function per = perspectives(filename,number)

if nargin < 2
    number = 4
end
    
structElement=strel('disk',3);

index=1;
eps=1e-10;
for alpha = 0:pi/number:pi-eps %rot. around x
    for beta = 0:pi/number:pi-eps %rot around y
        fprintf('alpha,beta: %d %d\n',alpha,beta); 
        per{index} = projection2d(filename,[alpha beta],1);
        per{index}=imclose(per{index},structElement);
        index = index + 1;
    end
end
return
