1. Method for determining the length of a queue of objects in a predefined region having at least one entrance and at least one exit, comprising the steps of: a) determining with the aid of at least one first image sensor a specific entry signature E of each object entering the predefined region through the at least one entrance; b) storing the specific entry signature E in an entry list of a calculation unit, each entry signature E being provided with an index value i reflecting the temporal sequence of the entries, and a value L reflecting the length of the queue of the objects being increased by one; c) determining with the aid of at least one second image sensor a specific exit signature A of an object exiting the predefined region through the at least one exit; d) storing the specific exit signature A in an exit list of a calculation unit as exit signature A 0 with index value j=0, the index value of exit signatures A j already present in the exit list respectively being increased by one, and the exit signatures A j which have an index value j that is greater than a predetermined value M being deleted from the exit list; e) calculating similarity values C n for −N≦n≦+N with the aid of the calculation unit, N being a predetermined value which defines a specific number N of entry signatures of objects which, before or after the object with the entry signature E L whose exit is next expected on the basis of the length of the queue L, will exit or have already exited the predefined region, similarity metrics U mn respectively being calculated between an exit signature A m and an entry signature E L+m+n , m running from 0 to M, and added to C n ; f) decrementing the value L by the value one; g) correcting the value L by comparing the similarity values C n with the similarity value C 0 , and correcting the value L by adding the index value x given the presence of a value C x with index value n=x that indicates a higher similarity than the similarity value C 0 .