Description:

fpack optimally compresses FITS format images and funpack restores them
to the original state.

* Integer format images are losslessly compressed using the Rice
compression algorithm.
* typically 30% better compression than GZIP
* about 3 times faster compression speed than GZIP
* about the same uncompression speed as GUNZIP

* Floating-point format images are compressed with a lossy algorithm
* truncates the image pixel noise by a user-specified amount to
produce much higher compression than by lossless techniques
* the precision of scientific measurements in the compressed image
(relative to those in the original image) depends on the selected
amount of compression