1. An image processing system comprising: an image processing computer coupled to a wide area network and to an image source computer; and one or more processors configured to perform actions, including to: generate an image distance metric from a set of images, wherein the image distance metric indicates image feature weights corresponding to image features associated with the set of images; retrieve an input image; extract a first set of input image features from the input image, wherein the first set of input image features corresponds to the image distance metric; extract a set of image features from individual ones of images in the set of images, wherein set of image features corresponds to the image distance metric; using the image distance metric, compute one or more image feature distances between the first set of input image features and individual ones of the set of image features; select, from the set of images, a subset of images based at least in part on image feature distances, the subset of images corresponding to a set of scene types; determine a scene type from the set of scene types; and assign the scene type to the input image.