if ~exist('active_images'),
	active_images = ones(1,n_ima);
end;
n_act = length(active_images);
if n_act < n_ima,
   active_images = [active_images ones(1,n_ima-n_act)];
else
   if n_act > n_ima,
      active_images = active_images(1:n_ima);
   end;
end;

ind_active = find(active_images);

if prod(active_images == 0),
   disp('Error: There is no active image. Run Add/Suppress images to add images');
   break
end;