1. A method for determining the type of an electronically stored image of a document, the image comprising a plurality of pixels which pixels may take one of a plurality of values, the method comprising the steps of: projecting image data from said document horizontally on a vertical axis based on a super linear function where the sum of squares of lengths of sequences of the number of contiguous pixels having the same value are determined along straight lines in the image data in a predetermined direction; computing a signature for the image data by detecting the position of N highest peaks within said image data; comparing said computed signature with a plurality of pre-stored master signatures, each master signature having a document type associated therewith, to determine the master signature which had the highest similarity with said computed signature, the type of the document being thereby determined to be the same as the document type associated with the master signature having the highest similarity.