Showing papers on "Watermark published in 1997"

Secure spread spectrum watermarking for multimedia

Abstract: This paper presents a secure (tamper-resistant) algorithm for watermarking images, and a methodology for digital watermarking that may be generalized to audio, video, and multimedia data. We advocate that a watermark should be constructed as an independent and identically distributed (i.i.d.) Gaussian random vector that is imperceptibly inserted in a spread-spectrum-like fashion into the perceptually most significant spectral components of the data. We argue that insertion of a watermark under this regime makes the watermark robust to signal processing operations (such as lossy compression, filtering, digital-analog and analog-digital conversion, requantization, etc.), and common geometric transformations (such as cropping, scaling, translation, and rotation) provided that the original image is available and that it can be successfully registered against the transformed watermarked image. In these cases, the watermark detector unambiguously identifies the owner. Further, the use of Gaussian noise, ensures strong resilience to multiple-document, or collusional, attacks. Experimental results are provided to support these claims, along with an exposition of pending open problems.

An invisible watermarking technique for image verification

Abstract: We propose a new method for invisibly watermarking high-quality color and gray-scale images. This method is intended for use in image verification applications, where one is interested in knowing whether the content of an image has been altered since some earlier time, perhaps because of the act of a malicious party. It consists of both a watermark stamping process which embeds a watermark in a source image, and a watermark extraction process which extracts a watermark from a stamped image. The extracted watermark can be used to determine whether the image has been altered. The processing used in the stamping and extraction processes is presented. We also discuss some advantages of this technique over other invisible watermarking techniques for the verification application; these include a high degree of invisibility, color preservation, ease of decoding, and a high degree of protection against retention of the watermark after unauthorized alterations.

Protecting images with an image watermark

Abstract: A robust means of watermarking a digitized image with a highly random sequence of pixel brightness multipliers is presented. The random sequence is formed from ‘robust-watermarking-parameters’ selected and known only by the marker and/or the marking entity. A watermarking plane is generated having an element array with one-to-one element positional correspondence with the pixels of the digitized image being marked. Each element of the watermarking plane is assigned a random value dependent upon a robust random sequence and a specified brightness modulation strength. The so generated watermarking plane is imparted onto the digitized image by multiplying the brightness value or values of each pixel by its corresponding element value in the watermarking plane. The resulting modified brightness values impart the random and relatively invisible watermark onto the digitized image. Brightness modulation is the essence of watermark imparting. Detection of an imparted watermark requires knowing the watermarking plane with which the watermark was imparted. Regeneration of the watermarking plane requires knowledge of the robust-marking-parameters used in its formulation. This is generally only known to the marker and/or marking entity. Once regenerated, the watermarking plane is used together with a verifying image located in a ‘visualizer’ to demonstrate the existence of the watermark. The process of watermark detection is enhanced by application of a blurring filter to the marked image before detection is attempted.

A multiresolution watermark for digital images

Abstract: We introduce a new multiresolution watermarking method for digital images. The method is based on the discrete wavelet transform (DWT). Pseudo-random codes are added to the large coefficients at the high and middle frequency bands of the DWT of an image. It is shown that this method is more robust to often proposed methods to some common image distortions, such as the wavelet transform based image compression, and image halftoning. Moreover, the method is hierarchical. The computation load needed to detect the watermark depends on the noise level in an image.

DCT-based watermark recovering without resorting to the uncorrupted original image

Abstract: Digital watermarking has been proposed as a viable solution to the need of copyright protection and authentication of multimedia data in a networked environment, since it makes it possible to identify the author, owner, distributor or authorized consumer of a document In this paper a new watermarking technique to add a code to digital images is presented; the method operates in the frequency domain embedding a pseudo-random sequence of real numbers in a selected set of DCT coefficients Watermark casting is performed by exploiting the masking characteristics of the human visual system, to ensure watermark invisibility The embedded sequence is extracted without resorting to the original image, so that the proposed technique represents a major improvement to methods relying on the comparison between the watermarked and original images Experimental results demonstrate that the watermark is robust to most of the signal processing techniques and geometric distortions

Method and apparatus for embedding data, including watermarks, in human perceptible sounds

Abstract: A technique for hiding of data, including watermarks, in human-perceptible sounds, that is, audio host data, is disclosed. In one embodiment a method comprises three steps. In the first step, data to be embedded is inputted. In the case of a watermark, this data is a unique signature, and may be a pseudo-noise (PN) code. In the case of hidden data to be embedded in the host data, this data is the hidden data itself, or the hidden data as spread against the frequency spectrum by a pseudo-noise (PN) code. In the second step, the inputted data is embedded within the host data, in accordance with a perceptual mask of the host data. The perceptual mask determines the optimal locations within the host data to insert the inputted data. In the case of sounds, these optimal locations are determined by reference to the human auditory system. In the third step, the host data, with the embedded data, is further masked by a non-frequency mask. In the case of audio data, the non-frequency mask is a temporal mask.

