A novel
data processing apparatus makes adding, deleting, and changing of modification rules easy. This
data processing apparatus includes an output destination type determining unit 302 that determines type of output destination determined by an output destination determining unit using categorizing information, modification
processing units 306a-306c that execute modifying processes different from each other on content of image data, a Plug-in Factory 304 that determines the modifying process by referring to the determined type and content of modifying process set for each categorized type and generates modification
processing units 306a-306c that execute the determined modifying processes, and a print commanding unit that requests modification
processing units 306a-306c to execute the modifying process, generates output data from the modified image data, and sends the output data to the determined output destination. The content of the categorizing information and modifying process can be customized, and modification processing units can be added or deleted.