Showing papers on "Digital watermarking published in 1996"

Digital watermarks for audio signals

Abstract: In this paper, we present a novel technique for embedding digital "watermarks" into digital audio signals. Watermarking is a technique used to label digital media by hiding copyright or other information into the underlying data. The watermark must be imperceptible and should be robust to attacks and other types of distortion. In addition, the watermark also should be undetectable by all users except the author of the piece. In our method, the watermark is generated by filtering a PN-sequence with a filter that approximates the frequency masking characteristics of the human auditory system (HAS). It is then weighted in the time domain to account for temporal masking. We discuss the detection of the watermark and assess the robustness of our watermarking approach to attacks and various signal manipulations.

A robust content based digital signature for image authentication

Abstract: A methodology for designing content based digital signatures which can be used to authenticate images is presented. A continuous measure of authenticity is presented which forms the basis of this methodology. Using this methodology signature systems can be designed which allow certain types of image modification (e.g. lossy compression) but which prevent other types of manipulation. Some experience with content based signatures is also presented. The idea of signature based authentication is extended to video, and a system to generate signatures for video sequences is presented. This signature also allows smaller segments of the secured video to be verified as unmanipulated.

Secure spread spectrum watermarking for images, audio and video

Abstract: 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.

A watermark for digital images

Abstract: The growth of networked multimedia systems has magnified the need for image copyright protection. One approach used to address this problem is to add an invisible structure to an image that can be used to seal or mark it. These structures are known as digital watermarks. We describe two techniques for the invisible marking of images. We analyze the robustness of the watermarks with respect to linear and nonlinear filtering, and JPEG compression. The results show that our watermarks detect all but the most minute changes to the image.

A Secure, Robust Watermark for Multimedia

Abstract: 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 sprectrum 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, and requantization, including dithering and recompression and 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. Experimental results are presented to support these claims.

Watermarking digital images for copyright protection

Abstract: A watermark is an invisible mark placed on an image that is designed to identify both the source of an image as well as its intended recipient. The authors present an overview of watermarking techniques and demonstrate a solution to one of the key problems in image watermarking, namely how to hide robust invisible labels inside grey scale or colour digital images.

Transparent robust image watermarking

Abstract: We propose a watermarking scheme to hide copyright information in an image. The scheme employs visual masking to guarantee that the embedded watermark is invisible and to maximize the robustness of the hidden data. The watermark is constructed for arbitrary image blocks by filtering a pseudo-noise sequence (author id) with a filter that approximates the frequency masking characteristics of the visual system. The noise-like watermark is statistically invisible to deter unauthorized removal. Experimental results show that the watermark is robust to several distortions including white and colored noises, JPEG coding at different qualities, and cropping.

Phase watermarking of digital images

Abstract: A watermark is an invisible mark placed on an image that can be detected when the image is compared with the original. This mark is designed to identify both the source of an image as well as its intended recipient. The mark should be tolerant to reasonable quality lossy compression of the image using transform coding or vector quantization. Standard image processing operations such as low pass filtering, cropping, translation and rescaling should not remove the mark. Spread spectrum communication techniques and matrix transformations can be used together to design watermarks that are robust to tampering and are visually imperceptible. This paper discusses techniques for embedding such marks in grey scale digital images. It also proposes a novel phase based method of conveying the watermark information. In addition, the use of optimal detectors for watermark identification is also proposed.

Watermarking process resilient to collusion attacks

Abstract: A watermarking procedure wherein each of a set of copies of the work has a slightly-modified form of a "baseline" watermark that is placed within a critical region of the data. The slight variations in the watermarks, however, are not perceptually visible and do not interfere with the work. If multiple persons collude to attempt to create an "illicit" copy of the work (i.e., a copy without a watermark), however, at least one of the modified watermarks is present in the copy, thereby identifying both the illicit copy and the copier.

Watermarking method and apparatus for compressed digital video

Abstract: A digital watermarking method and apparatus allows for the watermarking of a digital video signal in a compressed form, thereby allowing watermarking of a pre-compressed video sequence without requiring the decoding and re-coding of the signal. The watermark signal is a sequence of information bits which has been modulated by a pseudo-random noise sequence to spread it in the frequency domain. The video signal is transform coded, preferably with a discrete cosine transform, and a watermark signal, which has been transform coded using the same type of transform, is added to the coded video signal. The system also includes bitstream control to prevent an increase in the bit rate of the video signal. This allows the system to be used with transmission channels having strict bit rate constraints. For each transform coefficient of the video signal, the number of bits necessary to encode the watermarked coefficient is compared to the number of bits necessary to encode the unwatermarked coefficient. If more bits are required to transmit a watermarked coefficient than to transmit the corresponding unwatermarked coefficient, the watermarked coefficient is not output, and the unwatermarked coefficient is output in its place. When watermarking interframe coded data, a drift compensation signal may be used to compensate for the accumulating variations in the decoded video signal stored at the receiver. The system may also include an encryption/decryption capability, with the watermarking apparatus located at either the transmitting or receiving end of the transmission channel.

