Ridge Separation & Amplification

Fast Fourier Transform

The Fast Fourier Transform technique can be used to remove regular repetitive background patterns. It can also be used to isolate individual fingerprint ridges and either remove them or increase their intensity. This can only be achieved through using 12 bit images and creating detailed diffraction patterns.

Original image with two overlaid fingerprint impressions

Enhanced image, with the top fingerprint removed and the bottom fingerprint enhanced.

12-bit diffraction

The bright spots are frequency spikes created through repetitive patterns or wavelengths. The spots in one direct represent one set of fingerprint ridges. In the above images, one set of ridges have been removed with ‘spike cut’ while the other have been amplified with ‘spike boost’