the background the same process can also be used with an even higher degree of complexity in order now to be in a position to calculate the surface of each bit b in the code a definite surroundings area for each bit must be created in the code it must be ensured that the surface of the background is known before the code is added to the background this addition of the code to the background can be a procedure of superimposing two images the background which can be designated as a pattern sch is created in the following stages firstly according to fig4 f a ring r with the radii r 4 and r 3 is outlined in which r 4 r 3 gt r 1 r 2 applies whereby the sensitivity regarding the position of the longitudinal axis of the bottle is eliminated problems might otherwise arise if the centre point of the bottom of the bottle does not coincide with the centre point of the circle on which the code is situated in order therefore to ensure that the background ring completely encompasses each bit in the code the two images or ring surfaces are superimposed on each other fig4 f the second stage consists of cutting the pattern ring r into sectors s each with the angle u03b2 in which u03b2 u2266 u03b1 applies the sector angle u03b2 is therefore smaller than or equal to the angle u03b1 of a.