Check out this 3D image of a Japanese folding screen (Edo period, mid 17th c. by Master of I-nen Seal (1600-1630), F1962.30) from the Sackler Museum and then look at it through the collections image viewer: https://asia.si.edu/object/F1962.30/#txtMetaData
Hooray for 3D imaging and Sketchfab!
There is a new absolutely gorgeous online collection for the National Gallery of Denmark (Statens Museum for Kunst): https://open.smk.dk/
Learn more about the process of putting their collections online here.
Read this interesting article: The Great Wave: what Hokusai’s masterpiece tells us about museums, copyright and online collections today. By Douglas McCarthy of Europeana.