Detection of latent fingerprints on papers

Abstract

Fast and high resolution detection of latent fingerprints plays an important role in criminal investigation and court science litigation. Researches show that fingerprint has a main absorption peak in the short-wave ultraviolet region, and the corresponding fluorescence peak appears in the long-wave ultraviolet region. In the paper, the scanning module is adopted to realize the shift of 266nm laser spot on the surface of paper, meanwhile, the fingerprint fluorescence emitting from the scanning area is collected. The experimental parameters are optimized according to the contrast of fingerprint image. Two modes of rough detection and fine detection are used to realize fast and high resolution fingerprints detection. According to the natural width of two adjacent ridges of fingerprint(0.2-0.7mm), the optimum detection resolution of rough and fine detection mode is studied. In this paper, the rough detection resolution is 0.2mm, and the fine detection resolution is 0.06mm. Histogram stretching and exponential enlargement are used to enhance fingerprint image contrast. Image filtering and binarizing are carried out to show fingerprint image stripes. By above method, characteristics in latent fingerprints can be detected, and fast and high resolution detection of latent fingerprints is realized, and the fingerprint image features are accurate, high contrast and rich in details. It has important applications in criminal investigation, forensic science and other fields.