Image Portal at Duke
Duke University's image-database page provides easy links to all the image databases which Duke either subscribes to or recommends. Categories include Art, Photography, History, Science, etc. Also included is copyright and scanning information.
tip: Finding Images in Non-Image Sources
Most online journal indexes have a way to limit to the images of their journal. Often, it's helpful to go to a special subject database, apply your search, and then limit to images/photo/pictures (or whatever they term in).
Example - CINAHL (a nursing studies index)
1. At the blue bar at the top of the CINAHL index has a pulldown "more".
2. Click the "images" option.
3. Perform your search.
4. At the left, check: "Black and White Photograph" (and, if you wish, "Color Photograph")