Extreme Compression of Fingerprint Images: Squeezing Fingerprints until the Spirals Pop Out

We propose a new mathematical model for human fingerprint images. The model can be summarized by the phrase “fingerprints are holograms”. The model unifies the analysis, compression, classification, matching, and re-synthesis of fingerprints, in a self-consistent formalism. The parsimony of this model is demonstrated by the reconstruction of fingerprint images with extreme compression ratios (typically >200x). At the heart of the method is a recently proposed method for demodulating two-dimensional fringe patterns, such as holograms. Demodulation uses a spiral-phase quadrature transform combined with a two-dimensional orientation estimator that also uses spiral-phase Fourier operators. Finally, the fingerprint decomposition itself achieves compactness by splitting the phase modulation into two unique parts, one of which is a pure spiral-phase function. Spiral-phase inexorably emerges as a central theme of the work.