1. A computer-implemented method comprising: receiving a plurality of reference images; calculating by a computer image parameters for each reference image wherein the image parameters characterize color, texture and shape features that are common to the reference image and at least one other reference image; combining by the computer the calculated image parameters to generate a composite reference image; and comparing by the computer the composite reference image to images in a collection in order to identify one or more of the images having features described by the composite reference image.