The Detection for Image Spread Spectrum Watermarking Based on Self-Adaptive Wavelet Transform by DSP

When a binary fingerprinting codeword is embedded into multimedia content by using a spread-spectrum (SS) watermarking scheme, it is difficult for colluders to perform a symbol-wise attack using their codewords. As discussed in regard to SS fingerprinting schemes, averaging their copies is a cost-effective attack from the signal processing point of view. If the number of colluders is known, an optimal detector can be used against an averaging attack with added white Gaussian noise. The detector first estimates the variance of additive noise, and then calculates correlation scores using a log-likelihood-based approach. However, the number of colluders is not usually known in a real situation. In this paper, we simplify the optimal detector by making statistical approximations and using the characteristics of the parameters for generating codewords. After that, we propose an orthogonal frequency division multiplexing-based SS watermarking scheme to embed the fingerprinting codeword into multimedia content. In a realistic situation, the signal embedded as a fingerprint is in principle attenuated by lossy compression. Because the signal amplitude in a pirated codeword is attenuated, we should adaptively estimate the parameters before calculating the scores. Different from the optimal detector, the simplified detector can easily accommodate changes in signal amplitude by examining the distorted codeword extracted from a pirated copy. We evaluate the performance of the simplified detector through simulation using digital images as well as codewords.

At present, the spread spectrum (SS) sequences used in watermark include i.i.d. random sequences and the sequences used in SS communications. They appear earlier than digital watermark. Almost no researchers pay attention to whether they are really fit for watermark. In this paper, we compare the SS watermark channel and the traditional SS communication channel. We find out that their correlation property is different. Considering cropping and translation attacks, we define watermark auto- and cross-correlation and propose Loose Autocorrelation and Tight Cross-Correlation (LAC&TCC) properties for SS watermark. The LAC&TCC properties are that, whether or not synchronized, the autocorrelation is equal or close to 1 and the cross-correlation is equal or close to 0. Accordingly, the peak correlation is divided into the peak autocorrelation Ra(l) and the peak cross-correlation Rc(l). We establish the lower bound of Rc(l) and the higher bound of Ra(l), respectively. The two bounds indicate that, no matter how small the cover is reserved, the extractor can always find a threshold to distinguish auto- and cross-correlation in theory.

This paper presents an algorithm by embedding a digital watermark into an original color image. Considering the characteristics of HVS, YUV color space is employed, this algorithm presents a new adaptive digital audio watermarking based on discrete cosine transform. The result of the experiment shows that the proposed algorithm has good robustness against various image processing and attacks, good invisibility and stability.

This paper proposes an adaptive digital watermarking scheme with RBF neural networks, in which a visually recognizable binary image watermark is embedded into the DCT domain of the cover image. The watermark was encrypted by chaotic series and inserted into the middle frequency coefficients of the cover image's blocked DCT-based transform domain. In order to make the watermark stronger to resist different types of attacks, it is important to adapt the embedding maximum amount of interested watermark before the watermark becomes visible. In this paper, RBF neural networks are used to achieve maximum-strength watermark according to the frequency component feature of the cover image. Experimental results show that the proposed techniques have good imperceptibility and can survive of common image processing operations and JPEG lossy compression with high robustness.

Protection of copyright is a crucial issue in the data transmission and distribution. Considering the fact that there are different types of information available for misuse and manipulation by all the internet users it is necessary to establish the rules for copyright protection of a certain content. In this paper, special attention is given to the technical aspects of copyright protection. We took a digital image and a digital watermark into consideration. The original image has undergone a discrete wavelet transformation. Then, spread spectrum techniques were applied to the watermark. Digital watermark is then embedded into the original image. The aim of the paper is to present the comparison of results obtained using two different spread spectrum techniques in image watermarking.

In this paper, the spread spectrum watermarking in wavelet domain is optimised by using a number of techniques to make it more efficient when executed by a platform running on mobile devices. The proposed techniques can be executed efficiently and consume less computational and power resources as compared to the conventional spread spectrum-based watermarking. The proposed technique represents binary bits in the watermark using symbols, wherein each symbol represents at least 2 binary bits. A symbol is then mapped into a pseudo noise sequence and embedded in the digital image. Our analytical results show that our schemes reduce the number of operations required for watermarking by ∼50%, while our experimental results show that our schemes save about ∼59 and ∼67% in processing time and energy consumption, respectively.

The carrier of the digital watermark expands from audio signals to radio frequency (RF) signals. Unlike audio signals, RF signals, such as the watermark transmission carrier, must be correctly demodulated with the watermark signals so that the distortion of the digital carrier embedded with the watermark is associated with the change in bit error rate. Based on the spread spectrum watermarking scheme, the distortion of the digital carrier signal is redefined, and the channel capacity expression of the watermarking scheme is derived. In addition, the optimal parameters to achieve the maximal channel capacity are discussed, and the constraint relation between the channel capacity and the allowable distortion is investigated.

