Image Search Engines offer access to images stored on other sites on the free web. Digital Image Collections offer access to specific content associated with that collection.
is a "nonprofit digital library of more than one million images in the arts, architecture, humanities, and social sciences with a suite of software tools to view, present, and manage images for research and pedagogical purposes. The OWHL makes a subscription to this rich resource available to current students, faculty, and staff of the Academy.
Creative Commons on flickr. All of these images (more than 12 million) are free to use as long as you attribute the photographer.
Institute of Museum and Library Services. Adding "image" to the keyword search will retrieve digital images and their corresponding metadata.
Library of Congress American History and Culture Collections (American Memory) This rich collection may be searched or browsed by more than 100 subjects, time period, and location.
Library of Congress International Collections. Contains international visual images from the Library of Congress, as well as providing a gateway to the image collections of national libraries in other countries.
NYPL Digital Gallery (New York Public Library)
New York Public Library Picture Collection (by subject)
Photomuse. Collections of the George Eastman House International Museum of Photography
Selected University Digital Image Collections
Google Image Search is the largest and most popular image search engine. It offers both simple and advanced searching, including the use of Boolean and the ability to limit your results to news content.
Exalead is not as well known as Google, but gives excellent results for image searching. It has a braod scope, and excellent search options, presentation, and performance. It features face recognition technology.
This "meta-search" engine offers a quick way to search 22 separate image search engines. While you give up the functionality available in the native engines, you can use a meta-search to determine which search engines might be useful for your project.