function[obj] = preprocess(obj);

progressbar = waitbar(0, 'Preprocessing subjects...');
p= get(progressbar, 'Position'); p(2)=p(2)+100;
set(progressbar,'Position', p, 'Color', [1 1 1]);
t = get(get(progressbar, 'Children'), 'Title');
set(t, 'FontSize', 15, 'FontWeight', 'bold', 'FontName', 'Tahoma');
set(progressbar,'Visible','on');


for s = 1:length(obj.subjects)
    waitbar(s/length(obj.subjects), progressbar, sprintf('Preprocessing data for subject %d...', s));
    obj.subjects(s) = obj.subjects(s).preprocess(obj.settings);
    
end

close(progressbar);
end