ZERO: a Local JPEG Grid Origin Detector Based on the Number of DCT Zeros and its Applications in Image Forensics
Tina Nikoukhah, Jérémy Anger, Miguel Colom, Jean-Michel Morel, Rafael Grompone von Gioi
published
2021-12-16
reference
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

Communicated by Jose-Luis Lisani
Demo edited by Jérémy Anger, Tina Nikoukhah

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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