An image watermarking scheme using HVS characteristics and spread transform

Steganography algorithms used to secure sensitive data on the Internet. It hides the secret data in the cover image and provides imperceptibility to the attacker. The least significant bit (LSB) is the most preferred data hiding technique in the steganography. In this technique, the least significant bit of the cover image pixel replaced with data bits. In the literature, the data hiding achieved without considering the human visual system (HVS) characteristics that degrade the visual quality of the image. In this paper, the optimized data hiding has done while considering the HVS characteristics. The colour image contains three planes known as the red–green–blue plane. The green plane is the most sensitive, and blue is less sensitive to the human eyes. Thus, in the proposed technique, the green plane used as a reference plane for data hiding in the red and blue planes. In the optimized data hiding technique, the secret data bits match with the cover pixel bits. If the bits match, then the corresponding optimal index determines, else data hiding done in the LSB bits of the cover pixel. After that, the optimal indexes hide in the cover image using a 2-bit LSB technique. In the proposed technique, image smooth and edge region characteristics explored before data hiding. There is a high correlation between the consecutive pixels in the smooth region and the minimum correlation on the edges. Thus, we have matched the secret data bits with the cover pixel bits in the smooth region and hide the optimal indexes on the edges. The experimental results performed on the standard dataset images downloaded from the USC-SIPI image database. The experimental results show that the proposed technique provides better visual quality as compared to the existing techniques.

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.

The ambiguity attack is to derive a valid watermark from a medium to defeat the ownership claim of the real owner. Most of the research suggests that it is difficult to design a provably secure non-ambiguity watermarking without a trusted third party. Recently, Li and Chang have provided a specific blind additive spread spectrum watermarking scheme as an example that is provably non-ambiguous. However, the proposed watermarking needs the length of watermark n > 3.07 × 10 9 according to our analysis. In this paper, a framework for quantization based watermarking schemes and non-blind spread spectrum watermarking scheme to achieve non-ambiguity is proposed. As a result, many of the existent watermarking schemes can achieve provable non-invertibility via using this framework, and an nonambiguity ownership verification protocol without a trusted third party may be constructed. We have obtained the close form solution of false positive rate for the underlying quantization based schemes and spread spectrum watermarking schemes (both blind and non-blind). The length of key of pseudo-random sequence generator (PRSG) is extended to m = c × n , the cardinality of the valid watermark set is extended to vWv = 2 m = 2 c,n , thus leading to more security to exhaustive searching attack than the Li and Chang's scheme, which has m = sn. In addition, the required length of watermark becomes much shorter than that required in the Li and Chang's scheme. At last, we propose a noninvertible and robust quantization-based watermarking scheme with the length of watermark being n=1024 .

A blind robust digital image watermarking scheme using chaotic encryption and HVS in DWT domain is presented. Firstly, the original image is transformed into some sub-band coefficients using discrete wavelet transformation (DWT), and then the binary image watermark signal is encrypted using logistic chaos map before it is embedded. Taking into account the characteristics of human visual system (HVS), the watermark is embedded into the important sub-band coefficients. Because of the multi-resolution decomposition for DWT and meaningful HVS, the proposed scheme can achieve good robustness, which is demonstrated in the following experiments.

