Citing all your sources of information and creative work you use is part of academic integrity. You are giving credit where credit is due.
In academic work, images should be followed by and attribution or in text citation whether that be in a note or caption immediately following the image or at the bottom of a presentation slide. A full citation should be found in your Works Cited or Reference List, though you might separate them out into an Image Credit List, depending on the style of citation you are using.
The 7th edition of the Publication Manual of the American Psychological Association expended their explanations and examples of how to cite multimedia sources including multimedia materials. Examples of reference are found in Chapter 10 of the Manual and the following sections focus on multimedia sources
A related section of the Manual is Chapter 7 which deals with the presentation of tables and figures, so the Manual shows you how images should be incorporated into your work in addition to how they should be cited; see Sample Figure 7.3 for how to include an attribution in the figure note.
Here is an example of how the following photograph (found through Pixabay) should be cited using the APA style.
stokpic. (2015, February 10). Blonde Girl Taking Photo [Photograph]. Pixabay. https://pixabay.com/photos/blonde-girl-taking-photo-629726/
This work (Blonde Girl Taking, by stokpic), identified by Pixabay, is free of known copyright restrictions.
Remember, the library has a copy of the Manual at the Reference Desk if you need to use it.
The 9th edition of the MLA Handbook Appendix 2 has several examples of works-cited-list entries and the examples of citing fine art and still images can be found on pages 331 - 333. The online MLA Style Center also has examples of image citations.
Here is an example of how the following photograph (found through Pixabay) should be cited using the MLA style.
stokpic. Blonde Girl Taking Photo. 10 February 2015. Pixabay. pixabay.com/photos/blonde-girl-taking-photo-629726/
This work (Blonde Girl Taking, by stokpic), identified by Pixabay, is free of known copyright restrictions.
Remember, the library has a copy of the Handbook at the Reference Desk if you need to use it.