Dave - Assuming that you have either a) written the book, or b) acquired publishing rights to the book, or c) the book is over 75 years old (or fits the criteria found inhttp://www.cohums.ohio-state.edu/english/organizations/ijjf/chart.htm)...
Most folks buy a scanner with several applications bundled with it: among them, an OCR ( Optical Character Recognition) app.
These programs take your scanned images of text and convert them to editable, useful text. If your source pages are clean and clear, you can get some good results. Otherwise, you get a lot of errors, and a lot of editing and cleanup.
If the book is bound, you may have to disassemble it to get a good read: the inner binding may keep your scanner from seeing the characters near the book binding.
Hope it's not 75+ years old...
best -
roger
