If the image is only found on the web, provide the name of the artist, title of the work then follow the citation format for a website. (Remember to delete "http://" from the address, it is not needed and makes the citation easier to read.) If there is no artist information leave it out.
If the the picture was found using Google do NOT cite Google as the publisher, visit the original page and use information from the website that is hosting the picture.
Basic Format:
Last Name, First Name. "Title of the Image." Title of Website, Version (if applicable), Publisher, Publication Date, URL.
Example:
Souza, Pete. "President Obama, Vice President Biden and Members of His National Security Team." PHOTOS: One Photographer's 'Remarkable' Chance To Cover The President, NPR, 26 Oct. 2016, www.npr.org/2016/10/26/499490029/photos-one-photographers-remarkable-chance-to-cover-the-president.
Instagram Post:
(If the work is posted is under a username, use the username for the author. If there is no title for the image provide a short description (some people use the first few words of the image caption.) Since it is technically a description and not the official title it does not get quotes around it.)
Dressed_Podcast. 20,000 followers! Instagram, 8 Jan. 2019, www.instagram.com/p/BsYKpQkADCr/.
Artwork from Museum Website:
van Gogh, Vincent. "Self-Portrait with a Straw Hat (obverse: The Potato Peeler)." The Metropolitan Museum of Art, 1887, www.metmuseum.org/art/collection/search/436532. Accessed 3 Jan 2019.
Although this image is almost identical to the image from the Metropolitan Museum of Art's website it is cited in the style of an article from a database. Also note that ARTSTOR's data is slightly different from the Metropolitan Museum of Art's ("verso" instead of "obverse"). Whenever possible try to copy citation information word for word.
van Gogh, Vincent. Self-portrait with a Straw Hat (verso: The Potato Peeler). 1887. Artstor, libproxy.fitsuny.edu:2717/asset/MMA_IAP_1039651908
from https://style.mla.org/citing-online-images/
Original Artwork in Museum:When citing the original artwork (like a painting you saw in a museum) include the city the museum is located in:
van Gogh, Vincent. Self-Portrait with a Straw Hat (obverse: The Potato Peeler). 1887, The Metropolitan Museum of Art, New York City.
Here is an example of how to cite the same painting but from a picture in a book. (Note that the museum description and book description differ slightly):
van Gogh, Vincent. Self-Portrait, The Metropolitan Museum of Art, New York City. Van Gogh in Arles, by Ronald Pickvance, Harry N. Abrams, 1984, p. 34.
For an image you took yourself you should cite yourself as the author, create a short description for the title of the photo and include the date the photo was taken.
Smith, Jane. Photograph of Self in Front of Rothko Painting. 25 Sept. 2015. Author's personal collection.