Reversible Contrast Mapping Research Articles

FPGA implementation of high-fidelity hybrid reversible watermarking algorithm

In the digitally dominated world, to enhance the data security of digital images, this paper proposes a hybrid algorithm. The algorithm enhances quality metrics and simultaneously eliminates irreversibility and underflow-overflow errors. To enhance the important evaluation parameters, PSNR and embedding bit rate, distance between neighboring pixels is reduced by employing modified enhanced normalized mean interpolation (MENMI) in the first stage. In the second stage, improved reversible contrast mapping (IRCM) provides reversibility and error elimination by contrast improvement. The robustness of the proposed algorithm against different types of attacks is also checked and verified using MATLAB. To further validate the efficiency of the proposed algorithm in terms of power, hardware resources, and simulation time, the proposed architecture has been implemented and tested on Zynq SoC FPGA platforms. The findings demonstrate that the proposed algorithm provides an average of 20% and 18% improvements in PSNR over ENMI and ENMI-HM algorithms. The hardware implementation results signify that the proposed algorithm has low timing complexity and less power consumption at high simulation frequency than existing reversible watermarking (RW) algorithms.

Heterogeneous architecture for reversible watermarking system for medical images using Integer transform based Reverse Contrast Mapping

Algorithms in multimedia security including machine learning and deep learning find its way into more and more application field resulting in strict power and area constraints. This challenges traditional homogeneous computing concepts and drives the development of new, heterogeneous architectures. One way to attain a balance of high data throughput and flexibility is to combine soft-core FPGA accelerators with CPUs as hosts. In this paper, in order to achieve higher performance, low latency, unlimited re-configurability and most important very high energy efficiency, we have proposed a hybrid architecture using CPU and FPGA. These components are then dynamically configured to form complex algorithms directly in hardware by implementing reversible watermarking of medical images. We are proposing such reversible watermarking using Integer transform based Reversible Contrast Mapping (RCM) algorithm. We got improvement in results with respect to Peak Signal to Noise Ratio (PSNR) and Structural Similarity (SSIM), when compare to the implementation in proposed architecture and simulation results of different image formats like jpeg, png and DICOM.

Efficient FPGA implementation of corrected reversible contrast mapping algorithm for video watermarking

This paper analyses and rectifies the shortcomings of reversible contrast mapping (RCM) algorithm for invisible watermarking. The proposed corrected RCM algorithm is tested by taking a gray scaled video input. The quality of services and structural similarity index matrix (SSIM) of each frame of the input video are tested in software environment. The video is obtained by OV7670 camera through Zed-board in fully field programmable gate array (FPGA) based hardware environment. FPGA devices based corrected high level synthesis of the proposed algorithm is presented. The suggested system engages pipeline structure and practices parallelism to achieve high performance. The quality of services and SSIM are also tested using FPGA devices and the comparative results with software implementations are explained. To process thirty (640 × 480) image blocks with 150 MHz clock we obtain a latency of 876.626 ns with throughput 62.328 Mbps. The critical path for single cycle is 5.992 ns. The number of resources essential is similar for watermark decoding with an improved schedule. The results acquired after implementation on Xilinx Virtex 7-XC7V2000T and programmable system-on-chip (Zynq - XC7Z030) FPGA devices confirm the practicability of real-time use with low cost and great speed.

Parallel Hardware Implementation of Efficient Embedding Bit Rate Control Based Contrast Mapping Algorithm for Reversible Invisible Watermarking

This paper presents an improved reversible contrast mapping (RCM) algorithm for reversible invisible watermarking (RIW) in both software and hardware platforms. Based on well-known parameters for RIW like distortion, embedding bit rate, payload size and data hiding capacity, an efficient embedding bit rate control based contrast mapping (EBCRCM) algorithm is proposed. An adaptive linear contrast mapping on pixel intensity value is asserted with RCM that controls the embedding bit rate without changing the embedding capacity to maintain distortion. Xilinx system generator (XSG) and VIVADO tool construct the novel VLSI architecture that needs 173.362 ns latency for 100 MHz clock with throughput 46.146 Mbps and 5.8 ns critical path for single cycle of embedding process. The proposed algorithm is verified in MATLAB tool based software platform by taking different types of multimedia data like gray-scale images, color images and video signals. Implementation of low hardware resources based VLSI architecture through zed-board in real time field programmable gate array (FPGA) platform confirms the capability of high speed, low cost and real-time use. 100% agreement is observed from software simulations and hardware platforms.