Image watermarking using DCT domain constraints

Abstract: Watermarking algorithms are used for image copyright protection. The algorithms proposed select certain blocks in the image based on a Gaussian network classifier. The pixel values of the selected blocks are modified such that their discrete cosine transform (DCT) coefficients fulfil a constraint imposed by the watermark code. Two different constraints are considered. The first approach consists of embedding a linear constraint among selected DCT coefficients and the second one defines circular detection regions in the DCT domain. A rule for generating the DCT parameters of distinct watermarks is provided. The watermarks embedded by the proposed algorithms are resistant to JPEG compression.

Digital watermarking using stochastic screen patterns

Abstract: A method for generating watermarks in a digitally reproducible document which are substantially invisible when viewed including the steps of: (1) producing a first stochastic screen pattern suitable for reproducing a gray image on a document; (2) deriving at least one stochastic screen description that is related to said first pattern; (3) producing a document containing the first stochastic screen; (4) producing a second document containing one or more of the stochastic screens in combination, whereby upon placing the first and second document in superposition relationship to allow viewing of both documents together, correlation between the first stochastic pattern on each document occurs everywhere within the documents where the first screen is used, and correlation does not occur where the area where the derived stochastic screens occur and the image placed therein using the derived stochastic screens becomes visible.

Method for human-assisted random key generation and application for digital watermark system

Abstract: A method for the human-assisted generation and application of pseudo-random keys for the purpose of encoding and decoding digital watermarks to and from a digitized data stream. A pseudo-random key and key application "envelope" are generated and stored using guideline parameters input by a human engineer interacting with a graphical representation of the digitized data stream. Key "envelope" information is permanently associated with the pseudo-random binary string comprising the key. Key and "envelope" information are then applied in a digital watermark system to the encoding and decoding of digital watermarks. The invention includes improvements to the methods of encoding and decoding digital watermarks. Improvements are: separation of the encoder from the decoder, increased information capacity relative to spread spectrum methods, destruction of content resulting from attempts to erase watermarks, detection of presence of watermarks without ability to access watermark information, multi-channel watermark capability, use of various classes of keys for watermark access control, support for alternative encoding, decoding, or other component algorithms, use of digital notary to authenticate and time stamp watermark certificates.

Applications of toral automorphisms in image watermarking

Abstract: Digital watermarking methods have been proposed for various purposes and especially for copyright protection of multimedia data. The digital watermark is embedded in a digital signal or an image and must be unrecognizable by unauthorized persons and detectable only by the legal copyright owner. We use toral automorphisms as chaotic 2-D integer vector generators in order to manipulate digital image watermarking. We propose also an embedding algorithm which provides robustness under filtering and compression.

Protecting ownership rights through digital watermarking

Abstract: The Internet revolution is now in full swing, and commercial interests abound. As with other maturing media technologies, the focus is moving from technology to content, as commercial vendors and developers try to use network technology to deliver media products for profit. This shift inevitably raises questions about how to protect ownership rights. Digital watermarking has been proposed as a way to identify the source, creator, owner, distributor, or authorized consumer of a document or image. Its objective is to permanently and unalterably mark the image so that the credit or assignment is beyond dispute. In the event of illicit use, the watermark would facilitate the claim of ownership, the receipt of copyright revenues, or successful prosecution. Watermarking has also been proposed for tracing images that have been illicitly redistributed. In the past, the infeasibility of large-scale photocopying and distribution often limited copyright infringement, but modern digital networks make large-scale dissemination simple and inexpensive. Digital watermarking allows each image to be uniquely marked for every buyer. If that buyer makes an illicit copy, the copy itself identifies the buyer as the source.

