Standard Active Last Updated: Jan 23, 2023
ASTM E3235-21

Standard Practice for Latent Print Evidence Imaging Resolution

Significance and Use

5.1 The procedure described in this document is in accordance with current SWGFAST guidelines (6), as well as National Institute of Standards and Technology (NIST) standard (7), which specify 1000 pixels per inch (ppi) at 1:1 as the minimum scanning resolution for latent print evidence. This standard appears primarily to be historical and directed towards scanners, rather than cameras, though recent studies suggest that it is suitable for capturing Level 3 detail (8).

5.2 While the 1000 ppi resolution standard permits the capture of level three detail in latent prints, it does not mean that any image recorded at a lower resolution would necessarily be of no value for comparison purposes. Such an image could have captured level two details sufficiently for comparison. However, there are some latent print impressions that are so degraded or contain such limited quantity of information that at least 1000 ppi resolution is required to conduct an accurate examination. Some automated fingerprint identification systems require 1000 ppi for submission purposes. The relationship between machine (optical) resolution and achievable resolution (sometimes called resolving power) can vary greatly by manufacturer (8).

Scope

1.1 This practice provides recommendations on the resolving power that enables recording of Level 3 details of latent print evidence that are suitable for comparison purposes using a digital camera, a flatbed scanner, or other image capture device. These recommendations take into consideration the minimum resolution requirements for utilizing the photographs for comparison.

1.2 This practice describes procedures that can be used to verify the resolving power of such imaging systems and recommends equipment to be used.

1.3 Certain commercial equipment, instruments, or materials are used in this document as representative examples to more clearly explain the procedures. Such use does not imply a recommendation or endorsement.

1.4 This standard is intended for use by competent forensic science practitioners with the requisite formal education, discipline-specific training (see Practice E2917), and demonstrated proficiency to perform forensic casework.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

Price:
Contact Sales
Related
Reprints and Permissions
Reprints and copyright permissions can be requested through the
Copyright Clearance Center
Details
Book of Standards Volume: 14.02
Developed by Subcommittee: E30.12
Pages: 9
DOI: 10.1520/E3235-21
ICS Code: 35.240.15; 37.040.99