astropy.io.fits.hdu.compressed._codecs:Gzip2

Extended Summary

The gzip2 algorithm is a variation on 'GZIP 1'. In this case the buffer in the array of data values are shuffled so that they are arranged in order of decreasing significance before being compressed.

For example, a five-element contiguous array of two-byte (16-bit) integer values, with an original big-endian byte order of:

will have the following byte order after shuffling:

where A1, B1, C1, D1, and E1 are the most-significant buffer from each of the integer values.

Byte shuffling shall only be performed for integer or floating-point numeric data types; logical, bit, and character types must not be shuffled.