Patent ID: 6396576
Filing Date: 2002-05-28
Classification: G01N

Abstract:
A method for determining a cell crossing number of a shadowline between an illuminated region and an adjacent dark region on a linear array having a plurality of photosensitive cells, said method comprising the steps of:A) scanning said array to extract a response signal from each of said plurality of cells, the amplitude of said response signal being determined by the amount of illumination of the corresponding cell by incident light; B) converting said response signals from said scanned array into digital signals containing information as to the amplitudes of said response signals from said array, said digital signals collectively representing an illumination distribution curve with respect to said array; C) establishing a range of cells of said linear scanned array within which said shadowline resides; D) calculating the second derivative of said illumination distribution curve over said range of cells; E) identifying the greatest positive area bounded by said second derivative; F) finding the centroid of said greatest positive area; and G) assigning the cell number coordinate of said centroid to be said cell crossing number.