HDF 4.0 (and later releases) supports a low-level compression interface, which allows any data-object to be compressed using a variety of algorithms.
Currently only three compression algorithms are supported: Run-Length Encoding (RLE), adaptive Huffman, and an LZ-77 dictionary coder (the gzip 'deflation' algorithm). Plans for future algorithms include an Lempel/Ziv-78 dictionary coding, an arithmetic coder and a faster Huffman algorithm.
- HDF 4.0 (and later releases) supports n-bit compression for SDSs.
- HDF 4.0 (and later releases) supports RLE (Run Length Encoding), IMCOMP, and JPEG compression for raster images.
New with HDF 4.1 is support for "chunking" and "chunking with compression". Data chunking allows an n-dimensional SDS or GR image to be stored as a series of n-dimensional chunks. See the HDF User's Guide for more information.
With HDF4.2r0, HDF supports SZIP compression. For further information regarding it, see SZIP Compression in HDF Products.
NOTE: Compression and chunking are limited to fixed sized datasets. You cannot compress or chunk a dataset that has unlimited dimensions.