NCJ Number
209807
Journal
Law Enforcement Technology Volume: 32 Issue: 4 Dated: April 2005 Pages: 108,110,113
Date Published
April 2005
Length
5 pages
Annotation
This article outlines the provisions of Appendix F of the FBI's Electronic Fingerprint Transmission Specification (EFTS), which was developed in 1993 with the primary objective of providing objective national standards for ensuring fingerprint image quality for card scan systems and printers.
Abstract
The rationale for this article is to compare where image quality is headed with what has been achieved thus far. In doing this, it is useful to revisit Appendix F of the EFTS. The development of the FBI's Integrated Automated Fingerprint Identification System (IAFIS) required the development of a standard for electronically encoding and transmitting fingerprint image data that would be a common interface for all AFIS systems. It begins with minimum 500-ppi resolution and 8-bit gray scale. In addition, there are six other areas that are measured: geometric image accuracy, modulation transfer function, signal to noise ratio, gray-scale range of image data, and output gray-level uniformity. To determine whether a given livescan system meets these minimum criteria, each vendor submits a set of test image files captured from static test patterns. The expectation is that even though the Appendix F measurements are conducted in a "lab environment," the product will perform as well in a production environment. With the introduction of new standards for image quality coming out of NIST, it is time to look beyond Appendix F for a better understanding of the various factors that affect image quality in real world use of livescans. This challenge is being met with new solutions in livescan systems. Factors addressed in these systems are the subject's finger condition, roll speed, and coated platens. This article also lists a few practical questions that should be asked when comparing livescan systems.