Yes, you must cite any image you use. Yes, that includes Creative Commons.
Manet, Edoaurd. The Dead Toreador. 1864. The National Gallery of Art , Washington D.C. Widener Collection. Web. 10 Dec, 2015.
Most databases offer images. Cite image as a short work from a website.
Creative Commons is a source for images. The images included in Creative Commons have a modified copyright which means the copyright owners have voluntarily relinquished some of their rights as a copyright owner.
These copyright modifications are significant for people who need images for commercial use. When you see "no attribution required" that is for when an image is used for commercial purposes. The copyright owner is telling people that you can use the image without having to contact him first to ask permission, and that you do not have to give him credit for the image.
PLEASE BE AWARE: The rules of good scholarship always apply when using someone else's work for academic purposes.
If you have a blog, website, or business you may use a "no attribution required" image freely.
If you are doing a project for school, you must cite it.
Citing Images from the Internet
Example: Image from a website:
"Spears." Internet History Sourcebook, Fordham University. n.d. Web. 26 Jan. 2016.
<http://legacy.fordham.edu/halsall/medny/travis2.asp>.
Example: Image from a database:
"An Illustration of Nobles Hunting a Stag." All Things Chaucer: An Encyclopedia of Chaucer's World, CredoReference. n.d.
Web. 29 Jan. 2016. <paste PERMALINK here if required by your teacher>.
Example: Image from an online diagram:
Emphysema is a Lung Disease. Diagram. 2008. National Institutes of Health. Web. 14 Sept. 2009.
<http://www.nlm.nih.gov/medlineplus/ ency/imagepages/17055.htm>.
Example: Image from a museum website:
Da Vinci, Leonardo. Mona Lisa. 1519. Louvre, Paris. Masterpieces of the Louvre. Web. 29 July 2009.
<http://www.louvre.fr/llv/commun/home>.