Method and device for transmitting and processing print data used for printer

A method and a device for transmitting print data from a computer to a print control device for controlling a printer, wherein a desired one of attribute data sets which accompany respective image data sets is replaceable by a new image data set in a data transmission mode of the computer, and the attribute data set accompanying the original image data set replaced by the new image data set is suitably changed according to the new image data set. The print data including the new image data set and the changed attribute data set are transmitted to the print control device. The print data may include direct image data such as bit map data, and non-direct image data which include indirect image data such as character data and graphic data, and print control data such as attribute data. When a file name of any direct image data stored in a memory is included in the non-direct image data, the direct image data are retrieved from the memory, and transmitted to the print control device such that the retrieved direct image data and the non-direct image data are not interspersed with each other.