A method, in an apparatus for position decoding, operates to extract a
sequence of positions from a sequence of images of a position-coding
pattern, as recorded by a sensor. The method, which may be embodied as a
computer program on a computer-readable storage medium, involves the
steps of retrieving at least one reference position (P1, P1'); and
extracting the sequence of positions solely by matching information
obtained from each of the images with a corresponding pattern reference
area (MA), which represents a known subset of the position-coding pattern
with a given, direct or indirect, spatial relation to the reference
position(s).