[fitsbits] reopening of Public Comment Period on the compression conventions

[van Nieuwenhoven, Richard]

Just a remark to the "burden of supporting tile-compressed FITS images"

While the first porting of all cfitsio (C programming language)
compression code to nom-tam-fits (java programming language) was high.
My estimate is that the whole port took me ~100 hours. But at least half
of the time has gone in the outer design of the API -> clear separation
of responsibilities, removing and detecting all code duplications and
creating unidirectional code dependencies.

But now that there are two (free available) implementations of the fits
compression, the next implementation should have a much easier job,
implementing/porting them.

And as Bill stated implementations can always fall back on cfitsio and
now also on nom-tam-fits if they don't want to implement the algorithms
them self.

-Ritchie

Am 2016-01-11 um 23:25 schrieb William Pence:
> I support the suggestion by Mark Taylor and Tom McGlynn to decouple the
> Image compression and Table compression proposals so that they can each
> be considered on their own merits.  I think it makes sense to discuss
> them simultaneously during this public comment period, but when the time
> comes, the proposals can be voted on separately.
> 
> FWIW, I strongly support incorporating the Image compression proposal
> into the FITS Standard because it is an elegant and very effective
> compression technique that has been used by many astronomical projects
> for more than 25 years.
> 
> I also support the newer Table compression proposal, because I think it
> is technically mature and it's feasibility has been demonstrated by one
> major project (FACT).  While it is true that table compression is more
> complicated than image compression, and the benefits are somewhat less
> (in terms of compression ratios), and it is possible that in the future
> we may think of further improvements to the table compression technique
> (but these will not invalidate any FITS files that conform to the
> current proposal), I don't think any of these reasons are strong enough
> grounds to not approve this proposal now.
> 
> Finally, in response to Mark's remark about the burden that supporting
> tile-compressed FITS images or tables could impose on software
> developers, I would suggest a simpler solution in this case:  Just pipe
> the compressed FITS file to an external uncompression program (funpack
> in this case) and then process the output uncompressed FITS file as
> usual.  Just as it usually is not cost effective to write one's own
> software to directly read other compressed file formats (e.g., gzip or
> bzip2) most existing FITS software does not need the capability to
> directly read compressed FITS files and instead can rely on external
> uncompression utility programs to do that job for them.
> 
> -Bill


-- 
BSc Richard van Nieuwenhoven
Software Architekt

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