[fitsbits] Re: Reading floating point FITS files

[Mark Calabretta]

On Thu 2003/11/13 19:43:11 -0800, Steve Allen wrote
in a message to: FITSbits <fitsbits at nrao.edu>

>Yes.  I suspect that most original flux data have been eradicated.
>In an astronomical image of this sort I can imagine wanting to
>compare relative fluxes and change the mapping in ways that
>this JPEG does not allow.

It's not hard to think of with ways to handle this (e.g. using the
PVi_ma keywords on an 'RGB' axis for scaling).  However, the
constituent images can always be stored separately, even in the same
FITS file.  The aim is simply to store a colour image in a standard
way, something which FITS currently cannot do!

>Yes, if you admit that geographic coordinates have properties
>sufficiently similar to celestial coordinates, via this formalism:
>http://www.remotesensing.org/geotiff/geotiff.html

Even assuming that GeoTIFF can map north up and east to the left
(I don't know), and that it can handle galactic and other celestial
coordinate systems (possibly together in one image), it still doesn't
make much sense to me that as the last step in producing a composite
image, after regridding each input FITS image onto a common coordinate
system, you have to resort to writing it out in GeoTIFF simply because
FITS can't handle colour.

Mark Calabretta
ATNF