Abstract: In a method and arrangement for embedding and detecting a watermark in an information signal, the embedded watermark (Wi) is selected (13) from a plurality of watermarks (W1 . . . WN) in dependence upon a property P of the signal. An example of such a property is the distribution of luminance values of the current video image as calculated by an analysis circuit (12). The corresponding watermark detector performs the same operation: the watermark being looked for depends on the same signal property. It is achieved with the invention that the embedded watermark changes from time to time as a function of the information signal content, so that it cannot easily be hacked.

Abstract: Disclosed is a method for the detection of pseudo-symmetric watermarks in an information signal. The method includes receiving the information signal, wherein the watermark is embedded in respective sections of the information signal by tiling a finite number of a plurality of watermark patterns, accumulating the sections, and correlating the accumulated sections with a sum of the plurality of watermark patterns. In particular, the information signal is folded as if there was only a single basic pattern. The presence of the watermark is then detected by a cyclic sliding correlating.

Abstract: The invention discloses a method of embedding information for high quality restoration of a media signal (typically an audio-visual signal) in a lower quality version of the signal. To this end, the signal x is encoded using a high quality encoder (Q2). The code sequences z produced by the high quality encoder are mapped into code sequences y that are associated with a hypothetical lower quality encoder (Q1). The latter code sequences y are transmitted. A simple decoder will decode the received sequences y, and thus reproduce a low quality version of the signal. A more sophisticated decoder is arranged to inversely map the received code sequences y into the code sequences z, that were actually produced by the high quality encoder (Q2). The sophisticated decoder will thus reproduce a higher quality version of the same signal.

Abstract: The invention relates to a method of checking the correct operation of a signal transformation wherein a input signal is transformed into an output signal. The method comprises: deriving a first robust feature from the input signal; deriving a second robust feature from the output signal; comparing said first and second robust features; in case of sufficient sumilarity, concluding a correct operation of said signal transformation, and in case of insufficient sumilarity, concluding a false operation of said signal transformation. In a special embodiment, the method is applied wherein the first robust feature is embedded in the input signal through watermark technology, the thus obtained signal being transmitted to a receiver so as to retrieve an output signal corresponding to said input signal.

Abstract: A method of maintaining a database comprising a fingerprint of and an associated set of metadata for each of a number of multimedia objects. Respective portions (201, 202, 203, 204, 205) of the database are distributed over respective file sharing clients (101-105) connected to a file sharing network (100) arranged for sharing said number of multimedia objects. File sharing clients (101-105) can maintain their own respective portions (201-205) of the database, or transmit fingerprints and metadata to another file sharing client. In the latter case, the other file sharing client is preferably a supermode in the file sharing network (100).

Abstract: The invention addresses the problem of scale degradations that may occur in watermarking schemes based on quantization index modulation (QIM). In accordance with the invention, the quantization step size (D) being employed by the embedder (11) and detector (21) is derived (12, 22) from a measurable characteristic parameter which has the property that, when the applied signal is scaled by a factor (a), it is scaled by substantially the same factor. In a preferred embodiment, said parameter is the square root of the energy of the signal (), and the quantization step is a predetermined fraction (a) thereof.

Abstract: A video watermarking scheme is disclosed, which is designed for the digital cinema format, as it will be used on large projector screens in theaters. The watermark is designed in such a way that it has minimal impact on the video quality, but is still detectable after capture with a handheld camera and conversion to, for instance, VHS, CD-Video or DVD format. The proposed watermarking system only exploits the temporal axis. This makes it invulnerable to geometrical distortions generally caused by such a way of capturing. The watermark is embedded by modulating a global property of the frames (e.g. the mean luminance) in accordance with the samples of the watermark. The embedding depth is preferably locally adapted within each frame to local statistics of the respective image. Watermark detection is performed by correlating the watermark sequence with extracted mean luminance values of a sequence of frames.

Abstract: For some video processing applications, most notably watermark detection (40), it is necessary to add or average (parts of) the two interlaced fields which make up a frame. This operation is not trivial in the MPEG domain due to the existence of frame-encoded DCT blocks. The invention provides a method and arrangement for adding the fields without requiring a frame memory or an on-the-fly inverse DCT. To this end, the mathematically required operations of inverse vertical DCT (321) and addition (322) are combined with a basis transform (323). The basis transform is chosen to be such that the combined operation is physically replaced by multiplication with a sparse matrix (32). Said sparse matrix multiplication can easily be executed on-the-fly. The inverse basis transform (35) is postponed until after the desired addition (33, 34) has been completed.

Abstract: The invention relates to a method for encoding a stream of bits of a signal relating to a binary source into a stream of bits of a signal relating to a binary channel, the binary source comprising a main source and a secondary source, the main source being encoded in a main channel and the secondary source being encoded in a secondary channel, the secondary channel being embedded in the main channel in order to form the binary channel, wherein the binary channel is divided in blocks, each block comprising a number of user bits and that in at least one of the blocks the secondary channel also is used for encoding non-user bits.

Abstract: The invention relates to a method of storing data on a rewritable data storage medium, to a corresponding storage medium, to a corresponding recording apparatus and to a corresponding playback apparatus. Copy-protective measures require that on rewritable storage media some data must be stored which shall not be modifiable or erasable by consumer end products. A practical problem is the storage of large quantities of such data in a fixed data area. Typically the capacity is limited to a few bits. Meanwhile the amount of copy protection data that needs to be stored may well exceed the storage capacity available in the read-only fixed data area. The invention therefore proposes to write the copy protection data as system data in the recordable data area (4), e.g. as part of the formatting of the medium (1).

