1. A method of generating a region-based representation of a document, the method comprising: generating a global compositing sequence based on a predetermined rule, using fill data and at least one compositing operation associated with a plurality of objects of the document, to form an object-based representation of the document; generating the region-based representation of the document based on a further compositing sequence determined for regions formed using the object-based representation; determining whether at least one of said regions satisfies the predetermined rule using a relative arrangement of the objects in the object-based representation, and where said region satisfies the predetermined rule, creating a reference to the global compositing sequence, and where said region does not satisfy the predetermined rule, generating a local compositing sequence using fill data and compositing operations associated with the objects contributing to the region.