A method and apparatus for image compression using temporal and resolution
layering of compressed image frames, and which provides encryption and
watermarking capabilities. In particular, layered compression allows a
form of modularized decomposition of an image that supports flexible
encryption and watermarking techniques. Using layered compression, the
base layer and various internal components of the base layer can be used
to encrypt a compressed layered movie data stream. By using such a
layered subset of the bits, the entire picture stream can be made
unrecognizable by encrypting only a small fraction of the bits of the
entire stream. A variety of encryption algorithms and strengths can be
applied to various portions of the layered stream, including enhancement
layers. Encryption algorithms or keys can be changed at each slice
boundary as well, to provide greater intertwining of the encryption and
the picture stream. Watermarking tracks lost or stolen copies back to the
source, so that the nature of the method of theft can be determined and
so that those involved in a theft can be identified. Watermarking
preferably uses low order bits in certain coefficients in certain frames
of a layered compression movie stream to provide reliable identification
while being invisible or nearly invisible to the eye. An enhancement
layer can also have its own unique identifying watermark structure.