There are provided image processing device and method, a printing system, a halftone process determination method, and a program capable of determining a processing rule of an appropriate halftone process appropriate for characteristics of a printing system. An image processing device (20) according to the present invention includes characteristic parameter acquisition means (52) for acquiring characteristic parameters related to characteristics of a printing system, and halftone process generation means (58) for generating halftone processing rules that define the processing contents of two or more kinds of halftone processes of which balances of priority for a plurality of requirements required in the halftone process are different based on the characteristic parameters acquired by the characteristic parameter acquisition means (52).