462 results about "Watermark method" patented technology

A digital watermarking process whereby an invisible watermark inserted into a host image is utilized to determine whether or not the image has been altered and, if so, where in the image such alteration occurred. The watermarking method includes the steps of providing a look-up table containing a plurality of coefficients and corresponding values; transforming the image into a plurality of blocks, wherein each block contains coefficients matching coefficients in the look-up table; and embedding the watermark in the image by performing the following substeps for at least some of the blocks: First, a coefficient is selected for insertion of a marking value representative of a corresponding portion of the watermark. Next, the value of the selected coefficient to used to identify a corresponding value in the look-up table. Finally, the identified coefficient is left unchanged if the corresponding value is the same as the marking value, and is changed if the corresponding value is different from the marking value. After the insertion of the watermark, the image may be stored in a lossy-compression form, thus permitting efficient storage and distribution. Moreover, the method may be used to produce two output signals for authentication: (1) a meaningful pattern to facilitate a quick visual check, and (2) an additional signal to detect unauthorized alteration. The method can be applied to an image compressed using JPEG or other techniques, such as Wavelet compression, and the marked image can be kept in the compressed format. Any alteration made on the marked image can be localized, making the method suitable for use in a "trustworthy" digital camera or camcorder.

One inventive aspect pertains to a watermarking mechanism that allows a watermark to be determined from only a part of the video sequence without human intervention and without reference to the original watermarked frames. This watermark has improved invisibility, detection reliability and robustness. Invisibility is improved through the inclusion of frame difference parameters to calculate the amplitude of the watermark. Detection reliability and robustness can be improved by assuring that opposite signed values for the pseudo-random number sequence are spatially near each other and using data blocks forming the data sets, respectively. Another inventive aspect pertains to a watermarking mechanism that is exclusively dependent on the data contained in the data sets and is completely interoperable between spatial and compressed domains.

Method of embedding watermarks in a signal encoded by an encoder having a feedback loop, for example, a sigma-delta modulator (21,22,23). A digital watermark pattern (w) is embedded in the signal (z) by modifying selected samples (for example, replacing every 100th bit) of the encoded signal (y) by samples of the watermark pattern. The circuit (24) for modifying the samples is located inside the loop of the encoder. The effect of watermarking is thus compensated in subsequent encoding steps and the signal-to-noise ratio is only slightly affected.

Digital watermark methods for encoding auxiliary data into a host signal are used to authenticate physical and electronic objects. In one implementation, an identification document includes electronic circuitry. The electronic circuitry includes an image of an authorized bearer of the identification document. The image includes first digital watermarking having a plural-bit identifier. In some cases, the identification document includes a printed image of the authorized bearer of the identification document. The printed image includes second digital watermarking therein. The first digital watermarking and the second digital watermarking can be cross-correlated for authentication of the identification document.

The present invention discloses an image watermark way applied to protecting copyright. It converts two-dimensional pels matrix to a two-value sequence group, splits the original image into 8*8 pels in the pels area, and processes discrete cosine conversion to (DCT) convert every pels area to frequency area. By fake radnom selecting block texture selecting block and illumination selecting block, it can conform which area block need to embed the watermark, and can sort them Zigzag. It embeds the encryption part of the watermark sequence group into the direct-current factor position of the random selecting block, also embeds the texture part and illumination part into respective low frequency factor position.

The invention discloses a multi-bit digital watermark method against the print scanning and the geometric transformation, which comprises the following steps: embedding the watermark in dispersion Fourier amplitude coefficient of the image; determining which Fourier amplitude coefficient every watermark bit embeds in according to the dispersion logarithmic polar coordinate of the Fourier amplitude coefficient; making the watermark detecting and extracting out-of-step when the image is carried out the geometric transformation of the pantographic rotating or the print scanning; synchronizing the information watermark according to the relation of the original mode and embedded mold when the watermark is detected and extracted because the pantograph and the rotating of the image corresponds with the translation of the Fourier logarithmic polar coordinate field at the radial and angel direction; extracting the meaning watermark information bit string; introducing the real interpolation and saving the time because the watermark embedding and detecting process doesn' t need the image interpolation arithmetic for the image and the Fourier amplitude coefficient; protecting the embedded mode. The invention can apply to the copyright protection of the digital image and video, false proof of the file and evidence, the monitoring of video broadcast.

A vector geographic space data watermarking-method based on integer wavelet transform includes fetching original vector geographic space data from mapping databank, enciphering watermark information with chaos sequence, carrying out integer wavelet transform on coordinate string of said geographic space data and embedding watermark information into low frequency coefficient of wavelet transform; picking up watermark information by comparing wavelet coefficient mutual relation of data string to be tested to original reference data string when watermark is required to be picked up.

According to an inventive scheme for introducing a watermark into an information signal, the information signal is at first transferred from a time representation to a spectral/modulation spectral representation). The information signal is then manipulated in the spectral/modulation spectral representation in dependence on the watermark to be introduced to obtain a modified spectral/modulation spectral representation, and subsequently an information signal provided with a watermark is formed based on the modified spectral/modulation spectral representation. An advantage is that, due to the fact that the watermark is embedded and/or derived in the spectral/modulation spectral representation or range, traditional correlation attacks as are used in watermark methods based on a spread-band modulation cannot succeed easily.

