Zotero can capture a snapshot of images from sources, including websites or library databases. However, Zotero does not recognize the item type as an image.
Change the Item Type field to Artwork in order to have the correct field options. The following areas highlighted in red below are usually fields you will need to update for a citation or caption. Chicago Manual of Style guidelines for citing artwork is below.
Chicago Manual of Style, 18th ed. + Images, Artwork:
"Information about paintings, photographs, sculpture, and other works of art is usually presented in the text. If a more formal citation is needed (as in a note or a bibliography—or a separate section of a bibliography devoted to images; see also 13.67), list the name of the artist, a title (in italics) or a description, and a date of creation or completion, followed by information about the medium and the location of the work. To help readers locate the item, a museum accession number may be included; for works consulted online, add a URL."
Citing Sources - Styles
Guides on common styles used in architecture and art.