Patent ID: 6731824
Filing Date: 2004-05-04
Classification: G06K

Abstract:
A spatial filtering method comprising the steps of:(a) acquiring a digital image comprising a two-dimensional array of pixel data from an original image; (b) calculating a first Fourier Transform of the digital image to generate a two-dimensional array of complex data from the equation: F&it;(u,v)=1/N&it;&Sum;x=0N-1&it;â€ƒ&it;&Sum;y=0N-1&it;f&it;(x,y)&it;&ee;-2&it;Ï€j&af;(ux+vy);(c) calculating a power spectrum to provide a real function representing a weighting of each spatial frequency in the two-dimensional array of complex data calculated in step (b) from the equation: P(u,v)=log (1+F(u,v)F*(u,v)); (d) generating a mask for suppressing periodic structures of the original image and undesirable artifacts introduced by the acquiring of the digital image in step (a); (e) dilating the mask generated in step (d) by extending masking spots generated therein to increase suppression of periodic structures of the original image; (f) applying the mask dilated in step (e) to remove the periodic data from the first Fourier transform resulting from step (b) to result in a second set of complex data corresponding to a second Fourier transform; (g) calculating an inverse Fourier transform using the second set of complex data corresponding to the second Fourier transform of the digital image masked in step (f) to obtain a spatially filtered original image from the equation: f&it;(x,y)=1/N&it;&Sum;u=0N-1&it;â€ƒ&it;&Sum;v=0N-1&it;â€ƒ&it;F&it;(u,v)&it;&ee;+2&it;Ï€j&af;(ux+vy);(h) scaling the spatially filtered image to greyscale; and (i) providing a visual representation of the greyscaled image obtained in step (h).