Evidence-Grade Digital Imaging
Definition
Capture and storage of digital images in a manner that preserves chain-of-custody integrity, typically through hash-based fingerprinting of the original RAW or DNG file at the moment of capture.
- Core requirement
- Hash fingerprint of the original file generated at capture
- File formats
- RAW or DNG, preferred over compressed JPEG for evidentiary use
- Purpose
- Proves the image has not been altered since capture
- Applies to
- Crime scene photography, 3D scan source imagery, videography stills
Common questions
Why use RAW or DNG instead of JPEG for evidence photography?+
RAW and DNG store unprocessed sensor data with no lossy compression or in-camera adjustment, so the file better represents what the sensor captured and gives a stable baseline for hashing. JPEG compression can also introduce artifacts that complicate later analysis.
What happens if the hash of an evidentiary image no longer matches?+
A mismatch signals the file has been altered, whether through editing, format conversion, or corruption, and the image's evidentiary value is compromised. Any legitimate processing, such as producing a viewing copy, must be done on a duplicate, leaving the original and its hash untouched.
Related terms
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- BNSS Section 105 Videography
- The mandatory continuous video recording of search and seizure under the Bharatiya Nagarik Suraksha Sanhita 2023.
- Drone Overhead Capture
- Aerial photography or videography from an unmanned aerial vehicle, used for outdoor scenes that exceed ground-level photographic coverage.
- Point Cloud
- The raw data product of a LiDAR survey: a set of 3D coordinates (X, Y, Z) for each laser return, classified by...