DATA COMPRESSION
- Standard utilities often do not work well because of random noise,
and do not make use of the 2-D pixel correlations.
- Entropy Encoding works well because most of the
image only uses a limited dynamic range.
- ``Predictive coding'' works because the value
of one pixel tends to be similar to the surrounding pixels (limited
dynamic range needed).
- ``Predictive coding'' and Entropy Encoding together work very well.
- For lossless compression the maximum compression ratio is limited
by the data. It makes no sense to demand a particular compression ratio.
- Typical synchrotron experimental diffraction data may be
compressed by a factor of 2.5-3.5 with no loss of information.
(Less exposed data will compress more.)