As a person who enjoys the digitized reproductions, on the web, of old illustrations, I found this interesting reading:
Gutenberg: No Sweat of the Brow Copyright
From Project Gutenberg, the first producer of free electronic books (ebooks).
Work performed on a public domain item, known as sweat of the brow, does not result in a new copyright. This is the judgment of Project Gutenberg’s copyright lawyers, and is founded in a study of case law in the United States. This is founded in the notion of authorship, which is a prerequisite for a new copyright. Non-authorship activities do not create a new copyright.
Some organizations erroneously claim a new copyright when they add value to a public domain item, such as to an old printed book. But despite the difficulty of the work involved, none of these activities result in new copyright protection when performed on a public domain item:
▪ scanning and optical character recognition (OCR)
▪ proofreading and OCR error correction
▪ fixing spelling and typography, including substantial updates to spelling such as changing from American to British English
▪ adding markup (HTML, XML, TeX, etc.)
▪ digitizing, cropping, color-adjusting or other modifications to images
▪ addition of trivial new content, such as images to indicate page breaks in an HTML file, or pictures of gothic letters for the first letter in a chapter, or adding or removing a few words per chapter
▪ substantial reorganization, such as moving footnotes to end-notes, or changing the locations of pictures within the text
▪ recoding to new character sets, such as Unicode, or new formats, such as PDF
There is some value-added content that DOES get a new copyright, but only for the actual new work (that is, it may be possible to remove the new copyrighted content to go back to a public domain document):
▪ translation into another human language
▪ creating a new compilation of existing materials (though the individual items compiled retain their public domain status)
▪ creating new original art work
▪ creating an original derivative work, such as an audio performance, a new chapter, or a set of favorite quotations
▪ adding a new introduction or critical essay
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