The following link takes you to a site with great examples of how to cite images using Chicago Manual of style in your papers. You can also consult the Chicago Manual in sections 12.31 - 12.51 for directions on how to write captions and credit lines.
JSTOR is now more than just journals. Via this database you have access to thousands of images, audio, and video (in relation to books and periodicals) related to a variety of disciplines in addition to art, art history, and classics. This is also the place to gain access to our licensed images from Archivision, Inter-American Institute, Scholars' Resource as well as locally produced images for the Teaching Collection. You can also access licensed films in on JSTOR.
NOTE: "Users can create a registered user account when accessing JSTOR from a valid IP address (either on campus or through a proxy server - VPN). Each registered user account allows for one year of Remote Access during which it may be used to access JSTOR from any computer. Each time a user logs in to his or her account from an authenticated IP address, the one-year period is reset."