function create_db(db_file)
    conn = sqlite(db_file,'create');
    sql=['CREATE TABLE images( ', ...
        table_images_desc(),...
    ');'];
%        'bb TEXT,', ...
%        'data TEXT', ...    
    execute(conn,sql);
    sql=['CREATE VIRTUAL TABLE rtr USING rtree( ', ...
        'cnt_id,', ...
        'xmin , ', ...
        'xmax, ', ...
        'ymin,', ...
        'ymax,', ...
        '+id TEXT,', ...
        '+ref_nr INTEGER,',...
        '+yawc REAL',...
    ');'];
    execute(conn,sql);
    close(conn);
end