When you use an image in a paper or presentation, you must provide a citation. The exact citation format will depend on your bibliographic style (MLA, Chicago, Turabian, APA, etc.).
Most citations require the following information:
Name of the artist/creator
Title of the work
Date the work was created
Repository, museum, or owner
City or Country of origin
Dimensions of the work
Material or medium such as oil on canvas, marble, found objects
If you found the image in a book you will need the author, title, publisher information, date, and page, figure or plate number of the reproduction
If you found the image online you will need an access date, the web site address (URL) and in some cases an image ID number. Remember that an image displayed on a website does not necessarily belong to that website's author!
For examples of how to cite images, see the following guides: