Application of Hyperspectral Imaging to Forensic Document Examination Problems

Imaging spectroscopy is a powerful tool used extensively in many different remote-sensing applications. The parallel to applications in forensic document examination is exact, but the potential of this method has not been fully explored. A customized imaging system based on electronically tunable filters was used to generate hyperspectral image data from ink samples known to be difficult to differentiate using other spectral methods. The potential of hyperspectral imaging (HSI) as a tool for forensic document problems was evaluated specifically for ink differentiations and the decipherment of obliterations on questioned documents. In this study, various HSI methods were used to show differences between test inks. The most effective results were seen in plots of spectra response, while other methods (such as pseudo-color images of select bands) proved to be ineffective. Select results were also compared to those obtained using a VSC-2000 and found to be as good or better. The basis for a fully automated HSI analysis system was developed.