Abstract: The bitstream includes digital codes representing an information signal. At least one digital code is selected. The code occupies a part of the bitstream which is to contain at least one watermark code which represents a watermark perceptible in the information signal. The selected digital code(s) are removed from the said part of the bitstream. The watermark code(s) are put in the said part of the bitstream in place of the selected code(s). The number of bits of the selected code(s) removed from the said part of the bitstream is greater than or equal to the number of bits of the said watermark code(s) put in the said part. The removed selected code(s) are appended to an end of the bitstream and/or placed in watermark user data fields created in the bitstream.

Abstract: A data processing apparatus is operable to identify one of a plurality of code words present in a watermarked version of a material item. The marked version is formed by combining each of a plurality of parts of a code word with one of a plurality of units from which the material item is comprised. The apparatus comprises a recovery processor operable to recover at least one part of the code word from a corresponding unit of the marked material item, and a correlator. The correlator is operable to generate for the marked material unit, a dependent correlation value for the part of the code word recovered from the material unit and the corresponding part of at least one of the re-generated code words from the set. A detector is operable to determine whether at least one of the code words is present in the marked material item from the dependent correlation value for the part of the code word exceeding a predetermined threshold.

Abstract: A method of controlling copying of an information signal, comprises the steps of: prior to recordal and/or transmission, applying to the information signal a substantially imperceptible modification representing copy control data including a password securely encoded according to a predetermined algorithm; upon reproduction for copying by a user, deriving (S1, S3) the copy control data from the modified information signal; comparing (S8, S9, S11, S13, S15) the derived securely encoded password with a reference password securely encoded according to a predetermined algorithm; and enabling (S5) copying of the information signal if the securely encoded password derived from the information signal and the securely encoded reference password have a predetermined relationship, otherwise disabling copying (S7). The reference password is sent to the user via a channel which is separate from a channel used to send the information signal to the user.

Abstract: A client device for use in a system having a server, the client device including: a receiving device configured to receive information material from the server, the information material containing a reversible modification providing a visually perceptible disturbing effect having been applied to the information material by using an invertible algorithm which uses values generated from one or more keys, and to receive identifying information that distinguishes the information material from other information material available from the server and condition information which defines a predetermined condition that should be met in order for the reversible modification to be reversed.

Abstract: A method of detecting a version of input data content, there being a plurality of different versions of said data content, in which: said data content is arranged as two or more segments according to a segmentation pattern; and said versions of said data content are identifiable by corresponding identification data patterns by which at least some of said segments have respective identification data; said method comprising the steps of: (i) detecting said identification data in respect of said segments of said input data content; (ii) comparing said detected identification data with said identification data patterns corresponding to said different versions of said data content; and (iii) detecting that said input data content comprises at least a contribution from a certain version of said data content if a sum of matches obtained between said detected identification data and said identification data pattern for said certain version exceeds a threshold number.

Abstract: A material distribution apparatus, comprising a material server including a data introduction processor operable to introduce data into material to be distributed with the effect that the introduced data is at least difficult to perceive in the material, and a material impairment processor operable to introduce a reversible impairment into the material. A communications network distributes the impaired material to at least one client processor which includes an impairment reversing processor operable to reverse the impairment of the material to produce client restored material.

Abstract: A method of transferring information signals representing still images, video audio and/or other data comprises sending, the information signals to a recipient apparatus or “viewer” 10 from a server 2 via a network 12. Data indicative of whether or not further data is to be embedded in the information signals is also sent either with the signals or separately. The further data is embedded in the information signals at the viewer 10 in dependence upon the indicative data. The further data is perceptible in the information signals as to degrade them.

Abstract: A watermarking system comprises an encoding data processor operable to generate at least one marked version of an original item of material by introducing one of a predetermined set of code words into a copy of the original material item. The encoding data processor is arranged to form other code words of the set by cyclically shifting a first code word. The system includes a detecting data processor operable to identify the code word in the marked material item. The detecting data processor is operable to recover the code word from the marked material item and to form a Fourier transform of the recovered code word and a Fourier transform of the first code word of the set. The data detecting processor forms correlation samples by forming an inverse transform of a combination of the recovered and the first code word. Each of the correlation value samples provides the correlation value for one of the set of code words.

Abstract: A client device for use in a system having a server, the client device including: a receiving device configured to receive information material from the server, the information material containing a reversible modification providing a perceptible disturbing effect to the information material, and to receive identifying information that distinguishes the information material from other information material available from the server and condition information which defines a predetermined condition that should be met in order for the reversible modification to be reversed; a transmission device which, in response to a user input providing enabling data which satisfies the predetermined condition, configured to transmit the identifying information and the enabling data to the server, wherein in response to the transmission of the enabling data and the identifying information, the receiving device is configured to receive a key and removing data defining an algorithm for removing the perceptible effect, the removi

Abstract: Data coding apparatus in which input data having a range of possible data values and a smaller sub-range of legal data values is coded by applying a coder mapping which maps input data values in the range of possible input data values and corresponding coded data values within the range of possible data comprises means for detecting, for each coded data value, whether the coded data value lies within the sub-range of legal data values; and means for remapping a coded data value lying outside the sub-range of legal data values to an unused coded data value lying within the sub-range of legal data values.

