A spatial filtering method providing quick detection and visualization of
irregularities of SEM images of components such as integrated circuits
includes the steps of: (a) acquiring a digital image as a two-dimensional
array of pixel data from an original image; (b) calculating a first
Fourier transform to generate a two-dimensional array of complex data; (c)
calculating a power spectrum to provide a real function representing a
weighting of each spatial frequency in the original image; (d) generating
a mask for suppressing regular 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 the suppression of regular structures
of the original image; (f) applying the mask dilated in step (e) to the
data from the first Fourier transform for removing periodic data to result
in a second Fourier transform; (g) calculating an inverse Fourier
transform of the data of the second Fourier transform to obtain a
spatially filtered image; (h) scaling the spatially filtered image to
greyscale; and (i) providing a visual representation of the greyscaled
image obtained in step (h).
