4. A method according to claim 1 , further comprising: receiving input that selects a predetermined concept which corresponds to a predetermined query model; and ranking the digital images in the collection, with regard to the predetermined query model.
1. A method comprising: receiving an example image for use in querying a collection of digital images; using, by a processing system, a local feature descriptor representing a portion of the contents of a digital image and a global feature descriptor representing substantially all of the contents of the digital image to perform a content-based image comparison of the collection of digital images with the example image, to automatically rank the collection of digital images with respect to similarity to the example image, wherein the global feature descriptor is content based; using a final classifier and multiple different intermediate classifiers to perform the automatic ranking, comprising: generating, by the different intermediate classifiers, intermediate relevance metrics with respect to different modalities; and generating, by the final classifier, results from the intermediate classifiers into a final relevance metric to display images in ranked order; after generating the final relevance metric, receiving input identifying a second example image for use in querying the collection of digital images; automatically determining at least one new intermediate classifier, based at least in part on the example images; automatically determining a new final classifier, based at least in part on the example images; and using the new intermediate classifier and the new final classifier to automatically re-rank the digital images in the collection with respect to similarity to the example images.