1. a method for enabling searching of portions of objects in images, the method: comprising: programmatically analyzing each image in a collection in order to determine image data that, for individual images in the collection, represents one or more visual characteristics of a portion of an object shown in that image; enabling a user to specify one or more search criteria that includes image data; determining a search result based on one or more images in the collection that show a corresponding object that has a portion that satisfies a threshold, wherein the threshold is defined at least in part by the one or more search criteria.