The Chicago Manual of Style, like most methods of documentation, requires the researcher to be very detailed and precise. Even with pictures or images, those same strict rules apply. Now remember: Chicago Style can be a little different, because in your research writing/report, the actual citations are shown in the footnotes/endnotes and the bibliography.
I am going to show you a couple of example formats, because I did not know the source of the picture, whether you found it in a book, web, or personal photograph--it does matter, when it comes down to documenting correctly.
Citation for actual artwork:
Malone, Kate. Queen Pineapple, 1994, Stoneware sculpture, 97 cm. Manchester Art Gallery.
(Don't forget to tab over on the second line of your citation. The document box doesnotsupport this feature.)
Citation for Works of Art found online:
Malone, Kate. Queen Pineapple, 1994. Manchester Art Gallery. http://machestergalleries.org/ (accessed April 24, 2012).
Image of Artwork from an Online Database:
Malone, Kate. Queen Pineapple, 1994. Library of Congress Prints and Photographs Online Catalog, http://www.loc.gov/pictures/item/23543556/ (accessed April 24, 2012).
(**don't forget to wrap text and tab on second, subsequent lines..**)
I hope these are helpful to you in your research project!