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Robust reversible watermarking (RRW) is a potential technology for copyright protection and integrity authentication due to its ability in both robustness and reversibility. Currently, there is no detailed report on RRW of JPEG images. In this paper, we propose an RRW algorithm of JPEG images by selecting quantized discrete cosine transform coefficients to construct robust features for watermarking. In the proposed algorithm, a watermark sequence can be embedded into a JPEG image by shifting the histogram of its constructed robust features. For less embedding distortion, smaller file size, and higher structural similarity, an evaluation method has been designed to select those appropriate frequency bands for watermarking. On the receiver side, the watermark can be accurately extracted by reconstructing the robust features, and the original JPEG image can be restored losslessly by performing the inverse operation of the histogram shifting. Experimental results show that the watermark is robust to common image processing operations (e.g., JPEG recompression, JPEG2000 compression, WebP compression, and additive white Gaussian noise), and can effectively resist those attacks from the lossy channels in real life, such as the most popular apps Instagram and WeChat. • Propose a robust reversible watermarking algorithm of JPEG images. • Propose a method to construct robust features in JPEG images. • Design an evaluation method to select appropriate frequency bands for watermarking. • The proposed algorithm achieves reversibility for JPEG images and strong robustness. [ABSTRACT FROM AUTHOR]

Recent research shows that the security performance of JPEG image steganography can be improved by developing an accurate statistical model to characterize the correlations between Discrete Cosine Transform (DCT) coefficients. In this paper, a novel JPEG steganographic scheme called J-CRF is proposed to characterize the correlations between DCT coefficients using a pairwise Conditional Random Field (CRF) model, in which the correlated DCT coefficient pairs are modeled as bivariate Gaussian random variables. Under the framework of pairwise CRF, the proposed scheme formulates the problem of minimizing the statistical detectability within the Gaussian image model as the minimization of the sum of a series of unary and pairwise potentials, both of which are utilized to measure the local detectability of embedding messages in the DCT coefficient pairs. All the potentials associated with statistical detectability are formalized as the KL divergence between the statistical distributions of the cover and the stego. Experimental results demonstrate that the proposed J-CRF can outperform other SOTA JPEG steganographic schemes, e.g., J-UNIWARD, J-MiPOD, and JEC-RL, in resisting the detection of various advanced steganalyzers. In addition, the performance of J-CRF could be further boosted by reformulating it as the weighted sum of unary and pairwise potentials, called J-CRFW. • Propose a novel JPEG steganographic scheme J-CRF using Conditional Random Field (CRF). • Characterize the correlations between DCT coefficients using pairwise CRF. • Cast the task of JPEG steganography as minimizing the detectability with CRF. • Improve J-CRF by reformulating the sum of potentials in a weighted manner. • Demonstrate superior security performance over other SOTA schemes. [ABSTRACT FROM AUTHOR]

• Design a block difference model to select similar DCT blocks by combining the metrics of texture, location, and template matching. • Number of similar DCT blocks involved in Laplacian distribution estimation is selected adaptively. • Block difference threshold and the distance threshold are set further to improve the accuracy of AC coefficient distribution estimation. [Display omitted] Reversible data hiding (RDH) for JPEG images has attracted extensive attentions in recent years. As far, a number of related schemes have been proposed, which enhance the embedding performance by improving the strategies such as frequency selection and block sorting to choose appropriate embedding coefficients with the histogram shifting mechanism. Nevertheless, the existing methods do not fully consider the characteristics of DCT coefficients and lack accurate measurement on the embedding distortion. To address the above problems, we propose an improved general framework of RDH for JPEG images based on the Laplacian distribution model. The block difference model is first established for the alternating current (AC) coefficients fitting. Subsequently, the scale parameter is calculated to estimate the embedding efficiency of each AC coefficient, and the coefficients with high embedding efficiency are preferentially selected for embedding. Furthermore, the proposed framework can be combined with other JPEG RDH methods based on quantized DCT coefficient modification. Experimental results demonstrate that better performance in terms of both visual quality and file size preservation can be achieved with the proposed scheme compared with the state-of-the-art RDH schemes for JPEG images. [ABSTRACT FROM AUTHOR]

The joint photographic experts group (JPEG) is the most popular format of digital image. In this paper, a novel reversible data hiding scheme based on JPEG image is proposed. In JPEG image, quantified DCT (discrete cosine transform) coefficients with different frequencies will yield different capacities and embedding distortions. To reduce the total distortion for the marked image, we select coefficients from frequencies yielding less distortions for embedding, and then an advanced block selection strategy is applied to always modify the block yielding less simulated distortion firstly until the given payloads are completely embedded. Experimental results show that the proposed method can keep good visual quality with small bitstream expansion. [ABSTRACT FROM AUTHOR]

