E-Commerce Configuration Guide : Site Configuration Settings : Item Settings : ImageField
 
ImageField
Key value:
Field name in the items table – usually item_id
Description:
Used with the image column on the ItemList.aspx page. It is used to specify the field in the item record in the items table to use for the filenames of both the Tn (thumbnail) image and the Lg (large) image.
Example:
ImageField = item_id
See also:
ImageTnPath
ImageLgPath
ImageRel
Imagenodes