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Hi Paul,</div>
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A way you can justify your suggestion is to repeat the various tests against astronomical data as described in
<a href="http://adsabs.harvard.edu/abs/2010PASP..122.1065P" data-outlook-id="de8ed693-596c-453f-a958-d3d4144c871a">
http://adsabs.harvard.edu/abs/2010PASP..122.1065P</a> and <a href="http://adsabs.harvard.edu/abs/2009PASP..121..414P" data-outlook-id="d64dbe5a-9eb3-4c1a-8e3c-fb8278becb4b">
http://adsabs.harvard.edu/abs/2009PASP..121..414P</a></div>
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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,
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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.</div>
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Rob</div>
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—</div>
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<div class="ms-outlook-mobile-reference-message skipProofing">On 10/27/25, 9:52 AM, "fitsbits" wrote:</div>
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<p dir="ltr" class="mc-ip-hide" style="text-align: center;"><span style="font-family: Helvetica, Arial, sans-serif; font-size: 12px; color: red;"><b>External Email</b></span></p>
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<div dir="ltr" class="ms-outlook-mobile-reference-message skipProofing">Yes, the suggestion is to extend the set of algorithms to include the lossless (fpzip) and lossy (fpz) algorithms.</div>
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<div dir="ltr" class="ms-outlook-mobile-reference-message skipProofing"> -- Paul</div>
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<div dir="ltr" class="gmail_attr">On Mon, Oct 27, 2025 at 11:34 AM peter teuben via fitsbits <<a href="mailto:fitsbits@listmgr.nrao.edu" data-outlook-id="5f3900bd-1a21-4aa3-b343-8d2a5e9ffb93">fitsbits@listmgr.nrao.edu</a>> wrote:</div>
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<p class="gmail_quote">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?</p>
<p class="gmail_quote">I get worried if we encode (compression) algorithms in order to decode FITS files.</p>
<p class="gmail_quote"> - peter</p>
<div class="gmail_quote">On 10/27/25 11:13, Barrett, Paul via fitsbits wrote:</div>
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<div dir="ltr" class="gmail_quote">I would like to suggest that FITS add the <a href="https://computing.llnl.gov/projects/fpzip" target="_blank" data-outlook-id="f756f976-43de-4941-9fc8-7f432de0b8d7">
fpzip</a> floating point compression algorithm to the FITS standard. fpzip is primarily designed for lossless compression but also has a provision for lossy compression.</div>
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<div dir="ltr" class="gmail_quote">I will be adding it to FITSFiles.jl, a pure Julia implementation of the FITS standard.</div>
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<div dir="ltr" class="gmail_quote"> -- Paul</div>
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<div dir="ltr" class="gmail_quote">--</div>
<div dir="ltr" class="gmail_signature">Paul Barrett, PhD</div>
<div dir="ltr" class="gmail_signature">Department of Physics</div>
<div dir="ltr" class="gmail_signature">The George Washington University</div>
<div dir="ltr" class="gmail_signature">Washington, DC 20052</div>
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