[fitsbits] Adding fpzip floating point compression {External}

[Seaman, Robert Lewis - (rseaman)]

Hi Paul,

A way you can justify your suggestion is to repeat the various tests against astronomical data as described in http://adsabs.harvard.edu/abs/2010PASP..122.1065P and http://adsabs.harvard.edu/abs/2009PASP..121..414P

No matter the algorithm and the data type, Shannon’s entropy will always govern the compression ratio that can be realized. Speed is at least as important as the compression ratio. Many lossy algorithms are tuned for appearance, not to preserve derived photometry, etc.

And, I suppose, if we are still considering implementing half-precision floating point, you might want to evaluate the algorithms for those data in advance.

Rob
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On 10/27/25, 9:52 AM, "fitsbits" wrote:


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Yes, the suggestion is to extend the set of algorithms to include the lossless (fpzip) and lossy (fpz) algorithms.

 -- Paul

On Mon, Oct 27, 2025 at 11:34 AM peter teuben via fitsbits <fitsbits at listmgr.nrao.edu<mailto:fitsbits at listmgr.nrao.edu>> wrote:

I'm not quite understanding how this would be implemented. Is this a new BITPIX ?   Or does it only apply to a new extension. like how BINTABLE was done?

I get worried if we encode (compression) algorithms in order to decode FITS files.

 - peter

On 10/27/25 11:13, Barrett, Paul via fitsbits wrote:
I would like to suggest that FITS add the fpzip<https://computing.llnl.gov/projects/fpzip> floating point compression algorithm to the FITS standard. fpzip is primarily designed for lossless compression but also has a provision for lossy compression.

I will be adding it to FITSFiles.jl, a pure Julia implementation of the FITS standard.

 -- Paul


--
Paul Barrett, PhD
Department of Physics
The George Washington University
Washington, DC 20052



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