Fingerabdruck eines Fotos
Aus der Technology Review April 2006:
We present a new approach to the problem of camera identification from images based on pixel non-uniformity noise, which is a unique stochastic characteristic for both CCD and CMOS sensors. The presence of this noise is established using correlation as in detection of spread spectrum watermarks. Reliable identification is possible even from images processed using lossy JPEG compression, resizing, and point intensity transformations (e.g., gamma correction).
As the identifying pattern is a semi-robust spread-spectrum watermark, it should not be surprising that malicious processing becomes possible if an attacker has the camera in possession or has access to many images taken by the camera. In particular, we have shown that it is possible to remove the pattern noise from an
image beyond detection using or plant a given reference pattern into another image.
An interesting question that we are currently investigating is whether it is possible to use the proposed technique on smaller blocks for identification of tampered
areas (forgeries).
Laut TR ist insbesondere das FBI an diesem Verfahren interessiert für die Untersuchungen wegen Kinderpornografie.
DIGITAL “BULLET SCRATCHES” FOR IMAGES (pdf 272 kb)