RAW File Format
Definition
The unprocessed output of a digital camera sensor, stored before demosaicing, white balance, or tonal curve application. Preserves full bit-depth and all sensor data; the forensic standard for image capture.
- Stage captured
- Before demosaicing, white balance, tonal curve
- Bit depth
- Full sensor bit-depth preserved
- Court status
- Forensic standard for image capture
- Contrast
- Unlike JPEG, not lossily compressed at capture
Common questions
Why do courts favour RAW files over processed formats for digital imaging evidence?+
Because a RAW file has not had any irreversible camera-side processing or compression applied, it better supports an argument that the image has not been altered from what the sensor recorded, and any enhancement performed later can be shown as a documented, reversible step.
Can a RAW file itself be tampered with?+
Yes, RAW files can still be edited or replaced, so admissibility depends on proper handling: hashing the file at capture, controlled chain of custody, and documenting any subsequent processing, not on the RAW format alone.
Related terms
- BSA 2023 § 63
- The electronic record admissibility provision (replacing IEA § 65B), requiring a certificate from a person in a responsible official position confirming the...
- Daubert Standard
- The US federal evidentiary standard (Daubert v. Merrell Dow Pharmaceuticals, 1993) requiring that expert testimony be based on scientifically valid methods with...
- DNG (Digital Negative)
- Adobe's open-standard RAW format providing a vendor-neutral archival container for camera sensor data; accepted as an archival format by SWGDE and several...
- EXIF (Exchangeable Image File Format)
- A metadata standard embedded in JPEG and TIFF files by capture devices. EXIF fields record camera make and model, lens data, exposure...
- Image Enhancement
- Processing of a digital image to improve the visibility of features already present in the original data; permitted under SWGIT, FBI, and...
- JPEG Compression
- A lossy codec that divides an image into 8×8 pixel blocks, applies the discrete cosine transform, quantises the coefficients, and entropy-codes the...
- MD5
- A 128-bit hash algorithm widely used in legacy forensic systems; known collision vulnerabilities (Wang and Yu, 2004) mean SHA-256 or SHA-3 are...
- R V. Tobi (2019)
- UK Court of Appeal decision affirming that forensic image enhancement is permissible provided the original is preserved, the enhancement steps are documented,...
- SHA-256
- A Secure Hash Algorithm 2 variant producing a 256-bit hash; the current recommended standard for forensic digital evidence integrity verification under SWGDE,...
- SWGDE
- Scientific Working Group for Digital Evidence. A US multi-agency body that publishes consensus best-practice documents for digital forensic disciplines, including image authentication,...
- Write-Once Media
- Optical or other media (DVD-R, BD-R) that physically prevents modification after initial recording; the preferred first-write medium for forensic digital images as...