Google Art Project images of two dimensional art in the public domain are available on Wikimedia Commons:
The collection consists of 1,061 high-resolution images by 486 different artists from galleries including the Tate Gallery in London, the Metropolitan Museum of Art in New York City and the Uffizi in Florence.
Some of the images are extremely high resolution, ideal for close study and remixing. The Seurat painting above is available as a 30,000 × 19,970 pixel, 218.33 MB JPEG image for example. Larger images are also available tiled, idead for Digital Humanities analysis or just using a detail as your desktop wallpaper.