The MLA Handbook does not have a specific set of rules only for images. As a researcher, you are expected to cite image material based on where you got it, such as the figure in a book or picture on the web. The same basic principles that underlie the entire MLA format will look the same for an image.
Lastname, Firstname (of artist or creator). "Title of Image." Figure number in Title of the Book: Plus a Subtitle. by Firstname Lastname, Publisher, Year of Publication, Page Number.
Medina, John Baptista. "Illustration to Book V, 1688." Figure 5 in Paradise Lost by John Milton, edited by Barbara K. Lewalski, Blackwell, 2007, 121.
Lastname, Firstname (of artist or creator). "Title of Image." Figure number in Title of the Book: Plus a Subtitle. by Firstname Lastname, Publisher, Year of Publication, Page Number.
Blake, William. "The Temptation and Fall of Eve." illustration to "Paradise Lost" by John Milton, 1808, pen and watercolor on paper. Wikimedia Commons, 2006, https://commons.wikimedia.org/wiki/File:William_Blake,_The_Temptation_and_Fall_of_Eve.JPG