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: 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: An apparatus for embedding data in information material, the data being a plurality of data items each having a different relative importance. The apparatus comprises an encoding processor operable to encode each of said data items, and a combining processor operable to combine said encoded data items with said information material. The information material provides a limited data embedding capacity, as a result for example of the limited bandwidth of the information material itself. Each of the data items are encoded and embedded to the effect that a proportion of the limited data embedding capacity is allocated to the encoded data items in accordance with the relative importance of these data items. As such, for example, an amount of error protection given to each of the data items can be arranged in accordance with the importance of the data items, whilst still satisfying the limited data embedding capacity.