@Edent Hi! The watermarks are everything from /Artifact (this is actually the first argument to the BMC operator) to EMC. They don't have a length, but once you remove them you have to fix up the /Length on the enclosing content stream. However! Since you decompressed the stream, you can just set the /Length to 0, and any PDF viewer can figure it out.
David Huggins-Daines
@dhd6@jasette.facil.services