GetRandomEllipseImage.m

% GetRandomEllipseImage(K)
% generate a logical image with K overlapping ellipses
% 

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function bw=GetRandomEllipseImage(K)

IMSIZE=1000;
mu1=[500,500];

bw=logical(zeros(IMSIZE));

pts={};
ptsEdge={};
bValidEllipse=0;

while ~bValidEllipse
    for kk=1:K
        [pts{kk} ptsEdge{kk}] = GetRandomEllipsePts(mu1,IMSIZE);
    end
    
    % place each ellipse
    for kk=2:K
        ptsCombined=vertcat(pts{1:kk-1});
        idxK = 1+round((length(pts{kk})-1)*rand());
        idxCombined = 1+round((length(ptsCombined)-1)*rand());
        offset = ptsCombined(idxCombined,:)-pts{kk}(idxK,:);
        pts{kk} = pts{kk} + repmat(offset,[size(pts{kk},1) 1]);
        ptsEdge{kk} = ptsEdge{kk}+repmat(offset,[size(ptsEdge{kk},1) 1]);
    end
    idxPts={};
    for kk=1:K
        idxPts{kk}=sub2ind([1000,1000],pts{kk}(:,2),pts{kk}(:,1));
    end
    
    idxPtsOverlap=GetOverlap(idxPts);
    % make sure no ellipse is fully contained in another