Object Streams

PDF 1.5 introduced a new mechanism for storing objects to save space: object streams. by default, cpdf will preserve object streams in input files, creating no more. To prevent the retention of existing object streams, use -no-preserve-objstm:

To create new object streams if none exist, or augment the existing ones, use -create-objstm:

To create wholly new object streams, use both options together:

Files written with object streams will be set to PDF 1.5 or higher, unless -keep-version is used (see above).