The analysis refers to “Orphan Works” but really only counts Orphan Books.
There are many more types of copyrighted “works” whose copyright holder is unknown, and which would be subject to any kind of Orphan Works legislation like S2913, the unsuccessful 2008 Orphan Works Act.
Not all are included of course in the GBS, but some maps and some illustrations are as inserts.
The true count of Orphan Works is much much larger when you count photographs, illustrations, fonts, textile designs, sound recordings etc etc.
Furthermore GBS only counts works registered with the Copyright Office. Many other copyrighted works have not been registered. Indeed, for visual works, even finding out if a work has or has not been registered, perhaps as part of a group registration, is nearly impossible
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Several photographic associations including ASMP, NANPA have objected to the proposed settlement in part because the negotiations did not include visual arts representatives.
“The vast majority of photographers and graphic artists, whose works have been and continue to be digitized by Google without authorization, and who have been members of the plaintiffs’ class since June 2006, would neither receive compensation for past infringement nor any benefit going forward. .. The visual arts community has copyright interests at stake that are just as important as the copyright interests of authors and publishers that this Proposed Settlement is designed to protect.” - Vic Perlman, ASMP