Images include photographs, illustrations, and other artwork. Beyond artworks found in museums (or images of those artworks), these materials can also be photographs, illustrations, or comics found in other environments, like websites, magazines, or books. 

MLA:

Child, Paul. Julia Child at the White House. 1967. Schlesinger Library on the History of Women in America, Radcliffe Institute, https://id.lib.harvard.edu/images/olvwork539731/catalog.

APA:

Child, Paul. (1967). Julia Child at the White House [Photograph]. Schlesinger Library on the History of Women in America, Radcliffe Institute, https://id.lib.harvard.edu/images/olvwork539731/catalog.

Chicago Notes:

Child, Paul. Julia Child at the White House. 1967. Photograph, 10 x 8 in. (25.4 x 20.32 cm). Schlesinger Library on the History of Women in America, Radcliffe Institute,  Cambridge, Mass. https://id.lib.harvard.edu/images/olvwork539731/urn-3:RAD.SCHL:4510469/catalog.

Chicago Author-Date: 

Child, Paul. 1967. Julia Child at the White House. Photograph, 10 x 8 in. (25.4 x 20.32 cm). Schlesinger Library on the History of Women in America, Radcliffe Institute,  Cambridge, Mass. https://id.lib.harvard.edu/images/olvwork539731/urn-3:RAD.SCHL:4510469/catalog.

The elements of an image that may be needed to create a citation vary by style guide and can be extensive. 

• Creator
• Image title
• Date of composition
• Medium (e.g. painting, photograph)
• Dimensions (metric and imperial)
• Institution name and location
• If found in a book or on a website:
  • Source title
  • Source author
  • Source publisher
  • Page number or URL