Middle Frequency Coefficients Research Articles

Robust JPEG steganography based on the robustness classifier

Because the JPEG recompression in social networks changes the DCT coefficients of uploaded images, applying image steganography in popular image-sharing social networks requires robustness. Currently, most robust steganography algorithms rely on the resistance of embedding to the general JPEG recompression process. The operations in a specific compression channel are usually ignored, which reduces the robustness performance. Besides, to acquire the robust cover image, the state-of-the-art robust steganography needs to upload the cover image to social networks several times, which may be insecure regarding behavior security. In this paper, a robust steganography method based on the softmax outputs of a trained classifier and protocol message embedding is proposed. In the proposed method, a deep learning-based robustness classifier is trained to model the specific process of the JPEG recompression channel. The prediction result of the classifier is used to select the robust DCT blocks to form the embedding domain. The selection information is embedded as the protocol messages into the middle-frequency coefficients of DCT blocks. To further improve the recovery possibility of the protocol message, a robustness enhancement method is proposed. It decreases the predicted non-robust possibility of the robustness classifier by modifying low-frequency coefficients of DCT blocks. The experimental results show that the proposed method has better robustness performance compared with state-of-the-art robust steganography and does not have the disadvantage regarding behavior security. The method is universal and can be implemented in different JPEG compression channels after fine-tuning the classifier. Moreover, it has better security performance compared with the state-of-the-art method when embedding large-sized secret messages.

Embedding color watermark image to color host image based on 2D-DCT

For protecting the copyright of color image, a blind watermarking algorithm for color digital images is proposed in this paper. First, affine transform and Arnold transform are successively used in the pre-processing stage to encrypt watermark information twice, which greatly improves security of watermarking algorithm. Then, the different embedding coefficients in the different image blocks and the different quantization steps in the different image layers are selected to modify part of the middle-frequency coefficients after two-dimensional discrete cosine transform (2D-DCT) for embedding the color digital watermark, which helps to improve the invisibility and robustness of watermark. Finally, the relationship between coefficient pairs of 2D-DCT is used to realize the blind extraction of the watermark information. By comparing the proposed algorithm to other relevant watermarking algorithms after many experiments, we can see that the proposed watermarking algorithm has better invisibility, stronger robustness, larger capacity and higher security.

Copyright protection scheme for color images using extended visual cryptography

Most of the existing visual cryptography based copyright protection schemes create random looking shares which can create suspicion of some secret information being shared. In order to handle this issue, a copyright protection scheme based on curvelet transform and extended visual cryptography is proposed for color images. Robustness of the scheme against various attacks is achieved by using inter-layer low and middle frequency coefficients obtained by applying discrete curvelet transform on R,G, and B components of host image. The curvelet inter-layer coefficients are used to create a master share. This master share and the watermark are used to create the ownership share by using the codebook. XOR-superimposition of master and ownership shares retrieve the watermark to prove the copyright. Security of the scheme is achieved by creating meaningful ownership shares; and by using Baker’s Map for scrambling watermark and transformed host image. The scheme is robust to withstand several image processing attacks as well as provides better imperceptibility. Effectiveness of the scheme is shown by comparing it with the existing copyright protection schemes.

New image blind watermarking method based on two-dimensional discrete cosine transform

In this paper, a new image blind watermarking method based on two-dimensional Discrete Cosine Transform (2D-DCT) is presented to realize copyright protection of color image. At first, 2D-DCT is performed on the selected image blocks, and some fixed coefficients in the middle frequency are selected as embedding position of watermark. Then, the watermark embedding and extraction procedure are completed by modifying the relationship of size between the selected middle-frequency coefficients with the proposed rules. The advantages of the presented algorithm include the following two points: 1) the relationship of size between the selected middle-frequency coefficients of 2D-DCT is used to fulfill the process of watermark embedding and extraction; 2) the presented algorithm uses color digital image as carrier image and watermark image, which is not same as most watermarking techniques. In recent years, most of the watermarking algorithms used gray or binary image as watermark. In this presented algorithm, all the digital carrier images are chosen from two public standard image databases, i.e. CVG-UGR and USC-SIPI. A series of simulation results prove that this presented algorithm not only satisfies the invisibility of watermarking algorithm, but also makes good performance of robustness, security and embedding capacity.

