A new article is available in IPOL: http://www.ipol.im/pub/art/2021/390/
Tina Nikoukhah, Jérémy Anger, Miguel Colom, Jean-Michel Morel, and
Rafael Grompone von Gioi,
ZERO: a Local JPEG Grid Origin Detector Based on the Number of DCT Zeros
and its Applications in Image Forensics,
Image Processing On Line, 11 (2021), pp. 396–433.
https://doi.org/10.5201/ipol.2021.390
Abstract
This work describes a method for detecting JPEG compression as well as
its grid origin. The JPEG algorithm performs a quantization of the DCT
coefficients of non-overlapping 8 x 8 blocks of images, setting many of
those coefficients to zero. The method described here exploits these
facts and identifies the presence of a JPEG grid when a significant
number of DCT zeros is observed for a given grid origin. This method can
be applied globally to identify a JPEG compression, and also locally to
identify image forgeries when misaligned or missing JPEG grids are
found. The algorithm includes a statistical validation step according to
Desolneux, Moisan and Morel's a contrario theory, which associates a
number of false alarms (NFA) with each tampering detection. Detections
are obtained by a threshold of the NFA, which renders the method fully
automatic and endows it with a false alarm control mechanism.
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