Review of watermarking and the importance of perceptual modeling

Abstract: A watermark embeds an imperceptible signal into data such as audio, video and images, for a variety of purposes, including captioning and copyright control. In this paper, we first outline the desirable characteristics of digital watermarks. Previous work in digital watermarking is then reviewed. Early work identified redundant properties of an image (or its encoding) that can be modified to encode watermarking information. The early emphasis was on hiding data, since the envisioned applications were not concerned with signal distortions or intentional tampering that might remove a watermark. However, as watermarks are increasingly used for purposes of copyright control, robustness to common signal transformations and resistance to tampering have become important considerations. Researchers have recently recognized the importance of perceptual modeling and the need to embed a signal in perceptually significant regions of an image, especially if the watermark is to survive lossy compression. However, this requirement conflicts with the need for the watermark to be imperceptible. Several recent approaches that address these issues are discussed.

A robust digital image watermarking method using wavelet-based fusion

Abstract: We present an approach for still image watermarking in which the watermark embedding process employs multiresolution fusion techniques and incorporates a model of the human visual system (HVS). The original unmarked image is required to extract the watermark. Simulation results demonstrate the high robustness of the algorithm to such image degradations as JPEG compression, additive noise and linear filtering.

A spread spectrum watermark for embedded signalling

Abstract: A watermark is embedded into audio/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 spatial or temporal local averaging of the frequency coefficients of the watermarked data.

Invisible image watermark for image verification

Abstract: A system quickly verifies that the content of an image has not been changed since an earlier time when the content of that image was stamped. The system consists of a stamping process that embeds stamping information into a source image and produces a verification key, and a verification process that extracts stamping information from a stamped source image based on the verification key. Furthermore, the verification process produces an image itself, from which the verification can be readily judged visually or by use of a computer or other display device. In the verification process, the changes in an image can be detected and localized. The image stamping process further includes an error diffussion process so that the effects of combining the stamping information with the original image are not readily perceptable. An image is safeguarded against malicious manipulations and the proprietary rights are protected by maintaining the integrity of the image content.

Detecting a watermark embedded in an information signal

Abstract: A watermark embedded in an information signal is detected by correlating said information signal with a plurality of watermarks Wj(n) The respective amounts of correlation C(i,j) are then evaluated to determine the watermark embedded in the signal xi(n) The invention provides a significant improvement of the detection by predictive filtering (25) the information signal and/or predictive filtering (26) the applied watermark prior to the process of correlating the signals

Digital watermarking of MPEG-2 coded video in the bitstream domain

Abstract: Embedding information into multimedia data, also called watermarking, is a topic that has gained increased attention. For video broadcast applications, watermarking schemes operating on compressed video are desirable. We present a scheme for robust watermarking of MPEG-2 encoded video. The watermark is embedded into the MPEG-2 bitstream without increasing the bit-rate, and can be retrieved even from the decoded video and without knowledge of the original, unwatermarked video. The scheme is robust and of much lower complexity than a complete decoding process followed by watermarking in the pixel domain and re-encoding. Although an existing MPEG-2 bitstream is partly altered, the scheme avoids visible artifacts by adding a drift compensation signal. The scheme has been implemented and the results confirm that a robust watermark can be embedded into MPEG encoded video which can be used to securely transmit arbitrary binary information at a data rate of several bytes/second. The scheme is also applicable to other hybrid coding schemes like MPEG-1, H.261, and H.263.

Adaptive watermarking in the DCT domain

Abstract: An adaptive watermarking technique is introduced in this work. A regional perceptual classifier is employed to assign a noise sensitivity index to each region. The watermark is inserted in the original image according to this index by using block DCT. The detection of the watermark is designed to achieve a desired false alarm probability.