The invention provides a reversible watermark method based on histogram shifting and has significant practical values for protecting multimedia copyrights. By means of the reversible watermark method, traditional histogram shifting algorithms are improved in two aspects, firstly, 1 and 0 in a bite map are more imbalanced by arranging a generation process of the bit map on watermark embedding rather than in a non-pretreatment stage, so that compression is easier, and embedding capacity is improved; and secondly, the reversible watermark method is a two-step embedding method. The watermark blind extraction is achieved and troubles that the histogram shifting method needs extra side information transmitting are solved by dividing an image into an upper large area and a lower large area, subjecting the upper area to the watermark embedding, embedding the generated side information into the lowest significant bit containing watermark pixels in the area, and embedding the left watermark information and the replaced lowest significant information into the lower area.

The invention provides a vector map watermark method based on object property characteristics, comprising: using user input to generate watermark codes needed to be embedded; according to watermark capacity, defining the scale of the watermark formed by watermark objects that embedded into object set; for the vector map of the object watermark, using a modified grid density spatial cluster analysis method to generate a watermark embedded target set; in the property document of the vector map, searching the property characteristic information corresponding to the vector object in the embedded target set; according to the watermark information generated in the step (1), randomly selecting the vector element in the generated watermark embedded target set, embedding watermark code into the property coordinate information of the element; disordering the vector formed by all vector object sequences embedded by watermark marks, storing iteration number as a key; reading vector map property document, using a watermark detection program to extract watermark information, and judging the watermark existence state of map carrier according to watermark similarity.

A digital watermark method for image includes such steps as inputting product data, converting it to frequency domain data, inputting private information of user, generating watermark information by RS unit, embedding the watermark into the frequency domain of product, converting it to airspace time domain to become product data, outputting the product with watermark. The watermark check includes converting the product data to frequency domain data, generating check information from private information, correlation analyzing between said frequency domain data and check information, and explaining.

A watermarking method and system are provided. The watermarking system includes a server and a client in communication with each other. At first, the client sends a login request to the server. The server authenticates an access right of the client to access specific multimedia data and generates an identification code uniquely associated with the client according to the login request if the client is authenticated to have the access right to access the multimedia data. An on-screen watermark is generated according to the identification code and added onto the multimedia data to be played. The watermark-generating and adding step may be performed by either the server or the client. The on-screen watermark can be detected by a watermark-detecting method and system to trace privacy source.

The invention discloses a high-capacity reversible watermark method based on predication and companding technique. Through the introduction of the companding technique, the invention includes two processes: watermark embedding and watermark extracting. The invention effectively solves the problem of capacity consumption of position drawing in reversible watermark algorithm, and achieves high embedding capacity even in the situation of low threshold value. Meanwhile, due to the operation of data re-embedding after the compression of high predication errors, the invention still can maintain high peak signal to noise ratio (PSNR value).

The invention provides a method and apparatus for watermarking a document, the method comprising: associating the document with an identification number; generating (70) a first set of numbers using a seed for the number generation comprising or derived from the identification number; applying a transform (62) to at least a portion of an image of the document to form a transform of the image; defining a second set of numbers comprising transform coefficients from the transform of the image; forming a modified second set of numbers based on the first set and the second set; substituting the modified second set for the second set in the transform of the image to form a modified transform (72); and applying an inverse (74) of the transform to the modified transform to thereby produce a modified image of the document; whereby the modified image of the document or an output of the modified image constitutes the watermarked document.

Method and apparatus for controlling copying (recording) of an audio or video signal transmitted over a cable television or direct satellite broadcast system or the internet. Copyrighted (or other) audio or video material is protected from unwanted copying (recording) by the combination of a watermark embedded in the audio or video signal at the cable television head end together with additional copy protection data inserted in the audio or video signal, the data being a second watermark. The watermarks are audio or video watermarks embedded in active portions of the audio or video signal. The watermarks are, e.g., predetermined function s of the active video or audio. Only if the consumer is willing to pay a fee is the video or audio signal with both the watermarks transmitted to his recording device which then compares the watermarks, and only if they match is the recording permitted.

The invention provides a real-time video watermark method resisting geometric attacks mainly suitable for a video file based on coding. The method directly transforms a partitioning DCT coefficient to an integral DCT coefficient through a quick speed change method, then self-adaptingly modifies a low frequency coefficient value in the integral DCT domain to embedding a watermark signal, transforms a difference value between the watermark embedded integral DCT coefficient and an original coefficient to a difference value of the partitioning DCT coefficient, then rewriting the different value to the partitioning DCT coefficient. The watermark detection is performed in an air space, because a detection process is performed with a video play back, at the same time the video is fully decoded, and is directly performed the integral DCT transformation from the air space, then in order to resist rotary attacks, the detection video is performed a rotary compensation, and is performed a watermark pick-up according to a rule at the embedding time. The results show that the method has very good robustness to a common signal treatment and the conventional geometric attacks (row-column removal, rotation, equal proportion scaling, aspect ratio attack, linear transform, random distortion, cutting and several coalition attacks or the like).

