Thermal printer and ink ribbon used therewith

摘要

A gradation correction data used in correcting the gradation of the printed image is recorded on the leader film of the ink ribbon in a form of optically readable marks. Then the ink ribbon is set in a thermal printer, the marks are read out by an optical sensor to obtain the gradation correction data. Then, the gradation correction of the image data to be printed is carried out by referring to the correction data thus obtained prior to the actual printing of the image data.