IDIFF
Section: User Commands (1)
Updated: 07-Mar-89
Index
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NAME
idiff, udiff - convert byte stream to difference stream (b[n]-[bn-1])
SYNOPSIS
idiff < original > delta
udiff < delta > original
DESCRIPTION
Used as a preprocessor for compression algorithms. Some images
(especially grayscale and RGB) compress better when the compression is
performed on the difference between adjacent bytes, rather than the
bytes themselves (savings up to 30% are common).
Use
idiff
to convert the original to a delta file, and
udiff
to restore.
There are no magic numbers or headers, so there is no good way to tell
whether a file has been "idiffed" by examining the contents.
SEE ALSO
fbm(1) for general discussion, pbm(1) for PBM routines.
BUGS
None known.
HISTORY
Copyright (c) 1989 by Michael L. Mauldin.
Permission is granted to use this program in whole or in part provided
that you do not sell it for profit and that this copyright notice is
retained unchanged.
- 07-Mar-89 Michael L. Mauldin at Carnegie Mellon University
-
Beta release (version 0.9) mlm@cs.cmu.edu
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- SEE ALSO
-
- BUGS
-
- HISTORY
-
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