Patent ID: 7650033

Claim:
A method of compressing a digital ink input including a sequence of strokes input at an input device of a processing system, the method comprising the steps of, carried out by a processor of the processing system: representing each stroke input at the input device as a series of digital words representing x and y co-ordinates; expressing at least one reference co-ordinate of each stroke in absolute terms; and expressing a co-ordinate other than the at least one reference co-ordinate as an offset from a preceding co-ordinate, wherein the co-ordinate other than the at least one reference co-ordinate is represented as a combination of an estimate determined from the previous m co-ordinates and a residual error value, and the estimate is calculated from the previous m co-ordinates using the formula: α ~ n = ∑ i = 1 m ⁢ c i ⁢ α n - i where c i are coefficients selected to model characteristics of the digital ink, and α represents either an x or a y co-ordinate.