Abstract: A recording system for applying access control processing to input data content and for recording access-controlled data content on a computer readable storage medium. The recording system includes an encryption apparatus for encrypting portions of the input data content and an access control memory device which securely stores information from which a private key of a public key/private key pair associated with a data content recording user or user group is derivable. The encryption apparatus and the access control memory device co-operate to provide access control data including content recorder access control data and default access control data. The default content access control data provides the same level of access to the input data content as the level of access available to the data content recording user/user group. A recorder is provided for recording the encrypted input data content and the content access control data on the computer readable storage medium.

Abstract: A system for watermarking and transferring watermarked material comprises a transaction server, first and second clients, first apparatus for applying a perceptible watermark to the material and second apparatus for removing the watermark. The server, clients and first and second apparatus are linked by one or more communications networks.

Abstract: Access to a data storage arrangement is provided in dependence upon a public/private key pair, the public key being held by the data storage arrangement and the private key by a removable memory device. The public key is securely held in a user directory of authorized users on the data storage arrangement, and is associated with a local version number. Another copy of the user directory is securely held by the removable memory device and is associated with an external version number. When the removable memory device is connected to the data storage arrangement to enable authentication, these version numbers are compared and the older version of the user directory is replaced with the later version. In this fashion updates to the list of authorized users can be propagated among suitably adapted devices without the use of a network.

Abstract: A system for watermarking and distributing material includes a data processing apparatus, which operates as a watermark encoder. The data processing apparatus is operable to process an original material item to form a reduced-bandwidth-version of the material item, marked with a code word from a predetermined set of code words. The data processing apparatus is operable to form an impaired version of the material item from which a marked representation of the original material item can be formed. The impaired version is formed by subtracting the reduced-bandwidth-version of the material item from a copy of the original material item. As such, the impaired version can be mass distributed, but a representation of the original material item cannot be formed without the reduced-bandwidth-version of the material item.

Abstract: A data encoding apparatus operable to encode a plurality of data blocks produces encoded data in accordance with at least one of a selectable target data quantity or a selectable target data quality.

Abstract: A watermarking system comprises an encoding data processor operable to generate at least one marked version of an original item of material by introducing one of a predetermined set of code words into a copy of the original material item. The encoding processor comprises a code word generator operable to form the code word by generating a plurality of code word coefficients, and an encoder operable to combine the code word coefficients with the material item, and an adaptation processor. The adaptation processor is operable to adapt the strength of the code word coefficients or the material item samples in accordance with a relative sensitivity of the material item samples to carry the code word coefficients. The strength of the watermark is therefore adapted in accordance with the sensitivity of the material item to carry watermark code word coefficients. As a result there is a reduced likelihood of an attacker identifying parts of the material item to which the watermark code word has been added.

Abstract: A watermarking system includes an encoding data processor operable to generate at least one marked version of an original item of material by introducing one of a predetermined set of code words into a copy of the original material item. The apparatus has a code word generator operable to provide the code word having a plurality of code word coefficients, and an encoding processor operable to combine the code word coefficients with the material. Each of the plurality of code words of the set is uniquely associated with a data word having first and second fields. Each of a set of values of the first field is represented as a first part of the code word having a first plurality of coefficients, and the second field is represented as a second part of the code word having a second plurality of coefficients.

Abstract: A detecting data processing apparatus configured to identify at least one of a plurality of code words present in a marked version of a material item. The detecting apparatus including a registration processor operable to compare the samples of the marked material item with a copy of the original material item samples. If a sample of the marked material item and the original material item differ by a comparison threshold, the registration processor replaces the compared sample of the marked material item with the corresponding sample from the original material item.

Abstract: An encoding apparatus operable to encode video data representing successive images, each image including a plurality of pixels. The apparatus includes a differential encoder arranged to encode each image as one or more predetermined image regions. Each image is being encoded as a reference value and at least one differential pixel value. The differential pixel value(s) are derived in dependence on the reference value and/or other differential pixel value(s) in accordance with an order of encoding dependency; in which, for each image region, the differential encoder is operable in a first encoding mode for a first subset of the images to encode the image region using a first order of encoding dependency and in a second encoding mode for a second, different, subset of the images to encode the image region using a second, different, order of encoding dependency.

Abstract: A watermarking system comprises an encoding data processor operable to generate at least one marked version of an original item of material by introducing one of a predetermined set of code words into a copy of the original material item. The code words are generated from a pseudo-random number generator initialised with a seed value. The seed value is used to identify the marked material item, from the code word produced from the seed value. The watermarking system also includes a detecting data processor operable to identify a particular marked copy of the material item by recovering a code word from the marked material item and correlating all code words in the set of code words with the recovered code word. The detecting data processing apparatus also includes a registration processor operable to associate samples of the original material item with corresponding samples of the marked material item to which corresponding code word coefficients may have been added.