We describe a digital watermarking method for use in audio, image, video and multimedia data. We argue that a watermark must be placed in perceptually significant components of a signal if it is to be robust to common signal distortions and malicious attack. However, it is well known that modification of these components can lead to perceptual degradation of the signal. To avoid this, we propose to insert a watermark into the spectral components of the data using techniques analogous to spread spectrum communications, hiding a narrow band signal in a wideband channel that is the data. The watermark is difficult for an attacker to remove, even when several individuals conspire together with independently watermarked copies of the data. It is also robust to common signal and geometric distortions such as digital-to-analog and analog-to-digital conversion, resampling, quantization, dithering, compression, rotation, translation, cropping and scaling. The same digital watermarking algorithm can be applied to all three media under consideration with only minor modifications, making it especially appropriate for multimedia products. Retrieval of the watermark unambiguously identifies the owner, and the watermark can be constructed to make counterfeiting almost impossible. We present experimental results to support these claims.

In this paper, we propose a new digital watermarking algorithm named spatial unified key insertion (SUKI) for few-color images. By performing the adaptive threshold halftoning and contour shaping and modification, we can embed a binary logo into a digital image with superior JPEG compression resistance ability. The bit error rate (BER) of JPEG attack is equal to zero for all testing images with quality factor≥80. The BER is much lower than the traditional watermarking algorithms, such as spread spectrum watermarking and quantization index modulation watermarking. The payload is considerably high and there are no "salt-and-peppers" artifacts in the watermarked images. No additional color is introduced and the palette keeps unchanged after watermark embedding. The proposed algorithm can be applied to natural images with distinct boundaries by segmenting the images into different parts.

Several spread spectrum (SS) watermarking methods have been developed to optimize imperceptibility and robustness but majority of them suffer from capacity problem due to inherent limitation of spectrum spreading. Recently, a new model of optimized SS watermark system is proposed where the number of cover signal points, payload and watermark signal-to-interference ratio (WSIR) are optimized. The objective is to meet bit error rate (BER) and peak-to-average distortion (PAD) on individual watermarked signal point are to be retained within a predefined acceptable values under the constraint of a given global embedding distortion and cover size. We further modify this SS watermarking for variable embedding rate so that each host signal point allows different data hiding capacity leading to an overall improvement in payload. Genetic algorithms (GAs) is used to optimize this adaptive SS watermarking system so that better acceptable values for BER, PAD and per sample data hiding capacity can be achieved simultaneously.

In this work, we propose a new digital watermarking scheme for extremely high-resolution printing images applicable to On-Demand Publishing (ODP) system. We designed our scheme by considering the following requirements: (i) high image quality, (ii) high security, and (iii) watermark immunity (robustness). In order to attain these requirements we employ the idea of Spread Spectrum (SS) watermarking technique in our scheme and modify it to be applicable to color (CMYK) binary printing images. Simulation results verified that we could embed a watermark spreading over the entire output image as a weak energy and still keep high image quality. Also the watermark could be robustly decoded by controlling some parameters even after some possible attacks by a third party.

Recently, works are completely based on the internet, so authentication is required to protect the content of the data because owner never wants to degrade the quality of his data. Information hiding via digital watermarks for the multimedia data is the compatible way to provide the protection of data. Watermarks are imperceptible and it is predefined pattern inserting into multimedia data to protect or authenticity. The watermark indicates that data is containing a copyright or not. Many digital watermarking algorithms have been proposed in spatial and transform domain. The performance of the digital watermarking schemes is evaluated as tradeoffs between images embedded on it, robustness against attacks and embedding induced distortions. This work provides Digital image watermarking using Fractional Fourier transform via image compression for better results comparatively previous techniques of information hiding.

HVS theory plays important role in the application of digital image watermarking technique. When inserting watermarking, the visual masking feature of HVS could be fully used to design digital watermarking algorithm with good perceived performance. When extracting watermarking from the damaged image, human's visual feature could be combined to recover the damaged image so as to obtain better effect. This article combines with human visual feature to study digital watermarking technique, utilizes watermarking redundant technique to insert watermarking, extracts watermarking in line with the damage situation of watermarking, and combines with visual redundancy feature to achieve a image scrambling algorithm that is easy to recover and a recovery scheme for damaged scrambling image.

We perceive the digital watermark detection as classification problem in image processing. We classify watermarked images as positive class whilst unwatermarked images as negative class. Support Vector Machine (SVM) is used as classifier of the watermarked and unwatermarked digital images. Two watermarking schemes i.e. Cox's spread spectrum (SS) and Single Value Decomposition (SVD) are used to embed watermark into digital images. These algorithms are selected based on their different level of robustness to Stirmark attacks. The payload of the watermark used for both algorithms is consistent at certain number of bits. SVM is trained with both the watermarked and unwatermarked images. Receiver Operating Characteristics (ROC) graphs are plotted to assess the statistical detection behavior of both the correlation detector and SVM classifier. We found that straight forward application of SVM leads to generalization problem. We suggest remedies to preprocess the training data in order to achieve substantially better performance from SVM classifier than those resulting from the straightforward application of SVM. Both watermarked and unwatermarked images are attacked under Stirmark and are then tested with the correlation detectors and SVM classifier. A comparison of the ROC of the correlation detectors and SVM classifier is performed to assess the accuracy of SVM classifier relative to correlation detectors. We found that SVM classifier has higher robustness to Stirmark attacks.

In this paper, the direct-sequence spread-spectrum technique is introduced to spread watermark signal. Then by utilizing a just noticed difference threshold in spatial domain based on visual masking effect of human visual system, watermarks strength and the embedded locations can be controlled in imagae adaptively. It was shown with experiments that the digital watermark not only can guarantee the transparency, but also has good robustness to JPEG compression, median filter, sub-sampling, etc.