Registration and classification of non-textual information, such as digital images and video is described. Image searching and comparison of the images is also described. The digital images are indexed (i.e., each image is assigned a unique numerical parameter and/or a plurality of numerical parameters). The resulting index files are stored in a database that can be quickly searched because the index files are universal numerical files that are significantly smaller in size than their source images. Image search queries are also indexed to generate an index file, which is then compared with the stored index files. A similarity score is also calculated to rank the similar images based on the index file-to-index file comparison.