Watermark Location Research Articles

Split then Refine: Stacked Attention-guided ResUNets for Blind Single Image Visible Watermark Removal

Digital watermark is a commonly used technique to protect the copyright of medias. Simultaneously, to increase the robustness of watermark, attacking technique, such as watermark removal, also gets the attention from the community. Previous watermark removal methods require to gain the watermark location from users or train a multi-task network to recover the background indiscriminately. However, when jointly learning, the network performs better on watermark detection than recovering the texture. Inspired by this observation and to erase the visible watermarks blindly, we propose a novel two-stage framework with a stacked attention-guided ResUNets to simulate the process of detection, removal and refinement. In the first stage, we design a multi-task network called SplitNet. It learns the basis features for three sub-tasks altogether while the task-specific features separately use multiple channel attentions. Then, with the predicted mask and coarser restored image, we design RefineNet to smooth the watermarked region with a mask-guided spatial attention. Besides network structure, the proposed algorithm also combines multiple perceptual losses for better quality both visually and numerically. We extensively evaluate our algorithm over four different datasets under various settings and the experiments show that our approach outperforms other state-of-the-art methods by a large margin.

An Effective Watermarking Method Based on Energy Averaging in Audio Signals

Methods based on discrete cosine transform (DCT) have been proposed for digital watermarking of audio signals; however, the watermark is often vulnerable to data compression and signal processing. This paper presents an effective audio watermarking method by energy averaging of DCT coefficients such that an audio signal with watermark is robust to data processing. The method is to divide an audio signal into segments by three parameters defining the segment length, the segment sequence of watermark location, and the frequency range of DCT coefficients for watermark location. An error correcting code is also integrated to improve audio signal quality after watermarking. Experimental results show that the method is robust to data compression and many other kinds of signal processing. No original signal is required for decoding the watermark. Comparison of watermarking performance with a recent work validates that the watermarking method has better audio quality and higher robustness.

Statistical Digital Watermarks of Audio Signals

Introduction. Digital watermarks (DWM) refer to embedding additional information directly into audio signal for digital right management and automatic identification of radiotelephone transmissions in aeronautical, maritime and military VHF communication. The main part. The designed embedding algorithm is based on evaluation of sliding frame to embed information or no regarding to distortions introduced by DWM. Watermark location is grounded calculation of distances norm between received and maximum likelihood estimated signal vectors in the domain of Discreet Fourier Transform and doesn’t need for any marking and synchronizing measures. Robustness of DWM against quantization, filtering, additive Gaussian noise, digital format conversion is provided by multichannel narrowband DWM transmission and application of BCH (63,30,6) error-correction code. The proposed algorithm demonstrates watermark inaudibility because of preserving signal power before and after data embedding and searching the most suitable frames for DWM positioning. Conclusion. The proposed algorithms provide advanced compromising solution of audio watermarking process: data payload – inaudibility – robustness. The designed algorithms are applicable both in analog and digital channels for transmission monitoring and digital right management.

ECG steganography using curvelet transform

Abstract ECG steganography allows secured transmission of patient data that are tagged to the ECG signals. Signal deterioration leading to loss of diagnosis information and inability to retrieve patient data fully are the major challenges with ECG steganography. In this work, an attempt has been made to use curvelet transforms which permit identifying the coefficients that store the crucial information about diagnosis. The novelty of the proposed approach is the usage of curvelet transform for ECG steganography, adaptive selection of watermark location and a new threshold selection algorithm. It is observed that when coefficients around zero are modified to embed the watermark, the signal deterioration is the least. In order to avoid overlap of watermark, an n × n sequence is used to embed the watermark. The imperceptibility of the watermark is measured using metrics such as Peak Signal to Noise Ratio, Percentage Residual Difference and Kullback-Leibler distance. The ability to extract the patient data is measured by the Bit Error Rate. Performance of the proposed approach is demonstrated on the MIT-BIH database and the results validate that coefficients around zero are ideal for watermarking to minimize deterioration and there is no loss in the data retrieved. For an increased patient data size, the cover signal deteriorates but the Bit Error Rate is zero. Therefore the proposed approach does not affect diagnosability and allows reliable steganography.

