A printing method in which a pixel is resolved into a matrix and the gradation of a picture is variably set by dots printed in each pixel. The method includes a line setting step of setting a print density for lines corresponding to the main scanning direction along which dots are arrayed, and a dot-based...http://www.google.de/patents/US6007175?utm_source=gb-gplus-sharePatent US6007175 - Picture printing method and device printing pixels in which columns of dots are printed at different intensity levels
