Quantization Table Estimation in JPEG Images

mva-org.jp

In this paper, we proposed a passive scheme to achieve image forgery. The inconsistent measure of quantization table is characterized to develop the proposed scheme. The proposed scheme is composed of candidate region selection, quantization table estimation, and forgery detection. To select candidate regions for estimating quantization table, a split-and-merge algorithm based on quad-tree decomposition is devised. To estimate the quantization table, we classify the type of PSD and then adjust the estimation algorithm. After quantization table estimation, the variation resulting from the inconsistent of quantization table is utilized to detect tampered regions. The experimental results show that our proposed scheme can not only estimates quantization table correctly but also detect tampered regions well.

2006

The steady improvement in image/video editing techniques has enabled people to synthesize realistic images/videos conveniently. Some legal issues may occur when a doctored image cannot be distinguished from a real one by visual examination. Realizing that it might be impossible to develop a method that is universal for all kinds of images and JPEG is the most frequently used image format, we propose an approach that can detect doctored JPEG images and further locate the doctored parts, by examining the double quantization effect hidden among the DCT coefficients. Up to date, this approach is the only one that can locate the doctored part automatically. And it has several other advantages: the ability to detect images doctored by different kinds of synthesizing methods (such as alpha matting and inpainting, besides simple image cut/paste), the ability to work without fully decompressing the JPEG images, and the fast speed. Experiments show that our method is effective for JPEG images, especially when the compression quality is high.

In this paper, we propose a statistical test to discriminate between original and forged regions in JPEG images, under the hypothesis that the former are doubly compressed while the latter are singly compressed. New probability models for the DCT coefficients of singly and doubly compressed regions are proposed, together with a reliable method for estimating the primary quantization factor in the case of double compression. Based on such models, the probability for each DCT block to be forged is derived. Experimental results demonstrate a better discriminating behavior with respect to previously proposed methods.

2021

The JPEG compression algorithm has proven to be efficient in saving storage and preserving image quality thus becoming extremely popular. On the other hand, the overall process leaves traces into encoded signals which are typically exploited for forensic purposes: for instance, the compression parameters of the acquisition device (or editing software) could be inferred. To this aim, in this paper a novel technique to estimate “previous” JPEG quantization factors on images compressed multiple times, in the aligned case by analyzing statistical traces hidden on Discrete Cosine Transform (DCT) histograms is exploited. Experimental results on double, triple and quadruple compressed images, demonstrate the effectiveness of the proposed technique while unveiling further interesting insights.

Lecture Notes in Computer Science, 2011

Many digital image forensics techniques extracting various fingerprints are dependent on data on digital images from an unknown environment. As often software modifications leave no appropriate traces in images metadata, critical inconveniences and miscalculations of fingerprints arise. This is the problem addressed in this paper. Modeling information noise in image metadata, we introduce a statistical approach to metadata analysis of images from "unguaranteed" sources. Resulting fingerprints are based on JPEG quantization tables.

IEEE Access

Various manipulations on JPEG images introduce single and multiple compression artifacts for forged and unmodified areas respectively. Based on the statistical analysis of JPEG compression cycle and on the finite mixture paradigm, we propose in this paper a modeling framework for AC DCT coefficients of such tampered JPEG images. Its accuracy is numerically assessed using the Kullback-Leibler divergence on the basis of a tampered JPEG image dataset built from six well-known uncompressed color image databases. To illustrate the framework utility, an application in image forgery localization is proposed. By formulating the localization as a clustering problem, we use the plug-in Bayes rule combined with a simple EM algorithm to distinguish between forged and unmodified areas. Numerous experiments show that, when the quality factor of final JPEG compression is high enough, the proposed modeling framework yields higher localization performances in terms of F 1-score than prior art regardless of divers local manipulations. INDEX TERMS DCT coefficients analysis, EM algorithm, forgery localization, multiple JPEG compression, statistical image models, tampered JPEG images.

Proceedings of the First ACM workshop on …, 2009

One of the key characteristics of digital images with a discrete representation is its pliability to manipulation. Recent trends in the field of unsupervised detection of digital forgery includes several advanced strategies devoted to reveal anomalies just considering several aspects of multimedia content. One of the promising approach, among others, considers the possibility to exploit the statistical distribution of DCT coefficients in order to reveal the irregularities due to the presence of a superimposed signal over the original one (e.g., copy and paste). As recently proved the ratio between the quantization tables used to compress the signal before and after the malicious forgery alter the histograms of the DCT coefficients especially for some basis that are close in terms of frequency content. In this work we analyze in more details the performances of existing approaches evaluating their effectiveness by making use of different input datasets with respect to resolution size, compression ratio and just considering different kind of forgeries (e.g., presence of duplicate regions or images composition). We also present possible post-processing techniques able to manipulate the forged image just to reduce the performance of the current state-of-art solution. Finally we conclude the papers providing future improvements devoted to increase robustness and reliability of forgery detection into DCT domain.

Procedia Computer Science, 2015

Today convincing digital forgery can be created without master learning of image editing software. These fake pictures over exceptionally quick media may cause extreme results in the public arena. Passive digital image forensic is an area which uncovers these problems. Since JPEG compression deals with 8 × 8 DCT matrix it makes its own fingerprint which can be utilized to distinguish further forgeries in the picture. In this paper, we have proposed a technique which automatically locates forgery in the image based on histogram of DCT coefficient factors, called as factor histogram. When image undergoes aligned double compression this factor histogram shows peak at current quantization step as well as primary quantization step. Our algorithm searches for absence of such double maxima in block-wise factor histogram to identify tampered region. This method can find copy-move, copy-paste as well as pre-processed forgeries such as rotation and scaling.

Proceedings of the First ACM workshop on Multimedia in forensics - MiFor '09, 2009

One of the key characteristics of digital images with a discrete representation is its pliability to manipulation. Recent trends in the field of unsupervised detection of digital forgery includes several advanced strategies devoted to reveal anomalies just considering several aspects of multimedia content. One of the promising approach, among others, considers the possibility to exploit the statistical distribution of DCT coefficients in order to reveal the irregularities due to the presence of a superimposed signal over the original one (e.g., copy and paste). As recently proved the ratio between the quantization tables used to compress the signal before and after the malicious forgery alter the histograms of the DCT coefficients especially for some basis that are close in terms of frequency content. In this work we analyze in more details the performances of existing approaches evaluating their effectiveness by making use of different input datasets with respect to resolution size, compression ratio and just considering different kind of forgeries (e.g., presence of duplicate regions or images composition). We also present possible post-processing techniques able to manipulate the forged image just to reduce the performance of the current state-of-art solution. Finally we conclude the papers providing future improvements devoted to increase robustness and reliability of forgery detection into DCT domain.

First International Workshop on Systematic Approaches to Digital Forensic Engineering (SADFE'05), 2005

With the advent of digital times, the digital data has gradually taken the place of the original analog data. However, the authenticity of digital data faces a great challenge due to the fact that the digital edit software is ubiquitous. It has aroused the suspicion on the reliability of digital data especially when the digital data renders to the court as the digital evidence. We propose an integrated image authentication system for digital forensics and improve the detection problems of a DCT quantization-based image authentication scheme. The improved detection schemes will effectively solve the detection problems and, at the same time, take into account the reliability, the security, and the practicability of the system. It is expected to reduce the wrong detection probability of the digital evidence. Finally, the improved image authentication schemes will be implemented. If the digital evidence presented to the court is under suspicions, the system is expected to provide accurate information to help the judiciary to make the verdict right and objective.