Disclosed is an image processing apparatus to generate printing data, comprising: a storage section to store the image data and reference data; a printing data generating section to generate the printing data based on the image data and the reference data; and a control section to output an address of the image data and that of the reference data to the printing data generating section, wherein the printing data generating section obtains the data based on the addresses thereof, and stores them in an internal storage section of the printing data generating section, and the control section outputs both of the addresses thereof when storage content stored in the internal storage section does not include the reference data obtained based on the address thereof, and only outputs the address of the image data when the storage content already includes the reference data obtained based on the address thereof.