Copyright Protection Of Digital Images Research Articles

Scale change and rotation invariant digital image watermarking method

AbstractIn recent years attention has focused on digital image watermarking as a method for copyright protection of digital images. Since users of images make distortions such as enlarging or reducing images depending on the application, digital image watermarking which is robust to geometric distortions has been demanded. Compensation for changes in the relative position of pixels is needed in order to allow watermarking to be detected from images with geometric distortions. In this paper we propose a method that uses feature points to perform compensations and then use frequency components to embed and detect watermarks. The feature points are obtained by a Harris‐Affine detector. At first, ellipsoids around a feature point are extracted from an image, each ellipsoid normalized to a circle, and a watermark embedded into that frequency component. Geometric distortion compensation is then performed by extracting ellipsoids in the same manner during detection and normalizing the ellipsoids into circles to detect watermarks. Using feature points for the compensation eliminates the need to embed markers for original images and positioning thereby making it possible to compensate for affine distortions such as scale and rotation. Furthermore, since one elliptical embedment region is determined for each single feature point, the watermark insertion region can be correctly extracted even if detection of several feature points fails due to distortion. © 2007 Wiley Periodicals, Inc. Syst Comp Jpn, 38(10): 1– 11, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.20670

Digital image copyright protection scheme based on visual cryptography and singular value decomposition

A digital image copyright protection scheme based on visual cryptography (VC) and singular value decomposition (SVD) techniques is proposed. In the proposed scheme, a master share is first constructed by applying SVD to a host image. Then, the master share is used together with a secret image to construct an ownership share, according to a two-out-of-two VC scheme. The secret image for ownership identification can be revealed by stacking the master share, and the ownership share. The proposed scheme embeds the secret image without modifying the host image. In addition, the hidden secret image can be extracted without resorting to the original host image and the aid of computers. Experimental results show that the proposed scheme, compared with existing schemes, achieves stronger robustness against several common attacks.

Combined watermarking and fingerprinting technologies for digital image copyright protection

A combined scheme of watermarking and fingerprinting technologies for image copyright protection is proposed. Most previous watermarking algorithms embedded either a pseudorandom sequence or a visually recognizable pattern as a watermark into the original media. The present paper advocates that a practical watermarking system should combine these two types of watermarks for advanced copyright protection. First, the original image is decomposed by a three-level discrete wavelet transform. Then, a visually recognizable pattern is permuted by a key, key0. This is then expanded and embedded into one of the middle-frequency sub-bands. Next, key0 is also used to choose the random locations from the counterpart middle-frequency sub-band for constructing the fingerprint of this image. Under these circumstances, this scheme is suitable for large-scale use of watermarking aimed at simultaneous identification and transaction tracking for owners. Extensive simulation results show that the watermarked image preserves high fidelity, and the embedded watermark, together with the constructed fingerprint, could be perfectly extracted under attack-free conditions. In addition, the combined scheme is robust to common image processing operations, geometric distortion, collusion attack and composite attack.

Robust digital image watermarking based on subsampling

This paper presents a robust digital watermarking scheme for copyright protection of digital images. Four subimages are obtained from the host image by using subsampling. A binary watermark image is permutated using chaotic map and then is embedded into the DCT coefficients of two of the subimages which are selected according to a random coordinates sequence generated by a secret key. Watermark extraction is simply by comparing the DCT coefficients of the watermarked subimages and does not need original image. Experimental results show good robustness and security of the proposed scheme.

A new wavelet based logo-watermarking scheme

A new wavelet based logo-watermarking scheme for copyright protection of digital image is presented. Instead of using a noise type Gaussian sequence, a visually meaningful gray scale logo is used as watermark. Watermark embedding process is carried out by transforming both the image and logo in wavelet domain. To embed the watermark robustly and imperceptibly, watermark bits are added to the significant coefficients of each subband selected by considering the human visual system (HVS) characteristics. A scheme is developed for reliable extraction of watermark from distorted images. From the experimental results it can be observed that proposed method is robust to wide variety of attacks. Comparison with the existing methods shows the superiority of the proposed method.

Object watermarks for digital images and video

The growth of new image technologies has created a need for techniques that can be used for copyright protection of digital images and video. One approach for copyright protection is to introduce an invisible signal, known as a digital watermark, into an image or video sequence. With the development of MPEG-4, frame-based approach has been migrating to object-based approach. Therefore, object-based watermarking schemes are needed. In this article, we propose a novel blind object watermarking scheme for images and video using shape adaptive-discrete wavelet transform (SA-DWT). To make the watermark robust and perceptual invisible, we embed it in the weighting mean of the wavelet blocks using the quantisation visual model based on the human visual system. Watermark detection is accomplished without the original, unwatermarked object by using statistical detection technique. Experimental results demonstrate that the proposed watermarking scheme is perceptual invisible and robust against many attacks such as lossy image/video compression (e.g. JPEG, JPEG2000 and MPEG-4), scaling, adding noise, filtering, D/A and A/D conversion, etc.

Embedding Color Watermarks in Color Images

Robust watermarking with oblivious detection is essential to practical copyright protection of digital images. Effective exploitation of the characteristics of human visual perception to color stimuli helps to develop the watermarking scheme that fills the requirement. In this paper, an oblivious watermarking scheme that embeds color watermarks in color images is proposed. Through color gamut analysis and quantizer design, color watermarks are embedded by modifying quantization indices of color pixels without resulting in perceivable distortion. Only a small amount of information including the specification of color gamut, quantizer step-size, and color tables is required to extract the watermark. Experimental results show that the proposed watermarking scheme is computationally simple and quite robust in face of various attacks such as cropping, low-pass filtering, white-noise addition, scaling, and JPEG compression with high compression ratios.

