1. A method of delivering an image, comprising: for each image in a collection of images: determining by a processor a variation of quality signature (VoQS) of the image, wherein the VoQS of the image comprises a plurality of element signatures, comprising: generating a plurality of distorted versions of the image, wherein each distorted version of the image is formed by applying a different level of distortion to the image, and wherein the different levels of distortion are applied using a single compression algorithm; and determining the plurality of element signatures, wherein each element signature corresponds to one of the plurality of distorted versions of the image, and wherein each element signature measures a degree of similarity between the image and the corresponding distorted version of the image; categorizing by the processor the collection of images into a plurality of clusters of images, wherein images having similar VoQSs are categorized together; for each cluster of images: selecting an exemplar image that best represents the cluster of images; and determining an image quality threshold for delivering the exemplar image; receiving a request for a new image, wherein the new image is not an image in the collection of images; determining by the processor a variation of quality signature (VoQS) of the requested new image determining a nearest exemplar image to the requested new image by comparing the VoQS of the requested new image with the VoQS of the exemplar image of each of the plurality of clusters of images; and delivering a distorted version of the requested new image based on the image quality threshold for delivering the nearest exemplar image.