Watermarking of digital object

Abstract: A technique for identifying digital object using a digital watermark. The technique includes the steps of encrypting a message derived from source data on the digital object, to obtain an encrypted message digest (S); deriving a watermark from the encrypted message digest (S); and incorporating the watermark into the source data. The encryption is preferably done with a public key encryption system. The message to be encrypted can be obtained via performing a hash function on the source data on the digital object to obtain a message digest (M). The message digest (M) is the message encrypted with the signature encryption key to obtain the encrypted message digest (S). The watermark is resistant to cropping, scaling, and truncation.

Method and apparatus for scene-based video watermarking

Abstract: A method and apparatus for the scene-based watermarking of video data is disclosed. In one embodiment, each of a number of frames of a scene of video host data undergoes a temporal wavelet transform, from which blocks are extracted. The blocks undergo perceptual masking in the frequency domain, such that a watermark is embedded therein. Once the watermark block is taken out of the frequency domain, a spatial mask of the original block is weighted to the watermark block, and added to the original block to obtain the watermarked block.

Fast public-key watermarking of compressed video

Abstract: Most watermarking techniques for images and video techniques involve a private key, for example a pseudo-noise signal, which is required for retrieval of the watermark information. This key is typically not public, because publication of the key would give rise to attacks on the watermark. In practical systems, however, watermarking techniques are required that enable public decoding of the watermark. In this paper, an extension of spread-spectrum watermarking is presented which enables public decoding and verification of the watermark, without at the same time giving the possibility of removing the watermark. The underlying idea, is to make only parts of the pseudo-noise key public. The scheme can be combined with a fast compressed-domain embedding technique to facilitate on-the-fly compressed-domain public-key watermarking.

Digital watermarking to resolve multiple claims of ownership

Abstract: A method and apparatus for digital watermarking to resolve multiple claims of ownership is disclosed. According to one embodiment of the invention, a first watermark requiring the host data for detection is embedded into the host data. A second watermark is also embedded into the host data. According to another embodiment of the invention, a pseudo-random sequence acting as a watermark is generated based on two random keys. One of the two random keys is related to the author of the host data into which the watermark is to be embedded, whereas the other of the two random keys is dependent on the host data itself.

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

Method and apparatus for embedding a watermark into a digital image or image sequence

Abstract: A method and apparatus for watermarking an image or sequence of images without limiting the watermark signal. The watermarking apparatus includes a conventional DCT unit and quantizer for generating an array of quantized DCT coefficients. The array is watermarked by masking the array to select certain ones of the DCT coefficients that are then replaced by zero values to form a masked array. The masked array is further processed by a watermark inserter that replaces the zero valued coefficients with predefined watermark coefficients to form a watermarked array of DCT coefficients, e.g., a watermarked image. A decoder for decoding the bitstream thusly generated and for removing the embedded watermark is also taught.

Public watermarks and resistance to tampering

Abstract: Public watermarks allow embedded signals to be extracted from audio and video content for a variety of purposes. One application is for copyright control, where it is envisaged that digital video recorders will not permit the recording of content that is watermarked as "never copy". In such a scenario, it is important that the watermark survive both normal signal transformations and attempts to remove the watermark so that an illegal copy can be made. In this paper, we discuss to what extent a public watermark can be resistant to tampering and describe a variety of possible

Automatic adjustment of image watermark strength based on computed image texture

Abstract: A system and method of automatically adjusts watermark strength of a watermarked image based on the content of the image. The described system includes a process by which the correct watermark strength is estimated with a model of preferred watermark strength based upon human perception as measured with a test group. Preferred watermark strength of a watermark within a watermarked reference image is determined and parameter constants associated with measured image texture values for the reference image are then determined. Image texture values are measured for a particular image to be watermarked, and these determined parameter constants are used to predict the strength of the watermark for the particular image. Images are watermarked by modifying the luminance of those pixels that fall within a mask specifying the watermark design. In this way, the chromaticity of the pixel remains constant but the luminance changes. The amount by which the luminance is changed is dependent on the desired strength of the watermark: a stronger watermark demands a larger change in the luminance.

Method and apparatus for imbedding a watermark into a bitstream representation of a digital image sequence

Abstract: A method and apparatus that inserts watermark information directly into an encoded video bitstream. The method identifies specific blocks or macroblocks in an encoded video bitstieam and inserts the watermark information directly into the bitstream such that these selected blocks are replaced with a block containing watermark information or augmented with watermark information.

