Forensic Photography Overview

A comprehensive set of flashcards covering key vocabulary and concepts from Forensic Photography.

Forensic Photography

A specialized area of photography that captures images to accurately preserve forensic evidence for use in legal proceedings.

Scientific Method

A systematic approach used by forensic photographers to organize and document evidence, ensuring objectivity and reproducibility.

Chain of Custody

Procedures that account for the integrity of evidence by tracking its handling and storage from the crime scene to the courtroom.

Evidentiary Photos

Photographs that serve as evidence in court, documenting a crime scene or forensic detail in a fair and accurate manner.

Digital Imaging Protocols

Best practices (often following SWGIT or OSAC guidelines) for handling, storing, and authenticating digital photographs.

Visual Representation

A depiction of an object or scene that helps convey information about it to a jury or investigator.

Image Capture

The technical process of utilizing light and sensors to document physical evidence.

Perspective

The position from which a subject is observed; incorrect perspective can distort the spatial relationships between evidence items.

Photo Log

Documentation detailing the camera settings, subject, location, and person taking the photograph for every frame captured.

Color References

Standardized charts used to ensure that the colors in the final print represent the true colors of the evidence.

Unique Color Reference

A specific reference that can be maintained along with photographic evidence for consistency in one specific case.

Universal Color Reference

Commonly accepted reference materials, such as the Kodak 18\% Gray scale or Macbeth ColorChecker.

Macro Lens

A specialized lens capable of 1:1 magnification, essential for detailed close-ups of small evidence like fingerprints or fiber.

Oblique Lighting

Lighting directed at a low angle (15^{\circ} to 45^{\circ}) to enhance texture and detail in items like footwear impressions.

Ghost Photography

An early form of photographic deception; in forensics, it serves as a historical case study for image authentication.

Bruise Documentation

Capturing the size and color of tissue damage; requires repeated photography over several days to track pattern changes.

Deep Bruising

Internal injuries that may not be immediately visible on the skin's surface, often requiring specialized lighting to detect.

Infrared Light

Light in the 700-1100\text{ nm} range; used to see blood through dark fabrics or to visualize deep bruising underneath the skin.

Visible Light

The spectrum from 400\text{ nm} to 700\text{ nm} used for standard documentation of crime scenes and injuries.

Digital Image Resolution

The density of pixels; high resolution is required for examination-quality photos (minimum 1000\text{ PPI} or the equivalent digital sensor data).

Camera Metadata

Electronic EXIF data containing timestamps, GPS coordinates, and camera settings (f-stop, shutter speed) used to authenticate evidence.

Victim Documentation

A systematic photographic record of a victim's condition, including orientation photos and close-ups of specific injuries.

Bloodstain Pattern Analysis (BPA)

The use of photography to document the shape and distribution of blood to reconstruct the events of a crime.

Focal Length

Measured in millimeters (mm); affects the field of view and perceived distance between objects.

Staging Photographs

Arranging elements for clarity; in forensics, this must be done carefully to avoid misrepresenting the original scene.

Evidentiary Exclusion

A judicial ruling that photographs are inadmissible, often due to poor chain of custody or being 'more prejudicial than probative.'

Field Documentation

Notes and sketches made on-site to support the photographic record and provide context for orientations.

Comparison Photography

The practice of capturing images of evidence alongside a known standard for late laboratory identification.

3-D Representation

The use of lighting (shadows) and perspective to represent depth in a 2-D image surface.

Photographic Authentication

The process of verifying that an image has not been altered through hashing algorithms (MD5 or SHA-1) and metadata checks.

Fill-Flash Technique

Using a secondary flash to illuminate deep shadows in high-contrast outdoor scenes.

Judicial Standards

Rules like the Frye or Daubert standards that determine if a scientific technique (like digital enhancement) is admissible.

The Exposure Triangle

The relationship between Aperture, Shutter Speed, and ISO which determines the total light reaching the sensor.

Aperture (f-stop)

The opening in the lens; smaller apertures (high f-numbers like f/22) provide a greater depth of field.

Shutter Speed

The duration the sensor is exposed to light; fast speeds stop motion, while slow speeds require a tripod.

ISO Sensitivity

The sensor's sensitivity to light; higher ISO settings allow for low-light photos but introduce digital 'noise.'

Depth of Field (DOF)

The range of distance in front of the camera that appears sharp; forensic close-ups require maximum DOF to keep all evidence details in focus.

ABFO No. 2 Scale

The standard L-shaped scale used to provide accurate measurement and color/grayscale correction in forensic photos.

Overall Photographs

Wide-angle views of the entire scene (taken from corners or center) to show the general condition and layout.

Mid-Range (Relationship) Photographs

Photos that show an item of evidence in relation to a fixed landmark in the scene.

Close-up Photographs

High-detail photos of evidence; taken at a 90^{\circ} angle with and without a scale present.

Sensor Artifacts

Errors in digital image files (like blooming or moir) that can be mistaken for physical evidence.

RAW File Format

Unprocessed sensor data; the 'digital negative' preferred in forensics because it contains all original data without lossy compression.

JPEG Compression

A lossy format that discards data to save space; generally avoided for 'original' forensic captures as it introduces artifacts.

Alternate Light Source (ALS)

Used to induce fluorescence in biological fluids, fibers, and fingerprints; requires the use of barrier filters on the camera lens.

Fluorescence

The emission of light by a substance that has absorbed light; critical for visualizing latent prints and body fluids.

Cross-Polarization

The use of polarizing filters on both the light source and the lens to eliminate 'hot spots' or glare on reflective surfaces.

Painting with Light

A long-exposure technique (30+ \text{ seconds}) where a flash is fired multiple times from different angles to illuminate large dark scenes.

Coaxial Lighting

A technique using a piece of glass to reflect light onto a flat, shiny surface; used to photograph fingerprints on glass or mirrors.

Transmitted Lighting

Lighting that passes through the object from behind (backlighting) to reveal watermarks or internal details in translucent evidence.

Dynamic Range

The ratio between the brightest and darkest parts of a scene that a camera can capture without losing detail.

Spherical Imaging

A technique using specialized cameras to capture a 360^{\circ} view of a crime scene for virtual walkthroughs.

Photogrammetry

The science of making measurements from photographs to create 3D models or maps of a scene.

Scales and Perspective

Scales must be placed on the same plane as the evidence to ensure that measurements are mathematically accurate.

Bogen/Manfrotto Standard

Industry-standard tripods and equipment used to ensure camera stability during forensic documentation.

Metadata Validation

Ensuring the internal clock of the camera is synchronized with the actual time to maintain accurate logs.