20. The method according to claim 19 , wherein the first set of intermediate representations is selected when a number of generated intermediate representations reaches a predetermined number.
19. A computer-implemented method for merging intermediate representations of a page to be rendered, the method comprising: receiving, by an image rendering device, a page description language representation of the page, the page description language representation having a plurality of sequential graphic objects ordered by drawing order; forming a plurality of groups of sequentially adjacent graphic objects of the plurality of sequential objects, each group being associated with a z-order according to the drawing order; generating an intermediate representation from each of the groups, wherein at least two of the intermediate representations are generated concurrently; creating a data structure comprising records each corresponding to one of the intermediate representations, a z-order for each of the records, and a status of generating the corresponding intermediate representation; determining whether the generated intermediate representations form a first set of intermediate representations adjacent in the z-order using the z-order and status of the records in the created data structure; merging, by the image rendering device, the first set of consecutive z-order intermediate representations in accordance with the associated z-orders to form a merged intermediate representation; and determining, using the created data structure, whether the merged intermediate representation and an intermediate representation preceding the merged intermediate representation in the z-order form a second set of intermediate representations adjacent in the z-order; and merging the second set of consecutive z-order intermediate representations to render the page.