PRNU, or photo-response non-uniformity, is the subtle fixed-pattern noise produced by an image sensor. Every camera sensor has tiny manufacturing differences, so the noise it leaves in photos can act like a fingerprint. Forensic analysts use PRNU to help attribute an image to a specific device and to look for signs that a file has been edited, re-encoded, or composited.
In cyber security and digital investigations, PRNU matters because it gives investigators an independent source of evidence about image origin. Attackers who want to weaken attribution may try to strip, distort, or imitate this sensor pattern so a picture is harder to tie to a camera. Defenders counter by preserving originals, comparing PRNU against known device profiles, and combining it with metadata, hashes, and other provenance checks rather than relying on one signal alone.