If you add images to your work, you need to make sure you are not breaking copyright law. Images that are not in the public domain are protected by copyright laws. Just because an image is online does not mean it's in the public domain. Images can still be protected by copyright, even if a creator or © is not clearly stated. In general, images used in a classroom presentation, for a scholarly lecture, or in an unpublished assigned paper, fall under the concept of or the Teach Act For a description of how this applies to instructors and to students, check out Colgate University's Digital Images and Copyright page.
The database has a citation tool that will generate a citation for the image in the style format of your choice (MLA, APA, Chicago).
Iiwi. [Photograph]. Retrieved from Encyclopædia Britannica ImageQuest.
APA citation example