Protecting publicly available images with a visible image watermark

Abstract: In some cases, it is desired to produce images that are suitable for one application and unsuitable for others. With the 'Vatican Library Accessible Worldwide' and 'Luther Digital' projects, for example, it was desired to make available through the Internet images of Vatican Library and Luther Library manuscripts that are suitable for scholarly study yet are unsuitable as a source for unapproved publication. One of the techniques used to accomplish this is the visible image watermark. Our technical goals for watermarking include (1) applying a readily visible mark to the image that clearly identifies its ownership, (2) permitting all image detail to be visible through the watermark, and (3) making the watermark difficult to remove. In this paper, we describe the technique we use. We also discuss the characteristics of good watermarks and options we have used in their application. illustrative watermarked images are presented.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Marking a digitally encoded video and/or audio signal

Abstract: An electronic watermarking scheme is proposed that can significantly increase the security of copy protection mechanisms. The watermarking methods works at high level in the hierarchy of the (MPEG) source signal. This ensures that the watermark is easily detectable, but difficult to erase without significant transcoding effort. Such transcoding is considered a difficult and expensive task that may furthermore lead to loss of quality or increase in bit rate.

Watermarking of image data using MPEG/JPEG coefficients

Abstract: A watermark is embedded into video/image/multimedia data using spread spectrum methodology. The watermark is extracted from watermarked data without the use of an original or unwatermarked version of the data by using MPEG/JPEG coefficients. The image to be watermarked is divided into subimages. Each subimage is embedded with a watermark. When extracting the watermark, the result from each subimage is combined to determine the originally embedded watermark.

A secure, imperceptible yet perceptually salient, spread spectrum watermark for multimedia

Abstract: 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 a 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 water-marked 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, and requantization, including dithering and recompression and 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. Experimental results are presented to support these claims.

Method and system for inserting a spread spectrum watermark into multimedia data

Abstract: Digital watermarking of audio, image, video or multimedia data is achieved by inserting the watermark into the perceptually significant components of a decomposition of the data in a manner so as to be visually imperceptible. In a preferred method, a frequency spectral image of the data, preferably a Fourier transform of the data, is obtained. A watermark is inserted into perceptually significant components of the frequency spectral image. The resultant watermarked spectral image is subjected to an inverse transform to produce watermarked data. The watermark is extracted from watermarked data by first comparing the watermarked data with the original data to obtain an extracted watermark. Then, the original watermark, original data and the extracted watermark are compared to generate a watermark which is analyzed for authenticity of the watermark.

Image watermarking-a spread spectrum application

Abstract: This paper discusses the feasibility of coding a robust, undetectable, digital watermark on a standard 512*512 intensity image with an 24 bit RGB format. The watermark is capable of carrying such information as authentication or authorisation codes, or a legend essential for image interpretation. This capability is envisaged to find application in image tagging, copyright enforcement, counterfeit protection, and controlled access. The method chosen is based on linear addition of the watermark to the image data. The patterns adopted to carry the watermark are adaptations of m-sequences in one and two dimensions. The recovery process is based on correlation, just as in standard spread spectrum receivers. The technique is quite successful for one dimensional encoding with binary patterns, as shown for a variety of gray scale test images. A discussion of extensions of the method to two dimensions, RGB format and non-binary alphabets is presented. A critical review of other watermarking techniques is included.

Watermarking Document Images with Bounding Box Expansion

Abstract: Imperceptible displacements of text objects has been shown to be a successful technique for hiding data in document images. In this paper we extend our earlier work to show how the height of a bounding box enclosing a group of text words can be used to increase the density of information hidden on a page. We present experimental results which show that bounding box expansions as small as 1/300 inch can be reliably detected, even after the distortions introduced by noisy image reproduction devices such as plain paper copiers. Digital watermarks based on this technique can be used with electronically disseminated documents for applications including copyright protection, authentication, and tagging.

Using fractal compression scheme to embed a digital signature into an image

Abstract: With the increase in the number of digital networks and recording devices, digital images appear to be amaterial, especially still images, whose ownership is widely threatened due to the availability of simple,rapid and perfect duplication and distribution means. It is in this context that several European projects aredevoted to finding a technical solution which, as it applies to still images, introduces a code or Watermarkinto the image data itself. This Watermark should not only allow one to determine the owner of the image,but also respect its quality and be difficult to remove. An additional requirement is that the code should beretrievable by the only mean of the protected information. In this paper, we propose a new scheme basedon fractal coding and decoding. In general terms, a fractal coder exploits the spatial redundancy within theimage by establishing a relationship between its different parts. We describe a way to use this relationshipas a means of embedding a Watermark. Tests have been performed in order to measure the robustness ofthe technique against JPEG conversion and low pass filtering. In both cases, very promising results havebeen obtained.Keywords: digital signature, watermarking, image, copyright protection, security, fractal compression, IFS(Iterated Function Systems), FVT (Fractal Vector

