1. A method within digital hardware software or firmware or combinations thereof, for efficient image-based indexing and classification of documents in digital image databases, the method comprising: selecting a representative image; quantifying features of the representative image; using a training set of similar type images to automatically establish a hierarchy of classifier parameters to be used as feature comparators; quantifying features of images in the database documents; and sorting the document image features using the established classifier parameters in cascaded comparisons to reduce a set of document images to an operably small set of candidate images for comparing to the representative image on a feature by feature basis.