Non-linear polynomial filters for edge enhancement of mammogram lesions

These days, researchers have used many techniques in e-multimedia data for intellectual property protection. One of these important techniques is watermarking which is superior to Digital Signature because it does not rise overhead and it can prevent unauthorized users from misusing digital information. However, the number of attacks with aim of distorting watermark signal or disturbing watermarks detecting are exploding. Consequently, the watermark techniques have became more complicated, but still they are not fully robust against some geometric distortions. To overcome this issue and to be enough robust against the malicious attacks, and provide a high level of imperceptibility,the watermark schemes have discovered and developed the advantages by means of Singular-value decomposition. Therefore, in recent decades there has been a significant increasing in using of SVD domain in many new image watermarking schemes, which show high robustness and imperceptibility. This discussion of SVD in image watermarking schemes included: a concise overview on watermarking systems, a brief review on SVD properties in image processing and its weaknesses, the concept of SVD components, the main classification of different SVD based image-watermarking schemes; a brief summary of various secure SVD-based watermarking techniques and all major SVD coefficients modifying strategies are presented. In addition, potential issues and some existing solutions and guidelines are provided. Furthermore, the performance comparisons of the discussed techniques are presented in tabular format. This article contribution provides essential and potential information for the researchers to design, develop and implement efficient robust and hybrid SVD-based image watermarking systems.

In this paper, we proposed a novel watermarking scheme based on adaptive quantization index modulation and singular value decomposition in the hybrid discrete wavelet transform (DWT) and discrete cosine transform (DCT). The secret watermark bits are embedded on the singular values vector of blocks within low frequency subband in host image hybrid DWT-DCT domain. To embed watermark imperceptibly, robustly and securely, we model the adaptive quantization steps by utilizing human visual system (HVS) characteristics and particle swarm optimization (PSO) algorithm. Experimental results demonstrate that the proposed scheme is robust to variety of image processing attacks. In the proposed algorithm the quantized embedding strategy is adopted, so no host image is needed for blind extraction of watermarking image.

This paper proposes a novel digital watermarking technique based on neural networks in wavelet domain. Watermark embed processing is carried out by transforming the host image in wavelet domain. Watermark bits are added to the significant coefficients of wavelet selected by considering the human visual system (HVS) characteristics. Because of the learning and adaptive capabilities of neural networks, the trained neural networks can exactly recover the watermark from the watermarked image. Extensive experiments show that our technique possesses significant robustness to be against the various attacks.

The human visual system is very complicate and able to handle a voluminous amount of visual information. It is composed of a receiver with a pre-processing stage, the eye and the retina, a transmission channel, the optic nerve, and a processing engine, the visual cortex. Though one has attempted to understand and model the human visual system process a stimulus is progressed through its huge neural network has not well known because of our lack of knowledge about brain behavior. As well known, the discrete wavelet transform is widely used in signal processing applications such as signal analysis, de-noising, compression etc. It has also played a key role in the field of digital image and/or audio watermarking. A general metric to measure perceptible transparency is peak signal to signal ratio which is the ratio between the maximum possible power of a signal and the power of error that affects the fidelity of its representation. But peak signal to noise ratio does not consider the characteristics of human visual system. In this paper we proposed new metric to measure the invisibility of discrete wavelet transform domain watermarked image based on human visual system using 2- dimensional contrast sensitivity function. The proposed metric was applied to a spread spectrum image watermarking scheme in discrete wavelet transform domain and evaluated by the Minkowski pooling. The experimental results were compared with peak signal to noise ratio.KeywordsImperceptibility metricDigital image watermarkingDWT domainHuman visual systemContrast sensitivity function

Liquid crystal displays (LCDs) have appeared in applications ranging from medical equipment to automobiles, gas pumps, laptops, and handheld portable computers. These display components present a cascaded energy attenuator to the battery of the handheld device which is responsible for about half of the energy drain at maximum display intensity. As such, the display components become the main focus of every effort for maximization of embedded system's battery lifetime. This paper proposes an approach for pixel transformation of the displayed image to increase the potential energy saving of the backlight scaling method. The proposed approach takes advantage of human visual system (HVS) characteristics and tries to minimize distortion between the perceived brightness values of the individual pixels in the original image and those of the backlight-scaled image. This is in contrast to previous backlight scaling approaches which simply match the luminance values of the individual pixels in the original and backlight-scaled images. Furthermore, this paper proposes a temporally-aware backlight scaling technique for video streams. The goal is to maximize energy saving in the display system by means of dynamic backlight dimming subject to a video distortion tolerance. The video distortion comprises of: 1) an intra-frame (spatial) distortion component due to frame-sensitive backlight scaling and transmittance function tuning and 2) an inter-frame (temporal) distortion component due to large-step backlight dimming across frames modulated by the psychophysical characteristics of the human visual system. The proposed backlight scaling technique is capable of efficiently computing the flickering effect online and subsequently using a measure of the temporal distortion to appropriately adjust the slack on the intra-frame spatial distortion, thereby, achieving a good balance between the two sources of distortion while maximizing the backlight dimming-driven energy saving in the display system and meeting an overall video quality figure of merit. The proposed dynamic backlight scaling approach is amenable to highly efficient hardware realization and has been implemented on the Apollo Testbed II. Actual current measurements demonstrate the effectiveness of proposed technique compared to the previous backlight dimming techniques, which have ignored the temporal distortion effect

