Owner/author. (publish date or n.d.) Title of image in italics. Retrieved from URL (no period at the end)
Don't know date? Use n.d.Don't know title of image? Put a descriptive title in brackets [descriptive title].
See examples from the University of Maryland guide.
Kitchens, R. (2013). Chart for APA Citations of Images on the Web Retrieved from http://libguides.scf.edu/content.php?pid=107184&sid=1354168
According to the OWL at Purdue, "you do not need documentation or credit...when you use your own artwork, digital photographs, video, audio, etc." (OWL, 2013). For more detailed information see:
Citing Unpublished Photographs Taken by Another Person
For this you can cite the photo the way you would a published one, without the URL.
Owner/author. (publish date or n.d.) Title of image in italics. [photograph].
(include URL if item is public and published from a blog, Flickr or Facebook)
You also want to include a permission or copyright statement that credits the photographer (copyright permission of Susan Ariew).
Be sure to include a caption for all photos, giving them context with the rest of your document.
Citing an unpublished photograph using APA style when one is not the creator of the photograph and the creator's name is known.