A novel dyadic multiresolution wavelet image steganography using N-ary

Steganography plays an important role in information sharing. In this paper a wavelet based image steganography using Haar wavelet and an N-ary notation is proposed. The high and middle frequency coefficients are selected based on the Shannon entropy value to identify the best sub band for data hiding. Peak signal to noise ratio and Structure similarity index metric values are computed from the stego image. The empirical results show the proposed method provides good, better imperceptibility and data capacity with average peak signal to noise ratio 53.60 dB for 359,112 bits in terms of effectiveness. To prove this accomplishment of the method, several experiments were conducted and compared the results with existing works.

Focus and Blurriness Measure Using Reorganized DCT Coefficients for an Autofocus Application

In this paper, two metrics for measuring image sharpness are presented and used for an autofocus (AF) application. Both measures exploit reorganized discrete cosine transform (DCT) representation. The first metric is a focus measure, which involves optimal high- and middle-frequency coefficients to evaluate relative sharpness. It is robust to noise while remaining sensitive to the best focus position. A psychometric function-based metric is introduced to quantify the focus measure. The second metric is a no-reference blurriness metric, which is used to measure absolute blurriness. It first constructs multiscale DCT edge maps using directional energy information and then determines image blurriness by combining change information in edge structures with image contrast. This metric gives predictions that are closely correlated with subjective perceived scores and shows performance comparable with that of state-of-the-art methods, especially for noisy images. For noisy situations, the two metrics are adjusted adaptively according to the estimated noise level. To prevent the introduction of extra computational load, an efficient noise-level estimation algorithm based on median absolute deviation is presented. This algorithm exploits only the available reorganized DCT coefficients. With the focus and blurriness measures, an AF method for which the two metrics play an important role was developed. Because of their high-quality performance, the realized AF function is able to locate the best focus position swiftly and reliably.

基于Slant变换的脆弱水印算法

针对图像内容的真伪和完整性难以鉴定的问题，本文提出一种基于Slant变换的脆弱水印图像认证的算法。该算法的思想是首先将原始图像进行8 × 8的分块，再对每一个分块进行Slant变换；然后利用Logistic混沌映射产生一个混沌序列，将该混沌序列与水印图像异或，得到水印信息；将水印信息嵌入到经Slant变换后的中频系数中，再进行Slant逆变换得到嵌入水印的图像。利用Slant变换，使得计算更加简单快速，增强了水印的不可见性。仿真结果表明，该算法具有良好的定位篡改能力。 For the problems of image content’s authenticity and integrity are difficult to identify, this paper proposes a fragile watermark image authentication algorithm based on Slant transform. The algo-rithm’s idea was that the size of the original image is divided into 8 × 8 block, then each block do Slant Transform operation. Then using the Logistic chaotic generates a chaotic sequence, the chaotic sequence and the watermark image do xor arithmetic, and we get the watermark information. The watermark is embedded into the Slant middle frequency coefficients, and then we get the watermarked image by doing Slant inverse transformation. The Slant transform makes calculation more simple and fast, and enhances the invisibility of the watermark. The simulation results show that the algorithm has good capability of tampering localization.

Image authentication algorithm with recovery capabilities based on neural networks in the DCT domain

In this study, the authors propose an image authentication algorithm in the DCT domain based on neural networks. The watermark is constructed from the image to be watermarked. It consists of the average value of each 8 × 8 block of the image. Each average value of a block is inserted in another supporting block sufficiently distant from the protected block to prevent simultaneous deterioration of the image and the recovery data during local image tampering. Embedding is performed in the middle frequency coefficients of the DCT transform. In addition, a neural network is trained and used later to recover tampered regions of the image. Experimental results shows that the proposed method is robust to JPEG compression and can also not only localise alterations but also recover them.

Effect of Weight Factor on The Performance of Hybrid Column Wavelet Transform used for Watermarking under Various Attacks.

Digital image watermarking is aimed at copyright protection of digital images. Strength of embedded watermark plays an important role in robustness and invisibility of watermarking technique. In this paper, effect of two parameters namely, watermark strength and middle frequency coefficients of host image used for embedding watermark is studied. In the given watermarking technique, watermark is normalized before embedding. This reduces the strength of watermark so that there will be minimum possible distortion in watermarked image. However, it has been observed in our work proposed in previous paper that, such embedment responds poorly to various image processing attacks like compression, cropping, resizing, noise addition etc. Hence in this paper, an attempt has been made to increase the strength of embedded watermark by using suitable weight factor so that robustness of watermarking technique proposed in our previous paper is further increased with small acceptable decrease in imperceptibility. Also middle frequency elements of host image selected for embedding watermark are varied by selecting different rows of host such that slowly we move from middle frequency components towards high frequency components. For certain attacks like image cropping, selection of middle frequency coefficients affects the robustness achieved. Increase in weight factor significantly improves the performance of given watermarking technique by more than 50% as proposed in our previous paper where weight factor value was 25.