The invention discloses an H.264 compression bit stream oriented video watermark method. The method comprises the following steps of: generating an authentication code according to a predictive mode of a 4*4 brightness block in an I film; and embedding the authentication code in the film-grade bit stream by modulating variable-length code words of some motion sub-blocks of a B film and a P film, wherein the modulation is performed based on a mapping rule between the variable-length code words and the bits to be embedded, and the mapped variable-length code words is extremely similar to the original variable-length code words. Because in the method, the video bit stream is unnecessarily pre-processed, and comparison and replacement operations are performed by selecting the proper variable-length code words only from the H.264/AVC compression bit stream in the watermark embedding process without a huge number of operations, so that the method has the advantages of low computing complexity, high safety and high practicability, and can better meet the requirements of the real-time video processing.

A digital watermark method resisting against geometric attack includes relating watermark information to image character region, generating local character region with invariance on geometric attack by utilizing most stable Harris character point in image, making said region to be round character region by image normalization, carrying out two-stages of wavelet transforms on these round character regions, selecting revision coefficient regions to embed watermark at the second stage wavelet transform and realizing watermark-embedding. The method for picking up watermark is also disclosed.

The invention discloses a method for inlaying a digital watermark, comprising step A1 of transforming a watermark image to generate a phase holographic image; step B1 of transforming a digital carrier image by means of wavelet; step C1 of synthesizing the phase holographic image after being weighted with a wavelet low-frequency coefficient obtained by transforming a digital carrier image by means of wavelet; step D1 of inversely transforming the synthesized wavelet low-frequency coefficient to generate an image having a watermark. The invention also discloses a corresponding digital watermark detecting method and a digital watermark inlaying and detecting device used to implement the inlaying and detecting method. Compared with the prior digital watermark method, concealment and robustness of the invention are obviously improved. Furthermore, the invention has the shear resistance of the holographic watermark scheme and avoids problem of interference between conjugate images.

The invention discloses a robust image watermark new method based on a local Tchebichef moment, mainly solving the problem that a watermark arithmetic based on image characteristic at present can not effectively resist general image processing and geometry attack simultaneously. The method comprises the steps as follows: firstly, extracting characteristic points of an original image by utilizing a Harris-Laplace detection operator, and obtaining a group of stable and mutually independent round characteristic areas through characteristic selection; then obtaining a geometrically unchanged round characteristic area through principle direction alignment; and finally, calculating the Tchebichef moment in an inscribed square image block of the round characteristic area, and embedding a watermark through dithering quantized modulation to modify an amplitude value with low-level Tchebichef moment. In detection, the modified low-level Tchebichef moment is obtained through the dithering quantized modulation, and a minimum distance is utilized to realize the blind extraction of the watermark. The invention has favorable nonvisibility, excellent robust performance for general image processing, geometry attach and combined attach and superior performance to similar methods and can be used for copyright protection for different images.

A robustness watermarking method plays a significant role in the field of copyright certification. A main problem to be considered in the design of the robustness watermarking method is how to improve the robustness as high as possible on the basis of ensuring excellent invisibility of a watermark. The invention designs a high-robustness dual transform domain image zero watermarking method by using an energy concentration effect of low-frequency sub-bands of a wavelet transformed image and the singular value stability of singular value decomposition. The method comprises the following steps: firstly, subjecting an original image to discrete wavelet transform; secondly, selecting a low-frequency subband for block singular value decomposition; and finally, generating a robustness watermark by judging the parity of a number in the top digit of a maximum singular value of each subblock. The method avoids any change in the original image, thereby having excellent invisibility. Compared with other overwhelming majority of robustness watermarking methods, the method has stronger anti-attack robustness. The method can realize blind copyright certification.

The invention relates to a DWT-SVD robust blind watermark method based on multilevel DCT. The method comprises a watermark embedding method and a watermark extraction method. The watermark embedding method includes the steps that discrete waterlet transformation is conducted on an original image, a low-frequency sub-band of the original image is divided into small blocks, multilevel DCT is conducted on each small block, chaotic encryption is conducted on watermarks to be embedded, multilevel DCT coefficients of each small block form a new matrix, and the encrypted watermarks are embedded into a singular value matrix of each new matrix. The watermark extraction method is the inverse process of the watermark embedding method and includes the steps of extraction of the encrypted watermarks and decryption and restoration of the watermarks through secret keys. According to the method, by the combination of the advantages of DWT and SVD on the digital watermark respect and the utilization of the energy concentration characteristic of multilevel DCT, data of which values are large are acquired, the embedded capacity of the watermarks is increased, the characteristic of being good in robustness is still maintained, and the problem of conflicts between the capacity of the watermarks and robustness is well solved.