Systems and methods are described for repeatedly embedding information in
media that is recoverable by emphasizing subtle variations between the
media. In many embodiments perceptual models are used to identify
portions of the media in which the embedded information is unlikely to be
apparent to a human observer. One embodiment of the invention includes
rendering the information in the form of a media, selecting a plurality
of portions of media from the carrier media, combining at least part of
the rendered media with each of the selected portions of the carrier
media to form modified media portions, where the modifications to the
modified media portions are not apparent to a human observer and creating
a modified carrier medium using the modified media portions.