Patent ID: 7190385

Claim:
Method of generating a sharpened image on a printing material in a thermal printer which comprises an internal thermal model module that converts input values into power values for each element of a thermal head and for each printing cycle, comprising the steps of: defining a function F(Mtw, b, c, d . . . ) wherein Mtw is a matrix of wanted temperature values for each of the heating elements of a thermal head and for all printing cycles, wherein at least a subset of parameters b, c, d . . . influences the behaviour of the function along the direction of said thermal head and a subset of said parameters b, c, d influences the behaviour of the function in a direction in which said printing material is transported past said thermal head, defining a matching function Fm=aMtw+F(Mtw, b, c, d, . . . ) with a=1−c; determining optimal values aopt, bopt, copt, dopt, . . . for said parameters a, b, c, d, . . . so that Fm(aopt, bopt, copt, dopt . . . ) simulates the behaviour of said printer applying values Mtwc to said internal thermal model, said values Mtwc being equal to 1/aopt*(Mtw-F(Mtw, bopt, copt, dopt, . . . )).