• An efficient mathematical model for optimized Huffman table is constructed according to the embedding efficiency of RS. • The VLC mapping is established using both AC and DC Huffman tables. • A search algorithm is designed to find a feasible solution. Lossless data hiding is a data hiding method that embeds secret data without distortion. In JPEG images, it generally refers to modifying the bitstream of the Huffman table and DCT coefficient, also known as the method of Huffman table modification. Currently, most JPEG lossless data hiding methods use coding redundancy in the default AC Huffman table. However, this preference is deficient in two ways. On the one hand, the Huffman tables of most JPEG images are optimized to save storage and increase transmission speed, causing the approach to be unavailable. In this paper, the embedding efficiency of each Run-Size (RS) has been analyzed, and an efficient mathematical model for the optimized Huffman table is established. On the other hand, current schemes tended to modify the AC Huffman table while ignoring the DC one. This is because the redundancy presented in the DC Huffman table is hard to exploit. In contrast, the modification on both optimized AC and DC Huffman tables (OAC, ODC) has been implemented in this paper. The experimental results show that the proposed scheme is superior in embedding capacity, file size preservation, and complexity without distortion compared to the state-of-the-art methods. [ABSTRACT FROM AUTHOR]

• Definition of texture complexity and similarity measurement of DCT blocks. • Fitting the AC coefficient distribution based on block complexity. • Coefficient-first selection strategy for reversible data hiding. • Adaptive embedding strategy for different embedding payloads. Joint photographic experts group (JPEG) is the most commonly used image format on the Internet, and using reversible data hiding (RDH) technology to verify its authenticity and integrity is of great significance. So far, many RDH algorithms for JPEG image have been proposed, which improve the performance of the algorithm via block sorting, frequency selection and other adaptive strategies. In this paper, a new JPEG RDH method based on coefficient-first selection strategy is proposed. In our new method, the distribution models of alternating current (AC) coefficients belonging to different discrete cosine transform (DCT) coefficient blocks are constructed first, and then the distortion value of each AC coefficient can be calculated through the estimated probability density function of the constructed coefficient model. In the embedding process, the coefficients with low distortion values will be preferentially selected for data hiding. Various experimental results demonstrate that compared with the state-of-the-art JPEG RDH methods, our proposed may have better visual quality and less increase of file storage size. [ABSTRACT FROM AUTHOR]

• A new method of coefficient paring between blocks is adopted, which can generate more coefficient pairs that are good for data embedding. • Based on the statistical characteristics of the coefficient pairs, an optimized coefficient pair mapping is presented, in which the transfer mode with higher embedding efficiency is preferentially assigned to the coefficient pairs with higher occurrence frequency. • The frequency sorting is improved by more accurately estimating the embedding efficiency of the frequency positions. Due to the good balance between file size and visual quality, JPEG images are widely used in our daily lives. Many reversible data hiding (RDH) schemes have been developed for JPEG images, most of which are based on the modification of one-dimensional (1D) histograms of DCT coefficients. Recently, two-dimensional (2D) histograms of DCT coefficients are used to improve embedding efficiency. However, the existing coefficient pairing, coefficient pair mapping and embedding order can be further optimized. In this paper, a new RDH scheme for JPEG images based on 2D histogram modification is proposed. First, according to the statistical distribution of the AC coefficients, two non-zero coefficients with the same frequency in adjacent blocks, instead of two neighboring coefficients within the same block, are paired. More coefficient pairs with higher embedding efficiency can be obtained. Then, an optimized coefficient pair mapping is presented, more specifically, the coefficient pairs that occur more frequently are given priority to use the transfer mode with higher embedding efficiency. Lastly, a new method is proposed to accurately estimate the embedding efficiency of different frequencies. The data is embedded into the coefficient pairs at the frequency position where the embedding efficiency is higher. Extensive experiments on several commonly-used images and two popular image databases show that our proposed scheme can achieve better visual quality and smaller file size increments compared to the state-of-the-art RDH schemes for JPEG images. [ABSTRACT FROM AUTHOR]

Abstract: This paper proposes a novel fragile watermarking scheme for JPEG image authentication. The watermark is generated by folding the hash results of quantized coefficients, and each block is used to carry two watermark bits using a reversible data-hiding method. Because modification to the cover is small, the visual quality of watermarked image is satisfactory. On the receiver side, one may attempt to extract the watermark and recover the original content. By measuring mismatch between the watermark data extracted from the received image and derived from the recovered content, the blocks containing fake content can be located accurately, while the original information in the other blocks is retrieved without any error as long as the tampered area is not extensive. [Copyright &y& Elsevier]

• Based on the estimated distributions of DCT coefficients, the embedding distortion of each block can be estimated more accurately. • A metric named embedding efficiency is defined for each frequency, and the used frequencies of higher embedding efficiency can be remembered with just a number instead of a frequency map. • The RDH scheme based on the new block ordering and frequency selection achieves better visual quality and file size preservation. JPEG images are widely used in daily life. Reversible data hiding (RDH) in JPEG images is useful for many applications. How to avoid image distortion and preserve file size is very important for RDH in JPEG images. In this paper, a novel RDH scheme is proposed for JPEG images based on improved block ordering and frequency selection. The distortion that may be caused by the data embedding in each block is estimated more accurately based on the DCT coefficient distribution, and the blocks that result in less distortion will be firstly used for data embedding. Moreover, the non-zero AC coefficients with the frequencies having higher embedding efficiency will be used preferentially to further reduce image distortion. Consequently, less side information on frequency selection is needed for data extraction and image recovery with our scheme. Extensive experiments are conducted on several typical images and 500 images randomly selected from BOSSbase image database, and the numerical results demonstrate that better performance in terms of visual quality and file size preservation can be achieved with the proposed scheme compared to the state-of-the-art RDH schemes for JPEG images. [ABSTRACT FROM AUTHOR]