[Vague Rant]

I feel like you're understating the proliferation of text PDFs vs. pure image series. I'd say the vast majority of PDFs are text rather than images. Of course, the PDF format allows the content creator to choose whether the text can be selected, etc., so in practical terms it might seem like it's just an image, but I believe there's ways of getting around PDF rights settings and copying the text from a restricted document. However, I haven't had occasion to do this, so I'm not at all sure how it's done. Even image-based PDFs like comics can use formatted text for captions and such, though copying the text alone from a comic would rather defeat the purpose.

EDIT: Just for the hell of it, I found myself a PDF password cracking app (links delted by moderator) and cracked the password for this example file: (link deleted to secured version). It only took a couple of minutes or so--I was expecting longer so I didn't actually watch the window to get an exact reading. That said, the password on this example file is "test", I'm sure a more secure password would take longer. Then again, I ran the cracker on a netbook, so it should be significantly faster on any modern desktop. Before anyone asks, PDF cracking is in no way illegal; I suspect sharing cracked PDFs without the author's permission would be, though.