Abstract: An arrangement for embedding a watermark in an information signal is disclosed. In order to make the embedded watermark more robust against hacking, a property of the watermark is randomized (11) which is irrelevant for the watermark detection. One example is randomizing (111) the magnitudes (abs) of the Fourier transformed watermark. Another example is randomly shifting the spatial or temporal position of the watermark with respect to the signal at a relatively low temporal frequency. The invention allows embedding (13) of spatially different watermarks without affecting the performance of a detector.

Abstract: The invention relates to a method of storing data on a rewritable data storage medium, to a corresponding storage medium, to a corresponding recording apparatus and to a corresponding playback apparatus. Copy-protective measures require that on rewritable storage media some data must be stored which shall not be modifiable or erasable by consumer end products. A practical problem is the storage of large quantities of such data in a fixed data area. Typically the capacity is limited to a few bits. Meanwhile the amount of copy protection data that needs to be stored may well exceed the storage capacity available in the read-only fixed data area. The invention therefore proposes to write the copy protection data as system data in the recordable data area (4), e.g. as part of the formatting of the medium (1).

Abstract: A method and arrangement for detecting a watermark in a suspect signal, in which the watermark is embedded by adding a watermark pattern w to a signal p with a given embedding strength s (“additive embedding”: q=p+sw), includes correlating (2,3) it with the suspect signal. Recently, “multiplicative embedding” has been proposed (q=p(1+sw)). In this case, multiplicatively embedded watermarks are detected by raising (1) the signal to a power &bgr; prior to correlating it with the watermark. The power &bgr; may be fixed (e.g., &bgr;=2) or derived from a statistical analysis (5) of the signal.

Abstract: Data is hidden in an information signal by encoding payload in to relative positions and/or polarities of multiple (possibly equal) embedded watermarks. The payload is retrieved by computing the correlation between the watermark(s) and the signal as a function of the position. The distance between peaks of the correlation function represents the payload. In order to precisely detect said distance, even if the peaks are smeared, the correlation function in a window (w1) around one peak (p1) is compared with the correlation function in a similar window (w2) around another peak (p2). This is done for different positions of said windows. The distance (k) between the windows (37,38) for which the correlation functions most resemble each other is the distance representing the payload.

Abstract: The invention relates to a method of embedding a watermark W in an information signal P, to a corresponding arrangement for embedding a watermark W in an information signal P, to an information signal with an embedded watermark, and to a storage medium 50 having stored thereon an information signal P with an embedded watermark W. The watermark is embedded in the information signal by deriving sub-patterns Wi from said watermark pattern W, wherein the energy spectrum concentration of each sub-pattern Wi has a dominent orientation. The local weight factors &lgr;(P) for said watermark sub-patterns Wi are determined based on the local energy spectrum of the information signal P in said dominent orientation. Said watermark sub-patterns Wi are locally weighted using said determined local weight factors &lgr;(P). Finally, the locally weighted watermark sub-patterns (Wi) are added to the information signal P.

Abstract: Method and apparatus for providing generational copy control of a video signal. A digital video signal contains content information, first supplemental information and second supplemental information. The first supplemental information is represented by a watermark pattern, the second by a control pattern. Copying of the content information is only permitted if a predetermined combination of the first and second supplemental information is present. Pseudo-sync pulses are added to a blanking interval of an analog video signal converted from a digital video signal, the pulses representing the second supplemental information.

Abstract: Most watermarking schemes are not resistant to geometric distortions of a watermarked image, because such manipulations destroy the correlation between the original watermark and the watermark in the manipulated image. In order to restore the correlation, a suspect image (Q) is analyzed (6) for the presence of a repeated data pattern. If such a pattern is found, it is concluded that the image has been watermarked by “tiling” a small-sized watermark pattern over the extent of the image. The actual detection of whether the watermark is a given watermark W is subsequently performed by determining the periodicity of the pattern found in the suspect image, and processing (9) the suspect image so as to match the periodicity of the processed image with the given periodicity of the watermark to be detected. If the suspect image indeed includes the given watermark W, the geometric manipulation is thereby undone and a conventional watermark detector (3) will signify this accordingly.

Abstract: The invention relates to a method and a system (100) for embedding extra information in an input signal (101). Groups of one or more candidate frames in the input signal (101) are associated with respective portions of the extra information. Each group is edited in dependence on its associated respective portion, for example by deleting it to represent a zero bit in the respective portion and duplicating it to represent a one. The invention further relates to a method and system (200) for decoding extra information embedded in an input signal (201) by comparing it with an original input signal (204) and decoding the differences into the extra information. For example, missing groups of candidate frames are decoded into a zero bit, and duplicated candidate frames are decoded into a one bit.

Abstract: Given multimedia content with two (possibly different types of) watermarks, the naive way of retrieving both messages is to apply the two detectors independently. In case that geometry retrieval (e.g. undoing scaling) is an integral part of watermark detection, this implies that geometry retrieval is duplicated in both detections. In particular, the combined detection may be unnecessarily complex. The invention provides a solution for this problem. A first watermark detector makes the geometry retrieval parameters available to the second watermark detector, thereby reducing the complexity of the combined detection.

Abstract: Data is hidden in an information signal by encoding payload in to relative positions and/or polarities of multiple (possibly equal) embedded watermarks. The payload is retrieved by computing the correlation between the watermark(s) and the signal as a function of the position. The distance between peaks of the correlation function represents the payload. In order to precisely detect said distance, even if the peaks are smeared, the correlation function in a window (w1) around one peak (p1) is compared with the correlation function in a similar window (w2) around another peak (p2). This is done for different positions of said windows. The distance (k) between the windows (37,38) for which the correlation functions most resemble each other is the distance representing the payload.