Google Image Search (also available through the advanced search function from the main Google page) indexes more than 880 million images. For each image a thumbnail is provided, as well as the source and context in which the image appears.

If you can't find the images you need online, a good print source is World Painting Index, located on the 'Ready Reference' shelves in the Art Library. Use it to find a black and white or color image of many major works of art (but not the Ackland works) in other books we have in the Library.