If you deal with fiction and the like where you basically have just text then I think that's correct: it would be trivial to detect the watermarks in various co

If you deal with fiction and the like where you basically have just text then I think that's correct: it would be trivial to detect the watermarks in various copies by simply comparing them. I was dealing with PDFs containing tables, formulas, illustrations, etc., so a plain-text version would be unusable.