Printing which satisfies an index of performance of a printing apparatus may be unfeasible depending on the sizes of image information and attribute information which a print data processing apparatus transfers to the printing apparatus, a network band, or the index of performance of the printing apparatus. The print data processing apparatus converts a difficult-to-compress attribute contained in the attribute information into an easy-to-compress attribute, and transfers the converted attribute information to the printing apparatus. The printing apparatus extracts the attribute converted by the print data processing apparatus, by using the image information.