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Hyperspectrum Imaging and Processing in Forensic Document Analysis.

Hyper-spectrum image is 4D data array that consist of optical spectra for each point of the image. Technically the Hyperspectrum can be measured either by scanning each point of an object with spectrometer or by recording series of the images taken at narrow spectral band. In case of forensic document examination the hyper-spectrum is reflection (or/and luminescence) spectral data set measured at each point of a questioned document. The hyperspectrum processed with our advanced software reveals much more information about the image as compared to visual spectral comparison (VSC) method or single point spectrum measurement. For example, if one is to compare (impartially detect) different inks in one document, then processing is done such as to reveal unique spectral signatures in each point of the document. Each ink has unique spectral signature. This signature is different even for same ink but for old drawn and fresh drawn lines, because inks spectral features are subject of slow temporal changes. Dedicated hyperspectral data processor can uncover those signatures and bring the result into easy understandable form of the 2D / 3D image. Several patent pending spectral signature unwrapping algorithms were developed as a result of cooperation between ScienceGL and UEKAE. This is basic operation principle of ForensicXP and MST-2 hyperspectral instruments. Hyperspectral imaging was found to be the most powefull tool to view obliterated writings such as graphite, printer, ink and mixed obliterations. One might ask "When obliteration detected is it possible to distinguish which line was drawn the first or, in other words, is it possible to solve classical forensic "line sequence" problem with hyper-spectral approach. This more complicated part of the forensic examiner job stars from this point. As our research has shown in recent few years the answer is "yes", provided that high-resolution and sensitive enough data acquisition hardware is used for hyper-spectrum measuring and that the hyperspectral data is processed with adequate smart computing spectral signature unwrap algorithm. Independently similar research results were reported by Oak Ridge Institute for Science and Education- FBI Laboratory Research Division. See citation and link below [1]

1. Nondestructive new principle in document examination that utilizes physically measurable (unprejudiced, i.e. true) spectral data analysis principles
2. Effective 16 bits hyper-spectral data acquisition per , that is 16 bit per hyper-spectrum point, and effective 64 bits per pixel.
3. High spatial resolution with 1.5 Mega pixel camera
4. Highest commercially available sensitivity / resolution of the hyper-spectral imaging
5. Automatic hand free hyper-spectrum data recording from questioned document
6. Automatic data processing with patent pending algorithms of spectral signatures reveal
7. Patent pending ink spectral signature unwrap algorithm of highest possible sensitivity
8. 2D and 3D result visualization and reporting for maximum human perception
9. Line sequence drawing problem solution in about 95% of the cases

Forensic 3D digital image that resulted from questioned document measured with ForensicXP and processed with 4D hyper-spectrum processor. Obliterated writing is unambiguously detected.

[1] Hina Ayub, Diane Williams
     "The Role of Hyperspectral Imaging in the Visualization of Obliterated Writings"
     2006 APS March Meeting, March 13–17, 2006; Baltimore, MD, USA
     Citation "We report the use of hyperspectral imaging to successfully view
                   obliterated writings in which a ``true black'' ink obliterated graphite
                    as well as graphite/graphite and ink/ink obliterations"

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