function visualizemodel(model,compid)

if nargin<2
    compid = 1:length(model.components);
end

pad = 2;
bs = 20;

for i = compid
    c = model.components{i};
    numparts = length(c);
    
    Nmix = zeros(1,numparts);
    for k = 1:numparts
        Nmix(k) = length(c(k).filterid);
    end
    
    for k = 2:numparts
        part = c(k);
        anchor = zeros(Nmix(k),2);
        for j = 1:Nmix(k)
            def = model.defs(part.defid(j));
            anchor(j,:) = [def.anchor(1) def.anchor(2)];
        end
    end
    
    part = c(1);
    % part filter
    w = model.filters(part.filterid(1)).w;
    w = foldHOG(w);
    scale = max(abs(w(:)));
    p = HOGpicture(w, bs);
    p = padarray(p, [pad pad], 0);
    p = uint8(p*(255/scale));
    % border
    p(:,1:2*pad) = 128;
    p(:,end-2*pad+1:end) = 128;
    p(1:2*pad,:) = 128;
    p(end-2*pad+1:end,:) = 128;
    im = p;
    startpoint = zeros(numparts,2);
    startpoint(1,:) = [0 0];
    
    partsize = zeros(numparts,1);
    partsize(1) = size(p,1);
    
    for k = 2:numparts
        part = c(k);
        parent = c(k).parent;
        
        % part filter
        w = model.filters(part.filterid(1)).w;
        w = foldHOG(w);
        scale = max(abs(w(:)));
        p = HOGpicture(w, bs);
        p = padarray(p, [pad pad], 0);
        p = uint8(p*(255/scale));
        % border
        p(:,1:2*pad) = 128;
        p(:,end-2*pad+1:end) = 128;
        p(1:2*pad,:) = 128;
        p(end-2*pad+1:end,:) = 128;
        
        % paste into root
        def = model.defs(part.defid(1));
        
        x1 = (def.anchor(1)-1)*bs+1 + startpoint(parent,1);
        y1 = (def.anchor(2)-1)*bs+1 + startpoint(parent,2);
        
        [H W] = size(im);
        imnew = zeros(H + max(0,1-y1), W + max(0,1-x1));
        imnew(1+max(0,1-y1):H+max(0,1-y1),1+max(0,1-x1):W+max(0,1-x1)) = im;
        im = imnew;
        
        startpoint = startpoint + repmat([max(0,1-x1) max(0,1-y1)],[numparts,1]);
        
        x1 = max(1,x1);
        y1 = max(1,y1);
        x2 = x1 + size(p,2)-1;
        y2 = y1 + size(p,1)-1;
        
        startpoint(k,1) = x1 - 1;
        startpoint(k,2) = y1 - 1;
        
        im(y1:y2, x1:x2) = p;
        partsize(k) = size(p,1);
    end
    
    % plot parts
    figure,imagesc(im);
    colormap gray;
    axis equal; axis off;
    drawnow;
    title(sprintf('Component %d',i));
    hold on;
    %     % plot connections
    for k = 2:numparts
        parent = c(k).parent;
        sx = startpoint(k,1)+partsize(k)/2;
        endx = startpoint(parent,1)+partsize(parent)/2;
        sy = startpoint(k,2)+partsize(k)/2;
        endy = startpoint(parent,2)+partsize(parent)/2;
        plot([sx endx],[sy endy],'r','linewidth',2);
    end 
end


function f = foldHOG(w)
% f = foldHOG(w)
% Condense HOG features into one orientation histogram.
% Used for displaying a feature.

f=max(w(:,:,1:9),0)+max(w(:,:,10:18),0)+max(w(:,:,19:27),0);

function im = HOGpicture(w, bs)
% HOGpicture(w, bs)
% Make picture of positive HOG weights.

% construct a "glyph" for each orientaion
bim1 = zeros(bs, bs);
bim1(:,round(bs/2):round(bs/2)+1) = 1;
bim = zeros([size(bim1) 9]);
bim(:,:,1) = bim1;
for i = 2:9,
    bim(:,:,i) = imrotate(bim1, -(i-1)*20, 'crop');
end

% make pictures of positive weights bs adding up weighted glyphs
s = size(w);
w(w < 0) = 0;
im = zeros(bs*s(1), bs*s(2));
for i = 1:s(1),
    iis = (i-1)*bs+1:i*bs;
    for j = 1:s(2),
        jjs = (j-1)*bs+1:j*bs;
        for k = 1:9,
            im(iis,jjs) = im(iis,jjs) + bim(:,:,k) * w(i,j,k);
        end
    end
end