This paper presents a new approach for the certificate verification based on digital watermarking. An invisible watermark is embedded in the owner digital photo of the certificate with different strength according to the characteristics of Human Vision System (HVS). During verification the owner photo is scanned, the watermark extracted from the scanned photo is compared with the original watermark. Several techniques are used to detect and invert geometric transformations of the watermarked images undergone by the printed and scanned process so that the embedded watermark can be successfully determined. Experiment results have demonstrated the feasibility of the proposed approach that has the advantages of high security, high flexibility and low cost.

Blind quality assessment for tone-mapped images based on local and global features

Objective image quality assessment (IQA) models have been developed by effective features to imitate the characteristics of human visual system (HVS). Actually, HVS is extremely sensitive to color degradation and complex texture changes. In this paper, we firstly reveal that many existing full reference image quality assessment (FR-IQA) methods can hardly measure the image quality with contrast and masking texture changes. To solve this problem, considering texture masking effect, we proposed a novel FR-IQA method, called Texture and Color Quality Index (TCQI). The proposed method considers both in the masking effect texture and color visual perceptual threshold, which adopts three kinds of features to reflect masking texture, color difference and structural information. Furthermore, random forest (RF) is used to address the drawbacks of existing pooling technologies. Compared with other traditional learning-based tools (support vector regression and neural network), RF can achieve the better prediction performance. Experiments conducted on five large-scale databases demonstrate that our approach is highly consistent with subjective perception, outperforms twelve the state-of-the-art IQA models in terms of prediction accuracy and keeps a moderate computational complexity. The cross database validation also validates our approach achieves the ability to maintain high robustness.

In this paper, we present a new blind video quality assessment metric considering the characteristics of human visual system (HVS). HVS indicates that internal generative mechanism (IGM) actively predicts the visual scene (predicted information) and avoid the residual uncertainty (uncertain information). Based on spatio-temporal internal generative mechanism (ST-IGM), we employ a spatio-temporal autoregressive (AR) prediction model to disassemble the video content into the predicted part and the uncertain part. Then, we separately evaluate their quality degradations by natural video statistics (NVS) model based blind VQA method. According to the perception of distortions in two parts, different weights are assigned to yield the overall quality. The experimental results demonstrate that the proposed algorithm performs much better than the state-of-the-art blind train-free algorithm on the LIVE VQA database and shows competitive performance with the existing train-based methods.

DWT-SVD digital watermarking scheme which is based on the combination of Discrete Wavelet Transform and Singular Value Decomposition is a recent digital watermarking technique and has become popular due to its robustness against various attacks. In this paper, we present an image watermarking scheme which combines previous DWT-SVD based methods which guarantees robustness without increasing algorithm complexity. In order to tackle the common drawback of existing DWT-SVD watermarking scheme, we also introduce a "reverse embedding' technique and use scaled singular values. Because our proposed method combines the strength of previous methods, it is able to provide a comprehensive and much improved robustness against various kinds of attack and this is shown in the simulations. The reverse embedding technique also avoids negative film effect which is common in existing DWT-SVD image watermarking scheme.