Herb Caen, a popular columnist for the San Francisco Chronicle, recently
quoted a Voice of America press release as saying that it was
reorganizing in order to "eliminate duplication and redundancy. " This
quote both states a goal of data compression and illustrates its common
need: the removal of duplication (or redundancy) can provide a more
efficient representation of data and the quoted phrase is itself a
candidate for such surgery. Not only can the number of words in the
quote be reduced without losing informa- tion, but the statement would
actually be enhanced by such compression since it will no longer
exemplify the wrong that the policy is supposed to correct. Here
compression can streamline the phrase and minimize the em- barassment
while improving the English style. Compression in general is intended to
provide efficient representations of data while preserving the essential
information contained in the data. This book is devoted to the theory
and practice of signal compression, i. e., data compression applied to
signals such as speech, audio, images, and video signals (excluding
other data types such as financial data or general- purpose computer
data). The emphasis is on the conversion of analog waveforms into
efficient digital representations and on the compression of digital
information into the fewest possible bits. Both operations should yield
the highest possible reconstruction fidelity subject to constraints on
the bit rate and implementation complexity.