Images, audio, and video sources are more difficult to cite because they tend to be held under a higher standard in copyright law. One thing to be aware of is even if an image is cited, that doesn't necessarily mean you had permission to use it in the first place. You should stick to using images that either you created or belong to the creative commons. A good site for finding creative commons images is https://www.flickr.com
When you are citing an image in APA format (which is generally the format you should use in science based classes), you want to follow this template:
Last Name, First initial. (Role of creater, such as painter, sculptor, digital artist, ect). (year of creation). Title of image or if no title found a small description of image. [type of work, such as painting]. Retrieved from URL
If I wanted to cite the Funk Mountain album art found here, I would use the following:
jouste. (Digital Artist). (2018). Funk Mountain [Digital image]. Retrieved from https://morgandavidking.com/lore/funk-mountain/
Sometimes, you can't find all the information you need. In these cases, you simply make do with what you can. If the artist has a screen name but no real name listed, use that, maintaining the original capitalization of the name. Please note that just adding a link to the Google image search result DOES NOT COUNT AS A CITATION as Google is NOT the artist that made the image.
You may find generators like this one helpful. If the author uses a display name, enter it in last name.