A Novel Method for Detecting Cropped and Recompressed Image Block

Abstract

One of the most common practices in image tampering involves cropping a patch from a source and pasting it onto a target. In this paper, we present a novel method for the detection of such tampering operations in JPEG images. The lossy JPEG compression introduces inherent blocking artifacts into the image and our method exploits such artifacts to serve as a 'watermark'for the detection of image tampering. We develop the blocking artifact characteristics matrix (BACM) and show that, for the original JPEG images, the BACM exhibits regular symmetrical shape; for images that are cropped from another JPEG image and re-saved as JPEG images, the regular symmetrical property of the BACM is destroyed. We fully exploit this property of the BACM and derive representation features from the BACM to train a support vector machine (SVM) classifier for recognizing whether an image is an original JPEG image or it has been cropped from another JPEG image and re-saved as a JPEG image. We present experiment results to show the efficacy of our method.

Exposing Digital Forgeries From JPEG Ghosts

“…Estimating the quantization from only the underlying DCT coefficients is both computationally nontrivial, and prone to some estimation error, which leads to vulnerabilities in the forensic analysis. In comparison to [13], our approach does not require that the image be cropped in order to detect blocking inconsistencies. In addition, our approach can detect local tampering unlike the global approach of [13] which can only detect an overall crop and re-compression.…”

“…In comparison to [13], our approach does not require that the image be cropped in order to detect blocking inconsistencies. In addition, our approach can detect local tampering unlike the global approach of [13] which can only detect an overall crop and re-compression. And in comparison to [14], our approach, although likely not as powerful, is computationally much simpler and does not require a large database of images to train a support vector machine.…”

“…Luo, et. al developed a technique to detect inconsistencies in JPEG blocking artifacts that arise from mis-alignments of JPEG blocks relative to their original lattice [13]. And, He et.…”

A Novel Method for Block Size Forensics Based on Morphological Operations

“…For example, the authors in [7] proposed a method to determine whether a BMP image has been JPEG compressed previously by detecting the block artifact effects. It has also been shown that JPEG image splicing [8] and MPEG recompression [9] can be exposed based on the block artifacts. In most prior literatures, it is always assumed that the image is compressed by a known scheme such as JPEG, MPEG with a fixed block size of 8 × 8 or 16 × 16.…”

“…To our knowledge, most existing works on block artifacts are proposed with the purposes of image restoration and enhancement, only a few are for forensics purposes [7,8,9,10]. It is well known that the block artifact is bad for the quality of the image.…”