Watermark location via back-lighting modelling and verso registration

We consider the location of paper watermarks in documents that present problems such as variable paper thickness, stain and other damage. Earlier work has shown success in exploiting a computational model of backlit image acquisition --- here we enhance this approach by incorporating knowledge of surface verso features. Robustly removing recto features using established techniques, we present a registration approach that permits similarly robust removal of verso, leaving only features attributable to watermark, folds, chain lines and inconsistencies of paper manufacture. Experimental results illustrate the success of the approach.

Watermarking in E-commerce

A major challenge for E-commerce and content-based businesses is the possibility of altering identity documents or other digital data. This paper shows a watermark-based approach to protect digital identity documents against a Print-Scan (PS) attack. We propose a secure ID card authentication system based on watermarking. For authentication purposes, a user/customer is asked to upload a scanned picture of a passport or ID card through the internet to fulfill a transaction online. To provide security in online ID card submission, we need to robustly encode personal information of ID card’s holder into the card itself, and then extract the hidden information correctly in a decoder after the PS operation. The PS operation imposes several distortions, such as geometric, rotation, and histogram distortion, on the watermark location, which may cause the loss of information in the watermark. An online secure authentication system needs to first eliminate the distortion of the PS operation before decoding the hidden data. This study proposes five preprocessing blocks to remove the distortions of the PS operation: filtering, localization, binarization, undoing rotation, and cropping. Experimental results with 100 ID cards showed that the proposed online ID card authentication system has an average accuracy of 99% in detecting hidden information inside ID cards after the PS process. The innovations of this study are the implementation of an online watermark-based authentication system which uses a scanned ID card picture without any added frames around the watermark location, unlike previous systems.

Pyramid-structure-based reversible fragile watermarking

This paper presents a novel reversible fragile watermarking scheme based on a pyramidal structure. The similarities among the detail components of a pyramid-structure image are exploited to select appropriate embedding areas, and then the cryptographic watermarks are embedded into selected wavelet coefficients using a difference-expansion method. An adaptive embedding method is proposed to avoid needing extra space to store parts of the original image and the watermark location map. The cryptographic signatures are created using a watermark generation function that comprises a hashing function and a public-key encryption function. To resist counterfeiting attack, block relationships are created using toral automorphism to increase the security and implementation practicability. Experimental results show that the proposed reversible fragile watermarking scheme can successfully obtain the original image if the protected image is unaltered, and unauthorized manipulations can be correctly identified and localized even when protected images undergo a cropping attack.

Bisynchronous approach in audio watermarking based on quantization discrete wavelet transform

A bisynchronous approach was proposed for audio watermarking. The bisynchronous process consisted of self-synchronization and additive synchronization. A kind of synchronous valley was created for watermark location through five features drawn from audio carrier. Following the synchronous valleys, the additive synchronous approach was adopted to locate the usable watermarks. Meanwhile, an adaptive matching approach was stated to obtain the final watermark from several candidates. The bisynchronous algorithm was robust against most common signal processing and attacks, such as re-sampling, re-quantization, MP3 compression, echo delay, Gaussian noise corruption and cropping. It also can be against some of low pass filtering attacks.

Watermark location via back-lighting and recto removal

We consider the problem of locating a watermark in pages of archaic documents that have been both scanned and back-lit: the problem is of interest to codicologists in identifying and tracking paper materials. Commonly, documents of interest are worn or damaged, and all information is victim to very unfavourable signal-to-noise ratios—this is especially true of ‘hidden’ data such as watermarks and chain lines. We present an approach to recto removal, followed by highlighting of such ‘hidden’ data. The result is still of very low signal quality, and we also present a statistical approach to locate watermarks from a known lexicon of fragments. Results are presented from a comprehensively scanned nineteenth century copy of the Qur’ān. The approach has lent itself to immediate exploitation in improving known watermarks, and distinguishing between twin copies.