Patent ID: 7302577

Claim:
An encoding data processing apparatus for generating at least one marked copy of an original item of material by introducing one of a predetermined set of code words into a copy of said material item, said code word comprising a plurality of coefficients formed from one of pseudo-randomly and randomly distributed numbers, said apparatus comprising: a code word generator configured to provide said code word having said plurality of code word coefficients, an encoder processor configured to combine the code word coefficients with said material item, and an adaptation processor including a pre-processor configured to adapt the magnitude of the material item samples in accordance with a mapping function before the code word coefficients are combined with the material item samples, and a post-processor coupled to the encoder and configured to adapt the magnitude of the material item samples with which said code word coefficients have been combined in accordance with an inverse mapping function, the adaptation of the material item samples before and after said code word coefficients are combined therewith being arranged to adapt the strength of said code word coefficients with respect to said material item samples in accordance with a relative sensitivity of said material item samples to carry said code word coefficients, said inverse mapping function being complementary to the mapping function performed by the post-processor, wherein said mapping function provides a non-linear relationship between the magnitude of the material signal samples received and the adapted magnitude of the material signal samples.