function imdb = bacteria_get_database_3(fmdDir, varargin)
opts.seed = 0 ;
opts = vl_argparse(opts, varargin) ;

rng(opts.seed, 'twister') ;

imdb.imageDir = fmdDir ;

cats = dir(imdb.imageDir) ;
cats = cats([cats.isdir] & ~ismember({cats.name}, {'.','..'})) ;
imdb.classes.name = {cats.name} ;
imdb.images.id = [] ;

for c=1:numel(cats)
  ims = dir(fullfile(imdb.imageDir, imdb.classes.name{c}, '*.tif'));
  % if there is more then 20 images, then take only first 20 images
  if numel(ims) > 20
    ims = ims(1:20);
  end
  %imdb.images.name{c} = fullfile(imdb.classes.name{c}, {ims.name}) ;
  imdb.images.name{c} = cellfun(@(S) fullfile(imdb.classes.name{c}, S), ...
    {ims.name}, 'Uniform', 0);
  imdb.images.label{c} = c * ones(1,numel(ims)) ;
  if numel(ims) < 20, error('ops') ; end
  sets = [1 * ones(1,2), 2 * ones(1,1), 3 * ones(1,17)] ;
  imdb.images.set{c} = sets(randperm(20)) ;
end
imdb.images.name = horzcat(imdb.images.name{:}) ;
imdb.images.label = horzcat(imdb.images.label{:}) ;
imdb.images.set = horzcat(imdb.images.set{:}) ;
imdb.images.id = 1:numel(imdb.images.name) ;

imdb.segments = imdb.images ;
imdb.segments.imageId = imdb.images.id ;
% there are no segment masks

% make this compatible with the OS imdb
imdb.meta.classes = imdb.classes.name ;
imdb.meta.inUse = true(1, numel(imdb.meta.classes)) ;
imdb.segments.difficult = false(1, numel(imdb.segments.id)) ;