Abstract: An image processing apparatus is operable to embed data into an image. The apparatus comprises a combining processor operable to introduce the data into a transform domain representation providing a plurality of sub-bands divided by spatial frequency components, and, in combination with a transform processor, to combine the data with the image in one of a transform domain form, the transform processor generating a transform domain form of the image, the data being combined with the image by the combining processor in the transform domain, and the transform processor generating a spatial domain representation of the combined image and data, or a spatial domain form of the image, the transform processor generating a spatial domain representation of the transform domain data, the data being combined with the image by the combining processor in the spatial domain.

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: An apparatus for detecting and recovering data embedded in information material, the data having been embedded in the material in a transform domain representation by arranging for the data to modulate a predetermined data sequence to form modulated data and combining the modulated data with the material. The apparatus comprises a transform processor operable to transform the material into the transform domain representation, and a correlation processor operable to correlate transform domain data symbols bearing the modulated data with a reproduced version of the predetermined data sequence to form a correlation output signal and to recover the embedded data from the correlation output signal. The correlation processor is operable to repeat the correlation for transform domain data symbols and data symbols of the predetermined data sequence for each of a plurality of start positions in the transform domain.

Abstract: A method of embedding data in material comprises the steps of:

Abstract: Material is represented by transform coefficients represented by digital numbers. A method of perceptibly watermarking the material comprises the steps of: changing representations of the said numbers according to an invertible algorithm without changing the number of bits in the said numbers; and encoding the changed n bit numbers to effect compression encoding of the material.

Abstract: A spatial domain image I produced by a source 1 is combined with watermark data Ri to produce a spatial domain watermarked image I′.

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: A data processor is operable to represent data symbols from a data source as modelled data symbols. The data source has first component data (R) and second component data (G), the first component data being related to the second component data. The data processor comprises a prediction processor operable to generate first modelled data symbols representative of the first component data symbols, by predicting each of the first component data symbols from the second component data symbols.