Getty Open Content in the Getty Art Collection. Google Search results for “without charge” suggests there are currently around 1,700 such images in the Getty Open Content public domain programme. Sharp 20mb+ hi-res versions are available, though a simple anonymous form on which the user tells Getty the intended use.

The Getty has an Advanced Search panel which can limit the search results to Getty Open Content. A test for “rabbit” unearthed nine items, but failed to unearth a delightful rabbit in a 13th century illuminated manuscript.

The manuscript rabbit was however found via a straightforward keyword search in DuckDuckGo’s Image Search… “without charge” rabbit

However I should note that DuckDuckGo Image Search also failed to find the other nine “rabbit” results.

Further perusal of the 17Mb source picture for the single-rabbit image found by DuckDuckGo, revealed there were actually two such rabbits on the manuscript page…

Thus a combination of a Getty Advanced Search and DuckDuckGo Image Search seems useful for public domain picture researchers.