Project Gutenberg has over 50,000 eBooks in its collection. This is far
fewer than Google Books, or The Internet Archive, or other large-scale
digitization projects of historical items. An important distinction
is that Project Gutenberg engages in the proofreading, formatting,
markup/encoding, and other activities described above. Those other very
large projects are primarily devoted to scanning, and then provide raw
OCR output with a few automatically generated formats.
Such items are only partial eBooks — really, they are pictures (scans)
of books, with some additional automated features. These are valuable,
but do not provide the reading experience or quality of presentation
that Project Gutenberg strives for. Using current technology, it takes
human intellect and effort to convert a picture of a book to a true,
functional, eBook.