ASTM E3235-21 PDF

Full title and description

ANSI/ASTM E3235-21 — Standard Practice for Latent Print Evidence Imaging Resolution. This practice provides recommendations for the resolving power and imaging parameters needed to record latent friction ridge (latent print) detail suitable for examination and comparison, with emphasis on capturing Level 3 detail in forensic latent print evidence.

Abstract

This practice describes imaging-resolution guidance (including recommended pixels-per-inch and capture conventions), parameters for scanner and camera capture, and related image-quality considerations (dynamic range, focal considerations, and documentation) to support reliable latent print recording and subsequent analysis. The standard documents minimum recommended scanning resolution to capture Level 3 detail and positions those recommendations within current forensic imaging guidance.

General information

• Status: Published / Active.
• Publication date: 2021 (designation E3235-21; current edition approved Sept. 1, 2021).
• Publisher: ASTM International (ANSI/ASTM).
• ICS / categories: 35.240.15; 37.040.99 (forensic imaging / photography-related classifications).
• Edition / version: E3235-21 (2021).
• Number of pages: 9 pages.

Key registry note: this standard is listed on the OSAC Registry (added to the registry in 2022).

Scope

This practice provides recommendations on imaging resolution and related imaging parameters sufficient to record Level 3 detail in latent prints. It addresses recommended resolving power for scanners and other imaging devices, minimum capture conventions (for example, guidance that supports a 1:1 capture at high pixel density), and ancillary imaging considerations such as sensor dynamic range, focus/focal length effects, and image documentation necessary to support forensic examination and comparison. The practice is intended as guidance for forensic practitioners and laboratories rather than a prescriptive laboratory protocol.

Key topics and requirements

• Recommended minimum scanning resolution to enable capture of Level 3 detail (commonly referenced guidance supporting ~1000 pixels per inch at 1:1 for many latent print scanning scenarios).
• Guidance on device selection and configuration for latent print imaging (scanner vs camera considerations; resolving power; focal and optical considerations).
• Image-quality factors such as dynamic range and sensor limitations; importance of calibration and documentation.
• Metadata and documentation recommendations to ensure traceability of capture settings and conditions.
• Notes on applicability: higher resolution does not guarantee useful evidence in all cases, and lower-resolution captures may still be suitable for some level-2 comparisons depending on the latent’s condition.

These topics and requirements are summarized from the practice and from supporting forensic imaging guidance referenced within the standard.

Typical use and users

Intended users include forensic latent print examiners, crime laboratory imaging technicians, digital evidence specialists, law-enforcement evidence technicians, forensic laboratory managers, and vendors of forensic imaging equipment. Typical uses are establishing capture procedures for latent print scanning or photographic documentation, specifying minimum imaging requirements in laboratory policies, and guiding procurement and validation of imaging devices for latent print capture.

Related standards

Referenced or related documents include ASTM terminology and forensic-imaging standards cited within the practice (for example, ASTM E2916 and ASTM E1732 as relevant terminology/guides), national forensic imaging guidance (SWGFAST/NIST-related guidance), and other ASTM E30 committee publications addressing digital and multimedia evidence practices. Users commonly consult those documents together with E3235-21 when establishing or reviewing latent print imaging protocols.

Keywords

latent print, friction ridge, imaging resolution, pixels per inch (ppi), Level 3 detail, scanner, digital camera, resolving power, dynamic range, forensic imaging, ASTM E3235-21.

FAQ

Q: What is this standard?

A: ANSI/ASTM E3235-21 is a practice that provides recommendations for imaging resolution and related capture parameters to support recording of latent friction ridge evidence (latent prints). It is intended as guidance for forensic practitioners documenting latent prints.

Q: What does it cover?

A: It covers recommended resolving power and capture conventions (including guidance that supports high-resolution capture to enable Level 3 detail), device considerations (scanners vs cameras), and image-quality factors such as dynamic range and documentation of capture settings. The text explains when higher resolution is likely needed and notes that lower-resolution captures may still be useful for some comparisons.

Q: Who typically uses it?

A: Forensic latent print examiners, crime-lab imaging staff, digital evidence specialists, law-enforcement evidence technicians, lab managers, and equipment vendors use this practice to set imaging policies, validate capture workflows, and procure suitable imaging devices.

Q: Is it current or superseded?

A: The designation E3235-21 indicates the 2021 edition; it is published and listed on the OSAC Registry. Users should confirm whether a later revision has been issued before adopting the text for long-term policy—this summary reflects the E3235-21 edition.

Q: Is it part of a series?

A: E3235-21 is part of ASTM Committee E30 (Forensic Sciences) outputs and is related to other E30 documents addressing terminology and practices for digital and multimedia evidence (for example, ASTM E2916 and ASTM E1732). It is intended to be used alongside those standards and other national forensic imaging guidance.

Q: What are the key keywords?

A: Latent print, imaging resolution, Level 3 detail, 1000 ppi (recommended scanning guidance context), scanner, camera, resolving power, dynamic range, forensic imaging.