New concept of universal coding using one step reversible low contrast mapping (1RLCM)

Universal coding was developed for compressing data that the probability distribution of a symbol is unknown. Universal coding methods encode a symbol using some bits as code based on the coding algorithm. This research introduces a new concept of universal coding by encoding two symbols using Reversible Low Contrast Mapping (RLCM) transform. The proposed method transforms a pair non negative integer to a non-negative integer and a binary number. This research also introduces a compression scheme namely Average Encoding (AE) to compress a sequence of data using the proposed coding method. This method generally yields a higher compression ratio than the Elias Delta, Elias Gamma, and Fibonacci coding when it is tested using the results of differential encoding of some testing images.

Optimality in Distortion Control in Reversible Watermarking Using Genetic Algorithms

This paper proposes a reversible contrast mapping (RCM)-based reversible watermarking (RW) algorithm (RCM-RW) where optimal distortion thresholds adaptive to the image characteristics are used. A generalized form of RCM is developed using a set of transformation functions; each one may be considered as a point on a straight line, called here as operating point. Each operating point offers trade-off benefits on embedding distortion, data hiding capacity and security for the hidden data. The choice of an operating point is governed by adaptive distortion control thresholds, the values depend on the partitioning of the images on smooth, texture and edge regions. However, region-specific optimal distortion threshold is difficult to represent in closed-form expression. Genetic algorithms (GAs), due to their complex searching nature, are used here for calculating the set of distortion thresholds. Simulation results show that high embedding capacity, improved security and imperceptibility of the hidden information can be met simultaneously using a particular combination of such operating points on optimal basis. Extensive simulation results show that the proposed method outperforms the existing RW techniques.

FPGA Implementation for Modified RCM-RW on Digital Images

Reversible contrast mapping (RCM) and its various modified forms are used extensively in reversible watermarking (RW) on digital images to embed secret information. Sometimes RW demands real-time implementation that can be made by hardware realization and RCM-based RW becomes appealing due to its integer transform nature followed by least significant bit (LSB) substitution for embedding. This motivates us to propose RCM-RW on digital images with two objectives: modification on the existing RCM algorithm to increase embedding rate with low visual distortion. Later on, prototype design through field-programmable gate array (FPGA) is developed for a (256 × 256), 8-bit gray scale image using (32 × 32) image block and pipeline architecture. For a cover image of size (256 × 256), the proposed architecture requires 8,971 slices, 8,246 slice flip-flops, 9,706 numbers of four-input LUTs and 2 FIFO 16/RAMB for watermark embedding purpose. Proposed architecture consumes a power of 636[Formula: see text]mW and offers a data rate of 1.0493[Formula: see text]Mbps at an operating frequency as high as 95.3[Formula: see text]MHz.

Data Perturbation Method Based on Contrast Mapping for Reversible Privacy-preserving Data Mining

Data mining has become an important service in cloud computing. Privacy-preserving schemes must be applied to the original data before data owners provide data publicly or send the data to remote servers for mining in order to avoid improper disclosure of privacy data. Previous studies have applied data perturbation approaches to modify the content of the original data; however, this might affect the accuracy of the mining results. To solve this issue, this study develops the reversible privacy contrast mapping (RPCM) algorithm, which applies the reversible data hiding techniques used in image processing to perturb and restore data. Furthermore, to identify whether perturbed data have been modified without authorization, RPCM allows users to embed watermarks in the data. The experimental results show that the knowledge contained in the data perturbed using RPCM is similar to that in the original data. The privacy disclosure risk does not increase when the degree of data perturbation increases.

On adaptive distortion control in reversible watermarking using modified reversible contrast mapping

The use of reversible contrast mapping (RCM) on pair of pixels in images for reversible watermarking (RW) offers a flexible integer transform that leads to high embedding rate at low mathematical complexity and without requiring additional data compression. Mathematically RCM may be interpreted as a form of adaptive linear transformation on pair of pixels that controls distortion and leads to the retention of the structural information of the watermarked image. A generalized form of RCM, analogous to M-ary modulation in communication, is developed here for a set of points and their corresponding embedding spaces are shown geometrically with and without considering distortion control. Then an optimized distortion control framework adaptive to the choice of operating points is considered to improve data hiding capacity under embedding distortion constraint. Simulation results show that the combination of different M-ary approaches i.e. using the points representing the different transformation functions outperform the embedding rate, visual quality and security of the hidden information compared to the existing RCM, difference expansion (DE) and prediction error expansion (PEE) methods during over embedding. Numerical results show that an average of 13 % improvement in visual quality, 25 % improvement in security of the hidden data is achieved at 0.8 bpp embedding rate over existing PEE work. Performance in robustness against common signal processing operations, namely noise addition, smoothing filtering and some form of geometric operation like random bending attack are also studied. All these studies and the effectiveness are demonstrated with a large set of simulation results.