Digital watermarking of images

Abstract: In this exercise, we will study the digital watermarking of images. The exercise is categorized in different sections where various basic watermarking techniques are introduced. A necessary prerequisite for this exercise is some basic course in digital image processing. After finishing the exercise, return by email your well-commented MATLAB functions and written report. In your report, you should describe what you have done, give answers to the predefined questions (1-8), and give some comments about the exercise. Answers to the questions can (and should) be deduced without any references. The written report should resemble more of an essay than just a discrete list of answers to the questions. Remember also to include your name(s), student number(s) and email address(es) to the report. It is recommended that the report is returned in pdf format. NOTE: All required functions (tasks 1-5) should be implemented using MATLAB as separate m-files. Input parameters for the functions are specified separately for each of the tasks, but in general, the required input images must be matrices, not names of the image files. Each of the functions must have one output parameter: the result of the current task.

Digital video copy protection system

Abstract: A formatting apparatus authenticates an information signal prior to mass duplication of the signal by analyzing the signal to detect the presence or absence of a security signal therein, inserting a security signal into the information signal, and recording the modified signal only if no security signal was detected.

Data embedding method

Abstract: Data embedding is a new steganographic method for combining digital information sets. This paper describes the data embedding method and gives examples of its application using software written in the C-programming language. Sandford and Handel produced a computer program (BMPEMBED, Ver. 1.51 written for IBM PC/AT or compatible, MS/DOS Ver. 3.3 or later) that implements data embedding in an application for digital imagery. Information is embedded into, and extracted from, Truecolor or color-pallet images in MicrosoftTM bitmap (BMP) format. Hiding data in the noise component of a host, by means of an algorithm that modifies or replaces the noise bits, is termed `steganography.' Data embedding differs markedly from conventional steganography, because it uses the noise component of the host to insert information with few or no modifications to the host data values or their statistical properties. Consequently, the entropy of the host data is affected little by using data embedding to add information. The data embedding method applies to host data compressed with transform, or `lossy' compression algorithms, as for example ones based on discrete cosine transform and wavelet functions. Analysis of the host noise generates a key required for embedding and extracting the auxiliary data from the combined data. The key is stored easily in the combined data. Images without the key cannot be processed to extract the embedded information. To provide security for the embedded data, one can remove the key from the combined data and manage it separately. The image key can be encrypted and stored in the combined data or transmitted separately as a ciphertext much smaller in size than the embedded data. The key size is typically ten to one-hundred bytes, and it is derived from the original host data by an analysis algorithm.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Archival and retrieval of historical watermark images

Abstract: This project concerns the management of a multimedia database (text and image) of historical papers representing ancient watermarks. The current database contains roughly 3000 images of such watermarks; the system allows archival and retrieval by means of textual or morphological criteria. During the archival phase, textual description are stored, as well as descriptive primitives extracted together with the watermark itself by image analysis methods. For the retrieval phase, several types of queries are supported; they allow textual search on the basis of the accompanying descriptions, morphological search according to global characteristics, and shape based search on the basis of the watermark shape.

Information Hiding: First International Workshop, Cambridge, U.K., May 30 - June 1, 1996. Proceedings

Abstract: The history of steganography.- Computer based steganography: How it works and why therefore any restrictions on cryptography are nonsense, at best.- Hiding data in the OSI network model.- Stretching the limits of steganography.- Trials of traced traitors.- Establishing big brother using covert channels and other covert techniques.- Covert channels-A context-based view.- Covert channel analysis for Stubs.- Anonymous addresses and confidentiality of location.- MIXes in mobile communication systems: Location management with privacy.- Hiding Routing information.- The Newton channel.- A progress report on subliminal-free channels.- Modeling cryptographic protocols and their collusion analysis.- A secure, robust watermark for multimedia.- Modulation and information hiding in images.- Watermarking document images with bounding box expansion.- The history of subliminal channels.- Blind decoding, blind undeniable signatures, and their applications to privacy protection.- Practical invisibility in digital communication.- Fractal based image steganography.- Echo hiding.- Tamper resistant software: an implementation.- Oblivious key escrow.- HMOS: Her Majesty's Orthography Service.- Information hiding terminology.