An Improved Blind Color Image Watermarking using DCT in RGB Color Space

In this paper a novel blind watermarking technique for color images using DCT has been proposed. Inproposed technique cover image is decomposed into 3 planes, namely R, G, B and for watermarking B plane is selected. B plane is divided into blocks of size 8×8. DCT is applied to each 8×8 sized block and middle frequency coefficients are selected for embedding watermark. Finally binary watermark is embedded into each8×8DCT block by adjusting middle frequency coefficients DCT(4,3) and DCT(5,2). Experimental results shows that the proposed technique is imperceptible as well as robust against wide variety of attacks like Gaussian noise, Salt –pepper noise, Gaussian filter, Median filter, Histogram equalization etc and achieves average PSNR as 58.90 dB. Proposed technique does not require cover image at the time of watermark extraction then too watermark is extracted completely and better than its counterparts available. General Terms Image Processing, Digital Watermarking,Watermark Embedding, Watermark Extracting

Robust Adaptive Video Watermarking Algorithm based on Dual Transform Domains

In this paper, we propose a robust video watermarking algorithm based on dual transform domain using the adaptive quantization method. In order to increase the robustness of watermark, Particle Swarm Optimization algorithm is used for embedding watermarks. Firstly, one-level wavelet decomposition is employed for the two-dimensional carrier signal by using the characteristics of the wavelet multi-resolution analysis, and then the lowfrequency and middle-frequency coefficients are extracted. After dividing the coefficients into small blocks, discrete cosine transform is applied to each block coefficient. Then, the adaptive quantization algorithm is designed. The optimal embedding positions in the two dimensional space of the carrier signal are determined dynamically by using Particle Swarm Optimization algorithm, and the coefficients in the optimal embedding positions are also extracted. According to the characteristics of these coefficients, the optimal quantization step sizes are determined dynamically in three dimensional space. Finally, the watermark is embedded into watermarking vector adaptively by using the optimal embedding positions and optimal quantization step sizes, then the watermarked vector will be received. The experimental results show that compared with traditional watermark algorithms, the presented robust watermark algorithm not only eliminate the block effects that might arise in the transform process, but also make full use of Particle Swarm Optimization algorithm to determine the optimal embedding positions and optimal quantization step sizes of the watermark embedding algorithm. It has implemented the adaptive embedding and increased the non-sentience and robustness of the watermark. A series of attacks and comparative experiments show that the performance of the proposed algorithm is better than traditional algorithms.

Watermarking Algorithm Based on Informed Coding and Informed Embedding

Informed coding and informed embedding have received considerable attention as a method of digital watermarking with side information in resent years. We designed a new type of codes called structured dirty-paper trellis in which each message is replaced by amount of alternative vectors. This method is very efficient to prevent brightness scaling. A Viterbi decoder is used in the detecting part to find out the highest correlation path. The correct message will be detected no mater how the brightness has been changed for it has no relativity with brightness. In embedding part, watermarking message is adapted by SNR. The original image is divided into several blocks which are transformed by DCT and the adaptive parameter is calculated based on SNR for each block, then watermarking components with different strength are inserted into some middle-frequency coefficients. The experimental results demonstrate that the watermarks generated with the proposed algorithm in this paper have good imperceptibility and robustness.

Multiple Digital Watermarking Algorithm Based on DCT and Spread Spectrum

In order to improve the performance of muti-digital rights protection, a multiple watermarking algorithm based on Discrete Cosine Transform (DCT) and spread-spectrum technique is proposed. First, the host image is divided into subblock and each block is manipulated by DCT. Second, two watermarks are encrypted by Arnold scrambling. Third, the watermarks are modulated by by utilizing two kinds of strategies, and then are embedded in middle frequency coefficients of DCT domain. Experimental results show that the proposed algorithm is efficient to resist traditional signal processing attacks and has better security and robustness, higher capacity.

Digital Image Watermarking Based on Second Generation Wavelet Transform

Most of the watermarking techniques based on DWT technique embed watermarks into the detail (or middle frequency) coefficients of the host image for a good-trade-off between robustness and fidelity. But, in order to obtain the most robustness, the DC area (LL sub-band) may be a most suitable region for watermark embedding, as the signal energy of DC components is much bigger than that of high frequency sub-bands. A blind novel watermarking algorithm based on fast lifting wavelet transform, a kind of second generation wavelet transform, is proposed. Firstly, a multi-level discrete lifting wavelet transform is employed, and then the watermark is embedded into DC area of last level lifting wavelet transform according to amplitude modulation method with a secret key, lastly a watermarked image is obtained after lifting wavelet reconstruction to be applied. The results of experiments show that this algorithm is still effective after applying high compression ratio JPEG.

