1. In a printing system comprising a coprocessor adapted to translate image data according to an interpretation code, a memory for storing a plurality of interpretation codes and image data, and a guesser for determining an image format of a sample of image data, a method of combining data sets of heterogeneous image formats comprising the steps of: translating a first image data set of one image format including "end of job" data; in response to translating the "end of job" data in the first image data set, transferring the first image data set in a final image format to the memory, and transferring a second image data set of one image format from the memory to the coprocessor; determining the image format of the second image data set; loading to the coprocessor an interpretation code for translating the second image data set; translating the second image data set including "end of job" data; and in response to translating the "end of job" data in the second image data set, transferring the second image data set in a final image format to the memory so that the translated second image data set becomes continuous with the translated first image data set in the memory.