Patent ID: 7567706

Claim:
A method for processing digital data from a row-column structured multi-color bitmap image representation, comprising the steps of: a) reducing said bitmap image representation from an initial number of colors to a reduced number of colors to form a reduced bitmap, each color of the reduced number of colors in the reduced bitmap corresponding to a respective subset of bitmap bits of a set of bitmap bits; b) for at least one subset of said subsets, performing the following steps: b1) performing a row-wise XOR operation on a first and second row of each pair of successive rows of said reduced bitmap to generate a resultant row that replaces said first row, yielding a first intermediate result after said row-wise XOR operation has been performed on all pairs of rows of the reduced bitmap, b2) coding said first intermediate result into a bit string yielding a second intermediate compression result by repeatedly performing the following mapping steps: b2a) mapping a byte having one or more ‘1’ bits to a bit value of ‘1’, and b2b) mapping a byte consisting of ‘0’ bits to a bit value of ‘0’, b3) applying an additional compression to said second intermediate compression result to yield an additional compression result.