Method for calibrating a thermal printer

A method for calibrating a thermal printer, having a thermal head incorporating a plurality of energisable heating elements, comprises the step of supplying to the thermal printer a thermographic material m, a plurality of printer data P i each intended to be recorded as a pixel having a density Di, and default reference values for printing parameters comprising a value Pref for a reference printing power; and the step of printing a calibration pattern for the plurality of printer data P i , the calibration pattern comprising a multiple step density wedge such that a whole range of a relation Di (P i ) between the printer data P i and the density Di is covered. Further steps comprise measuring a density Dexp i for each patch of the density wedge of the calibration pattern in relation to the plurality of printer data P i and storing a first set S 1 =(Pref, P i , Dexp i ) in a first memory M 1 ; calculating, for a desired density Dwant j , a corresponding value Prefnew j for the reference printing power and storing a second set S 2 =(Dwant j , Prefnew j ) in a second memory M 2 ; calculating, for the desired density Dwant j , for each printer data P i a corresponding density Di and storing a third set S 3 =(Dwant j , Prefnew j , P i , Di) in a third memory M 3.