The standard pdf (non -scan one) should have several ocgs layer, that are text , images and vector objects etc....
The problem is, apart from the Acrobat pre-flight function can separate the pdf with different layer, are there any other tools (preferred java lib / usable on linux) that can achieve the same function?
(Separate the original pdf to text layer and images layer, and save it to two pdf) .
I have tried Itext but it seems not have the mentioned function. Thanks