I don’t know how you’re going to get a hold of the text from the images. But I do know that if you’re trying to create a book file, PDFs are not the answer. EPUBs are far better, and an open standard. I recommend creating them using the Calibre EPUB editor.

The reason EPUBs are better is because they were designed specifically for books. They’re reflowable (meaning the pages aren’t fixed-size, and therefore can be read on devices of all sizes), whereas PDFs have fixed content, and are very difficult to read on small things like phones and e-readers, requiring zooming just to see the text. Also, EPUBs aren’t very difficult to create. You just have to know how XML works. It’s basically just a zipped directory containing markup files.