Frequency Filtering of Fingerprints to Remove Noisy Backgrounds
The Fourier transformation (FT) of an image allows selective filtering of frequencies associated with noisy backgrounds; the end result is a cleaner filtered image.
The image shown here illustrates the utility of the filtering process, beginning with a photograph of a fingerprint (topmost image, Ref. Fikes, T. (2011)), the FT power spectrum and four filters that remove frequencies associated with the interfering vertical lines (center image), followed by the inverse transformation (bottom image), or a cleaned-up version of the original fingerprint. Elliptical regions highlight frequences that have been removed by the filtering process.