A Watermarking Scheme Based on Principal Component Analysis Technique

In this paper, we shall propose a new method for the copyright protection of digital images. To embed the watermark, our new method partitions the original image into blocks and uses the PCA function to project these blocks onto a linear subspace. There is a watermark table, which is computed from projection points, kept in our new method. When extracting a watermark, our method projects the blocks of the modified image by using the PCA function. Both the newly projected points and the watermark table are used to reconstruct the watermark. In our experiments, we have tested our scheme to see how it works on original images modified by JPEG lossy compression, blurring, cropping, rotating and sharpening, and the experimental results show that our method is very robust and indeed workable.

Robust template matching for affine resistant image watermarks

Digital watermarks have been proposed as a method for discouraging illicit copying and distribution of copyrighted material. This paper describes a method for the secure and robust copyright protection of digital images. We present an approach for embedding a digital watermark into an image using the Fourier transform. To this watermark is added a template in the Fourier transform domain to render the method robust against general linear transformations. We detail a new algorithm based on polar maps for the accurate and efficient recovery of the template in an image which has undergone a general affine transformation. We also present results which demonstrate the robustness of the method against some common image processing operations such as compression, rotation, scaling, and aspect ratio changes.

An iterative template matching algorithm using the Chirp-Z transform for digital image watermarking

Digital watermarks have been proposed as a method for discouraging illicit copying and distribution of copyrighted material. This paper describes a method for the secure and robust copyright protection of digital images. The key contribution lies in the development of a fast iterative template matching algorithm based on log-log or log-polar maps. The algorithm exploits the properties of the Chirp-Z transform to obtain the accuracy needed in the detection of transformations in realistic watermarking applications. Test results verify the robustness of the method.

Cryptographic copyright protection for digital images based on watermarking techniques

In this paper we present a new approach for the secure and robust copyright protection of digital images. We describe a system for generating digital watermarks and for trading watermarked images. The system is based on a new watermarking technique, which is robust against image transformation techniques such as compression, rotation, translation, scaling and cropping. It uses modulation of the magnitude components in Fourier space to embed a watermark and an accompanying template and, during watermark extraction, reads a template in the log polar transform of the frequency domain. The template is used for analyzing scaling and rotation suffered by the watermarked stego-image. The detection of the watermarks is also possible without any need for the original cover-image. In addition, the system applies asymmetric cryptographic protocols for different purposes, namely embedding/detecting the watermark and transferring watermarked data. The public key technique is applied for the construction of a one-way watermark embedding and the verification function to identify and prove the uniqueness of the watermark. Legal dispute resolution is supported for the multiple watermarking of a digital image without revealing the confidential keying information.

Perceptual watermarks for digital images and video

The growth of new imaging technologies has created a need for techniques that can be used for copyright protection of digital images and video. One approach for copyright protection is to introduce an invisible signal, known as a digital watermark, into an image or video sequence. In this paper, we describe digital watermarking techniques, known as perceptually based watermarks, that are designed to exploit aspects of the the human visual system in order to provide a transparent (invisible), yet robust watermark. In the most general sense, any watermarking technique that attempts to incorporate an invisible mark into an image is perceptually based. However, in order to provide transparency and robustness to attack, two conflicting requirements from a signal processing perspective, more sophisticated use of perceptual information in the watermarking process is required. We describe watermarking techniques ranging from simple schemes which incorporate common-sense rules in using perceptual information in the watermarking process, to more elaborate schemes which adapt to local image characteristics based on more formal perceptual models. This review is not meant to be exhaustive; its aim is to provide the reader with an understanding of how the techniques have been evolving as the requirements and applications become better defined.

A watermarking technique based on one-way hash functions

Digital watermarking techniques have been proposed for the copyright protection of digital images. A digital watermarking technique is a technique for embedding invisible watermarks in a digital image. The watermarks must be designed to be unrecognizable by unauthorized people and to be identified by the legal copyright owner of the image. In this paper, we proposed a new copyright watermarking scheme. Our scheme is based on one-way hash functions, which are widely used in cryptosystems. The main goal of our method is to design a secure watermarking scheme.

Digital image watermarking using mixing systems

This paper presents a watermarking scheme for copyright protection of digital images. A binary logo is the copyright label which is embedded in grayscale or color digital images. A set of integer parameters, selected by the legal owner, controls the watermarking algorithm via a strongly chaotic (mixing) system. Watermark detection is performed without resorting to the original image. The embedded binary logo is reconstructed or the statistical detection certainty is provided indicating the watermark existence. Numerical experiments testify the efficiency of a particular watermarkingalgorithm as a reliable verification tool for proving copyright ownership of the digital image.

Copyright protection of digital images by embedded unperceivable marks

Digital watermarking has been proposed as a solution to the problem of copyright protection of multimedia documents in a networked environment. It makes it possible to tightly associate a code to an image, allowing the identification of the data creator, owner and so on. In this paper, after a review of some important watermarking techniques, a new watermarking algorithm for digital images is presented: the method, which enhances a previous technique proposed by Cox et al. [1] [I.J. Cox, J. Kilian, T. Leighton, T. Shamoon, Secure spread spectrum watermarking for multimedia, NEC Research Institute Technical Report 95-10], operates in the frequency domain, by embedding in a selected set of DCT coefficients a sequence of randomly generated real numbers. By exploiting their statistical characteristics, it is possible to reliably extract the embedded sequences without resorting to the original unmarked image. Experimental results demonstrate that the watermark is robust to several image transformations.