PURPOSE: To enhance resolution of images and obtain high image quality, by a method wherein matrices in which the sizes and the arrangement of halftone dots are appropriately specified are provided adjacently to and in parallel to each other on a base sheet by using a thermal transfer ink.

CONSTITUTION: The matrices in which the sizes and the arrangement of halftone dots are appropriately specified are provided ajacently to and in parallel to each other on the base sheet by using a thermal transfer ink. Since the matrix consisting of a set of dots and the matrix consisting of halftone dots can make one- to-one correspondence with each other, it is possible to easily refer to a dither matrix by a dither method when determining the sizes and the arrangement of the halftone dots, and the dither matrix can be functionally transformed by the sizes and the arrangement of the halftone dots. By the application of these, it is possible to enhance the gradation characteristics of image quality obtained by thermal transfer recording or to increase the resolution.