Digital Collections: National Library of Medicine's Free Onine Archive

"Digital Collections is the National Library of Medicine's free online archive of biomedical books and videos. All of the content in Digital Collections is freely available worldwide and, unless otherwise indicated, in the public domain. Digital Collections provides unique access to NLM's rich, historical resources.

About the Collections
Texts
The majority of the texts within Digital Collections were digitized at NLM using a Kirtas KABIS III scanning system, which produces several files per page and per book.  After cropping, deskewing and reviewing the source images, additional image derivatives and metadata are then created using NLM-defined scripts.   A smaller number of texts were digitized from original or microfilm by a vendor offsite.
The texts comprising the Medicine in the Americas collection were digitized for a multi-institutional digital library project, the Medical Heritage Library, which uses Internet Archive to host its collection.  Therefore NLM routinely deposits copies of its digitized books to Internet Archive.  More information on the Medical Heritage Library can be found here.

Films
The films available in Digital Collections come from NLM's reel and videotape holdings of government and military-created productions.  The source material was digitized to MPEG2 format, which served as the digital master for the range of video derivatives offered by the repository. Each film was manually transcribed, with time-coded captions then created using WGBH's Magpie application."
Ernster, the Virtual Library Cat