Patent ID: 6201901
Filing Date: 2001-03-13
Classification: G06K

Abstract:
A method of decoding randomized information printed on a printed medium in the form of a bitmap of rows and columns of data pixels representing encoded data bits, each of said data pixels being either a first or second color, said printed medium further having other printed information thereon, comprising the steps of:scanning said printed medium to digitize said bitmap and said other information;formatting said bitmap and said other information to a pixel based grayscale representation;setting the threshold intensity level based on said grayscale representation such that pixels above said threshold correspond to said first color and pixels below said threshold correspond to said second color;determining the row and column boundaries by determining the number of first color pixels in each row and each column of the scanned printed medium, and sequentially comparing the number of first pixels in each row and column, respectively, to a predetermined threshold;determining the skew angle of said digitized bitmap;deskewing said digitized bitmap so that said skew angle is reduced to substantially zero;cropping said digitized bitmap;reading out binary data from said digitized bitmap in a predetermined pattern to produce a one-dimensional array of digital data;derandomizing said one-dimensional array of digital data; anderror-correcting the derandomized one-dimensional array of digital data to produce a substantially error-free digital representation of the encoded information.