Need an image that is not under copyright? There are some little known free high quality and high resolution collections. The Open Education Database (OEDb) iLibrarian blog has a list of collections with brief descriptions of each collection.
The Image Collections include:
The Metropolitan Museum of Art
Getty Open Content Images
LIFE Photo Archive
NOAA Photo Library
And more. Even if you do not need an image, it is a pleasure to browse the collections and view some extraordinary photos.
Ernster, the Virtual Library Cat