How we check the rights

Every image is checked on its own, from its museum's own record, before it enters the treasury.

An image is included when

• its museum releases it under CC0, or marks it Public Domain and it was made before 1931; or
• it was made before 1931 by an artist who died before 1956 (public domain in the United States and in countries that protect a work for the artist's life plus 70 years); or
• it is anonymous and was made before 1900 (book illustrations count here: their illustrators are rarely named).

It is left out when

• it has no provable date, or its latest possible date is 1931 or later;
• its license is non-commercial, no-derivatives or share-alike;
• it is a photograph of people.

Each image page states the reasoning in one sentence and links to the source record. Descriptions are written by Claude from the picture and the record, marked with the model and date, and compared with the museum's record.

Sources: The Metropolitan Museum of Art, the Art Institute of Chicago, the Rijksmuseum, the Smithsonian, Wellcome Collection, Wikimedia Commons and Wikidata, the British Library, the Internet Archive and the Library of Congress.