FPGA implementation of reversible watermarking in digital images using reversible contrast mapping

Reversible contrast mapping (RCM) and its various modified versions are used extensively in reversible watermarking (RW) to embed secret information into the digital contents. RCM based RW accomplishes a simple integer transform applied on pair of pixels and their least significant bits (LSB) are used for data embedding. It is perfectly invertible even if the LSBs of the transformed pixels are lost during data embedding. RCM offers high embedding rate at relatively low visual distortion (embedding distortion). Moreover, low computation cost and ease of hardware realization make it attractive for real-time implementation. To this aim, this paper proposes a field programmable gate array (FPGA) based very large scale integration (VLSI) architecture of RCM-RW algorithm for digital images that can serve the purpose of media authentication in real-time environment. Two architectures, one for block size (8×8) and the other one for (32×32) block are developed. The proposed architecture allows a 6-stage pipelining technique to speed up the circuit operation. For a cover image of block size (32×32), the proposed architecture requires 9881 slices, 9347 slice flip-flops, 11291 number 4-input LUTs, 3 BRAMs and a data rate of 1.0395Mbps at an operating frequency as high as 98.76MHz.

A reversible watermark scheme for 2D vector map based on reversible contrast mapping

ABSTRACTReversible watermark is suitable for the hosts with high precision requirement. However, the existed reversible watermark methods are mainly for raster images, and the reversible watermark schemes for vector graphics still have the defects such as low capacity and significant distortion. To counterstrike these situations, a reversible watermark scheme for two‐dimensional vector map based on reversible contrast mapping is proposed. First, the coordinates of the vertices are chosen according to the data precision requirements; then, the data of two‐dimensional vector maps are preprocessed to reduce distortion. After that, the encrypted watermark is embedded into the relative coordinates by using the reversible contrast mapping transform. Experimental results and analysis show that the proposed scheme can achieve higher payload, better reversibility, and invisibility than those of the existed schemes based on difference expansion, discrete cosine transform, and so on. It has great potential in the application of map data authentication and secure communication. Copyright © 2012 John Wiley & Sons, Ltd.

Reversible authentication and cross-recovery of images using ( t, n)-threshold and modified-RCM watermarking

This paper presents an image authentication scheme for digital images. The proposed scheme protects a group of n images mutually. It designs a block matching procedure to generate the recovery data for each image, and applies a ( t, n − 1), 2 ≤ t < n, threshold mechanism to encode each recovery data in n − 1 shares. The recovery shares are cross-embedded in the n images using a modified reversible contrast mapping watermarking scheme. A signature-based authentication code is finally generated and stamped to provide evidence for integrity of each image. The scheme not only can detect the tampering activities, but also can locate and recover the invalid regions of the tampered image if t or more watermarked images in the same group were intact. A nice characteristic of the proposed scheme is that the original images can be reconstructed lossless if no watermarked image was tampered, making the technique feasible in the application of protecting very sensitive images such as military or medical images. Experimental results show that the proposed scheme successfully detects various kinds of image alterations such as filtering, cropping, and replacement, and the corrupted images are properly recovered using the cross-recovery scheme.

Steganalysis of Reversible Contrast Mapping Watermarking

This letter proposes a steganalysis scheme for detecting reversible contrast mapping (RCM) watermarking. RCM watermarking involves the transformation of pixel pairs belonging to the RCM domain, which introduces artifacts into the least-significant bit (LSB). We found that the LSB histogram varies between a stego-image to the cover image, and we used this information to design a specific steganalysis method for detecting RCM watermarking and also estimating the length of the hidden message. The experimental results show that the proposed scheme successfully breaks RCM watermarking for various embedding rates and can also accurately estimate the message length.

Very Fast Watermarking by Reversible Contrast Mapping

Reversible contrast mapping (RCM) is a simple integer transform that applies to pairs of pixels. For some pairs of pixels, RCM is invertible, even if the least significant bits (LSBs) of the transformed pixels are lost. The data space occupied by the LSBs is suitable for data hiding. The embedded information bit-rates of the proposed spatial domain reversible watermarking scheme are close to the highest bit-rates reported so far. The scheme does not need additional data compression, and, in terms of mathematical complexity, it appears to be the lowest complexity one proposed up to now. A very fast lookup table implementation is proposed. Robustness against cropping can be ensured as well