RAW format
Definition
A camera capture format that records unprocessed sensor data, preserving all original exposure and colour information. RAW files are preferred over JPEG for forensic photography because the original data is retained and any post-processing is fully auditable.
- Common RAW formats
- DNG, CR2, NEF, ARW
- What RAW preserves
- Unprocessed sensor data, original exposure, colour information
Common questions
Why is RAW format better than JPEG for forensic photography?+
RAW files preserve all original exposure and colour information from the sensor without processing. This means you keep the full forensic data and any post-processing changes are fully auditable, making RAW the preferred format when evidence documentation matters.
What's stored inside a RAW file?+
A RAW file is a container (like DNG, CR2, NEF, or ARW) that holds the unprocessed or minimally processed photosite values directly from the camera sensor. This preserves more forensic information than any other capture format.
Can RAW files be edited without changing the original data?+
Because edits are applied separately and the raw sensor data is preserved, any post-processing is fully auditable. This is why RAW is preferred for forensic photography where documentation integrity matters.
Related terms
- Bayer CFA
- A colour filter array arranged in a repeating 2×2 mosaic of red, green (×2), and blue filters over the sensor. Each photosite...
- Colour checker
- A calibrated chart of known colour patches (typically the Macbeth ColorChecker or equivalent) photographed in the same light as the scene, used...
- Colour space
- A defined mapping between numerical RGB values and real-world colours. sRGB is the web default with a smaller gamut; Adobe RGB covers...
- Context plan
- A hand-drawn plan at a standard scale (typically 1:10 or 1:20) showing the outline and internal features of one context. Drawn before...
- Demosaicing
- The interpolation step that reconstructs all three colour channels at every pixel from the single-channel Bayer mosaic. The algorithm used is camera-specific...
- Fixed-pattern noise (FPN)
- Any repeatable, spatially correlated noise in an image sensor, as opposed to random shot noise. PRNU and DCNU are both forms of...
- 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...
- Photographic log
- A written record, kept on site alongside the context records, that logs each photograph with its file name, date, time, photographer, subject...
- Scale bar
- A physical ruler or L-shaped measuring device placed in the field of view before a photograph is taken. It provides a known...
- Section drawing
- A vertical cut through the excavated sequence, drawn at 1:10 or 1:20, showing the relative positions, depths, and angles of all contexts...
Explained in these topics
- Site Photography and IllustrationA camera capture format that records unprocessed sensor data, preserving all original exposure and colour information. RAW files are preferred over JPEG for fo...
- Digital Image Fundamentals: Pixels, Sensors, and FormatsA proprietary or standardised container (DNG, CR2, NEF, ARW) that stores the unprocessed or minimally processed photosite values from the sensor. RAW preserves...