Effects of Decomposition Levels and Quality Layers with JPEG 2000 Compression of 1000 ppi Fingerprint Images

Abstract

As part of NIST’s investigative efforts to support development of the FBI Next Generation Identification (NGI) systems, this investigation evaluates effects on image fidelity of wavelet transform decomposition and quality layer options for JPEG 2000 compression of 1000 ppi fingerprint images. First, a suite of 1000 ppi fingerprints are subjected to encoding specifying from three to eight levels of DWT decomposition. Decoded images are compared to non-compressed source images and fidelity loss is evaluated by certified latent fingerprint examiners as well as by several automated computational fidelity metrics. Fidelity losses among the six decomposition level options result in no statistically significant differences among assessments of image degradation by trained fingerprint examiners. Computational metrics find statistically significant fidelity differences, with lowest error for five and six DWT decompositions. In a second experiment JPEG 2000 encoding is applied using from one to nine quality layers. Computational fidelity metrics find statistically significant increase in error with the addition of even a single additional compression rate beyond using only a single target compression ratio of 10:1. Moreover, fidelity loss increases with the addition of each additional quality layer. Hence, while the provision of JPEG 2000 for multiple compression rates within a single code stream adds to the flexibility of this CODEC, the additional flexibility is not without measurable loss in fidelity. However, maximum error rates measured among the various quality layer configurations are found to be below that detectable by certified fingerprint examiners. Hence, judicious use of quality layers should be acceptable for JPEG 2000 compression of 1000 ppi fingerprints.