MLA gives two different ways to cite an images in a presentation depending on how you are using the image in your presentation. The difference depends on whether the image is just for illustration or decoration (a stand along image), or if you're going to refer to this image in your presentation (the image itself is part of the content of your presentation.
Option 1: Image is for Illustration or Decoration (not going to talk directly about the image during your presentation).
In this case, list the entire citation information in the caption of the image. Do not list it on your Works Cited page at the end.
Option 2: Image is Part of the Presentation (going to talk about the image specifically during your presentation)
In this case, you'll still include a caption for the image, but the caption will only include an in-text citation, and the entire citation information will go on the Works Cited page like you with a regular source.
See the two different ways you could use the image below in a presentation, and how the citing would differ.
Option 1: If the image below is on a slide about massage therapists, but you don't directly talk about the image, then you'd include the full citation information in the caption for the image. See below.
Fig. 1: Massage Chair. Massage & Bodywork, vol. 28, no. 3, Dec. 2016, p. 14. Vocational and Career Collection.
Option 2: If you're displaying this image of the massage chair in order to talk about the correct positioning and demonstrate how someone should sit in the chair, meaning that you'll talk about this image and what it shows, then you would include the citation information in your Works Cited, and the caption would just include an in-text citation.
Fig. 1: Correct Positioning in a Massage Chair (Massage Chair).
Massage Chair. Massage & Bodywork, vol. 28, no. 3, Dec. 2016, p. 14. Vocational and Career Collection.