A Watermark Algorithm Based on DCT and M Sequence Scrambling

Image scrambling is an approach to secure the image data by scrambling the image into an unintelligible format. Based on M sequence which can be produced by a series shift registers, this paper proposes a method of scrambling 2-bit watermark image, in which the effectiveness is controlled by given private keys. The user can change the security keys to generate many different M sequences. In watermark embedding algorithm, block DCT with size of 8×8 is performed on the given image, the relationship between the selected DCT middle frequency coefficients is used to embed scrambled watermark. When extracting watermark from the watermarked image no original image is needed. The simulation results show the proposed scheme can guarantee high visual quality of watermarked image, and the same time attain a good robustness to common image processing and attacks.

The Application of Evolutionary Algorithm to Image Fusion

This paper presents a novel evolutionary algorithm to image fusion. An original image is divided into blocks with fixed size. According to the idea of the evolutionary algorithm, the image is analyzed using fractal dimension to attain its feature blocks containing edges and textures that are used in the later embedding process and used to form a feature label. The evolutionary algorithm that is the fusion of the feature label and a binary copyright symbol not only represents the copyright symbol, but also reflects the feature of the image. The evolutionary algorithm that is adaptive to the individual image is embedded into the relations between middle-frequency coefficients and corresponding DC coefficients. Experimental results show that this evolutionary algorithm can get good perceptual invisibility, adaptability and security.

An Image Authentication Scheme Based on Correlation

This paper proposes a watermarking algorithm based on correlation to authenticate image content. The original image is converted to YIQ space first, then subdivided into 8× 8 non-overlapping blocks. DCT transform is executed on each block. The watermark sequence is derived from certain low frequency coefficients. It is hided into the middle frequency DCT coefficients of another pseudo-randomly selected block with different embedding strength according to the pre-calculated correlation. The content authentication is implemented through correlation calculation between the low frequency coefficients and the corresponding middle frequency coefficients. Experiment shows that the algorithm is robust to JPEG compression, and it is sensitive to malicious tampering. Comparison with other similar watermarking algorithms in DCT domain is also taken to verify our scheme. The scheme is secure and suitable to be used in image content authentication.

Audio steganography algorithm based on lifting wavelet transform and matrix coding

With the main purpose of improving the embedding capacity and concealment,using Human Auditory System (HAS) masking properties,an audio steganography algorithm based on lifting wavelet transform and matrix coding to embed secret information was proposed. MPEG Ⅰ audio psychoacoustic model 1 was used to control embedding frames,middle and low frequency coefficients of lifting wavelet transform was choosen to host audio signal,and matrix coding which could improve embedding efficiency and decrease modified proportion was exploited to realize the secret information hiding. The simulation experimental results show that the algorithm not only has excellent concealment and embedding capacity,but also good robustness against noise addition,low pass filtering,resampling,MP3 compression and synchronization attack. Meanwhile,the method can realize blind extraction.

A novel watermarking scheme for JPEG images

Image watermarking with both insensible detection and high robustness capabilities is still a challenging problem. Even if some of the watermarking areas involve huge financial implication, there are relatively fewer efforts presented, which primarily focus the sustainability against some attacks, which are specific to financial application area particularly. One of such application area is Fingerprinting and a major threat for this area is Collusion Attack. This paper presents an inherently collusion attack resistant (ICAR) scheme for hiding a logo-based watermark in JPEG images. This scheme is based on averaging of low and middle frequency coefficients of block Discrete Cosine Transform (DCT) coefficients of an image. Experimental results show the robustness of the proposed scheme against the JPEG compression and other common image manipulations.

A GENETIC PROGRAMMING APPROACH TO DCT WATERMARKING

In this paper, a new approach for the DCT coefficients watermarking method which is commonly used frequency domain watermarking technique is studied. Least meaningful DCT coefficients blocks are specified by using genetic algorithm. The watermarks are embedded into these blocks for minimum distortions. Watermarks, which are generally embedded into middle band frequency coefficients, were embedded into least meaningful DCT coefficients. The SNR (Signal Noise to Ratio) of the proposed method is compared with the classical DCT coefficients methods. The results showing the effectiveness of the proposed method are presented.