[fitsbits] start of Public Comment Period on compressed FITS image and tables

[Mandel, Eric]

>
> How interesting.  I'm not sure if your experience argues for or
> against the incorporation of tile compression in the standard.


For me as a developer, tiled compression already is part of the standard:
the very first email we got after announcing release 1 of JS9 (October
2014) was a complaint that it did not  handle rice-compressed tiled
images.  I eventually came to the conclusion that cfitsio *was* the
practical standard, at least for anyone trying to write software for the
community at large. I know Bill Joye has spent a lot of time implementing
tiled compression in DS9 (which does not use cfitsio), just because of
widespread demand.

So in the end I guess I would have to recommend official adoption of
widely-used conventions such as tiled compression, because at least they
will get documented properly. It may be that we have to recognize the
reality of this path: conventions become de facto standards by wide
adoption, and eventually need to be recognized as such.

Eric

On Wed, Jun 24, 2015 at 12:00 PM, Mark Taylor <m.b.taylor at bristol.ac.uk>
wrote:

> On Wed, 24 Jun 2015, Mandel, Eric wrote:
>
> > >
> > > Yes the implementation of this proposed addition to the standard
> > > is all there in CFITSIO, but that can't be used directly by
> > > non-C-friendly languages such as java, javascript, and who knows
> > > what future platforms might arise.  That means that for instance
> > > browser-based FITS image viewers which currently can display any
> > > legal FITS image would likely, following incorporation of this
> > > convention to the standard, find themselves unable to deal with
> > > some standard FITS image data if they are unable to afford
> >
> > considerable extra implementation effort.
> >
> >
> > For the record, this is not strictly true. The JS9 project (DS9 in the
> > browser, see http://js9.si.edu) can read any FITS file (subject to
> browser
> > memory limitations, along with my coding skills), because we implement
> FITS
> > support by compiling cfitsio to optimized javascript using emscripten (
> > http://kripken.github.io/emscripten-site/). One should be able to drag
> and
> > drop any FITS data file onto the JS9 web site to display the image. In
> > fact, there is a lot of work going on in the Web world to make C
> available
> > inside the browser (cf. the latest developments at
> > http://www.2ality.com/2015/06/web-assembly.html). So I think the Web
> world
> > will be able to follow whatever FITS standards we agree on, so long as
> > there are C implementations to support those standards.
> >
> > But as Mark points out, it's a different question whether one wants to
> make
> > the FITS standard so complicated that only a relatively few C/C++ library
> > implementations can claim completeness. One big reason we moved to
> > emscripten and cfitsio is that it was way too much work to implement
> tiled
> > compression in the javascript FITS library we wrote for initial JS9
> > implementation.
>
> How interesting.  I'm not sure if your experience argues for or
> against the incorporation of tile compression in the standard.
>
> --
> Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
> m.b.taylor at bris.ac.uk +44-117-9288776  http://www.star.bris.ac.uk/~mbt/
>
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