        '" --output "ascii://' p_txt ...
                        '" --read-frames "ascii://' p_tmp ...
                        '" -v']) ;
    disp(msg) ;

    data      = load(p_txt,'-ASCII') ;
    f1        = data(:,1:4)' ; f1(1:2,:) = f1(1:2,:) + 1 ;
    d1        = uint8(data(:,5:end)') ;
    [f,d]     = vl_sift(I,'FirstOctave',-1,'frames',f0,'verbose') ;

    [m0, sc0]  = vl_ubcmatch(d,d0) ;
    [m1, sc1]  = vl_ubcmatch(d,d1) ;
    [dr,perm]  = sort(sc0,'ascend') ;

    figure(3) ; clf ;
    imagesc(I) ; colormap(gray(256)) ; hold on ;
    h = vl_plotframe(f) ;  set(h,'color','g','linewidth',4) ;
    h = vl_plotframe(f1) ; set(h,'color','b','linewidth',2) ;
    h = vl_plotframe(f0) ; set(h,'color','r','linewidth',1) ;

    legend('MATLAB','command line','original SIFT') ;

    axis equal ; axis off ; axis tight ;
    vl_demo_print('sift_cmd_3') ;

    figure(4) ; clf ;
    imagesc(I) ; colormap(gray(256)) ; hold on ;
    s      = m0(1,perm(1:20)) ;
    s0     = m0(2,perm(1:20)) ;
    [dr,a] = intersect(m1(1,:),s) ;
    s1     = m1(2,a) ;

    h = vl_plotsiftdescriptor(d(:,s),  f(:,s)  ) ; set(h,'color','g','linewidth',4) ;
    h = vl_plotsiftdescriptor(d1(:,s1),f1(:,s1)) ; set(h,'color','b','linewidth',2) ;
    h = vl_plotsiftdescriptor(d0(:,s0),f0(:,s0)) ; set(h,'color','r','linewidth',1) ;

    legend('MATLAB','command line','original SIFT') ;

    axis equal ; axis off ; axis tight ;
    vl_demo_print('sift_cmd_4') ;