Object-based transparent video watermarking

Abstract: We present a watermarking procedure to embed copyright protection into video sequences. To address issues associated with video motion and redundancy, individual watermarks are created for objects within the video. Each watermark is created by shaping an author and video dependent pseudo-random sequence according to the perceptual masking characteristics of the video. As a result, the watermark adapts to each video to ensure invisibility and robustness. Furthermore, the noise-like watermark is statistically undetectable. The watermark also resolves multiple ownership claims. We demonstrate the robustness of the watermarking procedure to video degradations, e.g., those that result from noise, MPEG compression, cropping, and printing and scanning.

Digital watermarking by adding random, smooth patterns

Abstract: A digital image is "watermarked", that is, authenticated by an embedded pattern. The pattern is created by hashing the image and adding a signature element. Manipulating this result by the seed for a random number generator leads to an initial two dimensional random black-and-white pattern. This pattern is manipulated by a cellular automaton and smoothed before being added to the original image. To determine whether the image is authentic, one retrieves the watermark by subtracting the watermarked image from the original to obtain the difference. The value of the correlation between the difference thus obtained and the smoothed pattern determines the presence or absence of the watermark.

Protecting publicly-available images with an invisible image watermark

Abstract: A method is presented for marking high-quality digital images with a robust and invisible watermark. A broad definition of robustness, stated as fundamental, is used. It requires the invisible mark to survive and remain detectable through all image manipulations that in themselves does not damage the image beyond useability. These manipulations include JPEG "lossy" compression and, in the extreme, the printing and rescanning of the image. The watermark is imparted onto an image as a random, bur reproducible, small modulation of its pixel brightnesses, and becomes a permanent part of the marked image. Detecting the imparted watermark, especially after image manipulation, is a daunting task. It is one of detecting the presence of a known small modulation of a random carrier where the carrier is composed of the pixel brightness values of the unmarked image. The method presented exploits the not well understood but superb ability of the human visual system to recognize a correlated pattern in a scatter diagram called a "visualizer-coincidence image." Results of application of the method are presented.

Method and apparatus for video watermarking using perceptual masks

Abstract: A method and apparatus for the watermarking of video data is disclosed. In one embodiment, discrete objects are extracted from the video host data. Each is assigned and embedded with a watermark. The watermark is embedded by generating the watermark, applying it to a perceptual mask of the block, spatially masking the resulting block, and re-adding the block to the result. The objects are collected into a database so that an object may be tracked as it is transformed from frame to frame of the video host data.

Perceptual watermarking of still images

Abstract: Content providers on the Internet are faced with the problem of how to secure electronic data. This problem has generated research activity in the area of digital watermarking of electronic content. The challenge is to introduce a digital watermark that is both transparent and highly robust to common signal processing and possible attacks. The two basic requirements for an effective watermarking scheme, robustness and transparency, conflict with each other. We propose a watermarking technique for digital images that is based on utilizing visual models which have been developed in the context of image compression. The visual models give us a direct way to determine the maximum amount of watermark signal that each portion of an image can tolerate without affecting the visual quality of the image. This allows us to provide the maximum strength watermark which in turn, is extremely robust to common image processing and editing such as JPEG compression, rescaling, and cropping. Our watermarking scheme is based on a DCT framework which allows for the possibility of directly watermarking the JPEG bitstream. Our scheme is shown to provide very good results both in terms of image transparency and robustness.

Controlling video or image presentation according to encoded content classification information within the video or image data

Abstract: Provided is a method and a system for automatically controlling display of video or image data in dependence on content classification information which is integrated within the data by means of invisible digital watermarking techniques. A controller decodes the watermarked content codes and then prevents displaying of certain material, by overlaying the display with blanking data, if the codes match certain stored codes which the controller has been set to respond to. The use of invisible digital watermark codes by a controller which operates in response to the watermark codes provides reliable control since the codes are more difficult for unauthorized persons to detect and remove than other embedded codes would be.

On resolving rightful ownerships of digital images by invisible watermarks

Abstract: Digital watermarking has been proposed as a means for copyright protection of multimedia data. This paper first discusses some scenarios in which many current watermarking schemes fail to resolve the rightful ownership of an image. We then identify the key problems and discuss some crucial requirements for a valid invisible watermark detection. In particular, we argue that, for the particular application of resolving rightful ownership using invisible watermarks, it might be crucial to require that the original image not be directly involved in the watermark detection process. A general framework for validly detecting the invisible watermarks is then proposed. We show the effectiveness of this technique based on some visual-model-based watermarking schemes.