In August, the Getty released approximately 4,600 high-resolution images for public use. It is the first release in their Open Content Program and follows a trend in the museum world towards opening up access to digital reproductions of works in the public domain. Patrons can download any of the images in this collection. They are "free to use, modify, and publish for any purpose"*. The Getty does plan to add to this collection over time, after vetting images for copyright and privacy restrictions. A first look at the set reveals photographs by Julia Margaret Cameron and Eugene Atget, paintings by Watkins and Gericault, and more. You can search the set of available images at http://bit.ly/1cv0oiE
Before downloading, The Getty asks for some information about how image will be used. Presumably, providing this feedback will help the Getty to justify the program and to plan additions to the collection. Happy hunting!
* quoted from the announcement for the new program, http://blogs.getty.edu/iris/open-content-an-idea-whose-time-has-come/