Patent ID: 6389163
Filing Date: 2002-05-14
Classification: H04N

Abstract:
A method performed in an digital processor for processing a document image to determine image types present therein, the steps comprising:receiving, from an image source, a document image having a plurality of pixels therein, each pixel represented by a density signal, and storing at least a portion thereof representing a region of the document image in a data buffer; retrieving, from the data buffer, the density signals for the document image; and determining, using template matching filters, image types present in the region of the document image by applying a first stage template matching filter to the density signals for the document image to produce a first filtered output image, said step of applying a first stage template matching filter to the density signals for the document image comprising identifying a window within the document image so as to select a subset of the document image density signals and comparing the density signals in the window to a pattern within the template based filter, the pattern representing a pattern determined to occur in a textual segment of an image wherein a plurality of signals representing a pattern within the template-based filter are stored in each location of a look-up table memory and the step of comparing the density signals in the window to a pattern within the template-based filter comprises storing the subset of document image density signals in a register memory, logically comparing each density signal in the register memory with a uniquely associated signal of the template based filter stored in the look-up table memory location, and outputting a logic signal indicative of the result obtained in the logical comparing step applying a second stage template matching filter to the first filtered output image to produce an error image, and XORing the error image and the first filtered output image to mask from the first filtered output image any density signals from segments of the document image not comprised of text to produce a first output image, wherein the first output image contains only textual segments therein.