Method for generating reference signal sequence using grouping is explained. Also provided are a medium comprising a basal medium supplemented with the serum-free supplement of the present invention. The stored products to be picked are placed onto the conveyor belt or directly into the order container upon actuation of the revolving belt. Non-uniform ink application, uneven pressure while rolling on the paper or pressing on the scanner surface and external dirt like oil and climatic variations in the moisture content of skin are some of the main causes for the ridges and valleys not to be imaged clearly. The actuator can move the touchpad laterally, or a separate surface member can be actuated.