One of the main questions forensic tape authenticity investigations seek to answer is whether a recording on a given tape was produced using a given recorder in a claimed way. A technique that uses so-called ferrimagnetic garnet films, also known as Faraday crystals, makes it possible to take pictures showing the magnetic flux distribution on a tape in such detail that it enables a forensic investigator to answer questions that may arise about the correctness of the claims made. For an in-depth understanding of pictures of these flux distributions, a theory behind the visualization technique is necessary. The derivation of a theoretical transfer function of the visualization technique (spanning from a theoretical input signal to the actual luminance of the pictures) is described and one of a few experiments that were conducted to prove its validity is presented.

Authors: Bouten, Jos; Van Rijsbergen, Mariska; Donkers, Simon
Affiliations: Netherlands Forensic Institute, The Hague, The Netherlands ; Fontys University of Applied Sciences, Eindhoven, The Netherlands(See document for exact affiliation information.)
JAES Volume 55 Issue 4 pp. 257-265; April 2007
Publication Date: April 15, 2007 Import into BibTeX
Permalink: https://www.aes.org/e-lib/browse.cfm?elib=14159

Click to purchase paper as a non-member or login as an AES member. If your company or school subscribes to the E-Library then switch to the institutional version. If you are not an AES member and would like to subscribe to the E-Library then Join the AES!

This paper costs $33 for non-members and is free for AES members and E-Library subscribers.

Learn more about the AES E-Library

E-Library Location: (CD JAES55)   /jaes55/4/pg257.pdf

Start a discussion about this paper!