If you have an image and you are either trying to identify it or you are trying to figure out who owns copyright for it (which may or may not be successful), try:
TinEye (http://labs.tineye.com) This is the biggest reverse search engine, searching 1.5 billion images. TinEye will provide information on other versions of the image you upload that are available and will attempt to provide the source for these images.
Google Images (http://images.google.com/imghp?hl=en&tab=wi) Upload your mystery image by clicking on the little camera on the right side of the search box.
Multi-source search engines:
Dogpile (click on Images Tab) (http://www.dogpile.com/dogpile_other/ws/index) (Searches Google, Bing, and Yahoo at once)
Single search engines:
Google (www.google.com) (Search term(s) then click on Images tab. Sometimes gives source, if you click on individual image)
Wikimedia Commons (https://commons.wikimedia.org/wiki/Main_Page) Searches over 25 million open source images.
Flickr: Creative Commons (http://www.flickr.com/creativecommons) (Copyright holder offers some permissions to use)
Flickr: The Commons (http://www.flickr.com/commons) (Public domain photographs offered by museums worldwide)
Bing (http://www.bing.com/images?FORM=Z9FD) (Microsoft’s search engine, click on Images tab)
Yahoo Image Search (http://images.search.yahoo.com/)
Museums, Cultural and Educational Institutions: If you know where item or items you seek might be located, look for the institution name in a search engine, and get into their website. More and more educational and cultural institutions are adding their vast collections of images online.
For example:
Aga Kahn Visual Archive
Metropolitan Museum of Art
Eastman Museum (Rochester)
Rijksmuseum (Amsterdam)
Dumbarton Oaks Research Library and Collection
Commercial Sites (For purchasing images):
Bridgeman Images Offers more than 400,000 high quality images of art available for purchase from private collections, museums, galleries, historical societies and artists around the world.
Getty Images (http://www.gettyimages.com/): Stock photo company with over 80 million still images in their collection including Corbis images and also see Getty IStock photos (https://www.istockphoto.com/)
Magnum Photos (http://store.magnumphotos.com/collections/square-prints-sale)
Mary Evans Picture Library (http://www.maryevans.com/): Historical images from the United Kingdom.
Motion Picture and Television Photo Archive (http://www.mptvimages.com/): Specializes in entertainment photography, with photos ranging from Hollywood’s Golden Age up to modern productions
Scholars Resource (http://www.scholarsresource.com/): Incorporates image collections from Saskia, Davis, Hartill, Archivision and Bridgeman.
Time Life Pictures (http://timelifepictures.com/): Within Getty Images, this is from Time’s collection of magazines, such as Time, Life, People, and Sports Illustrated.