[fitsbits] Re: Reading floating point FITS files

[Steve Allen]

On Thu 2003-11-13T10:27:08 +1100, Mark Calabretta hath writ:
> Clearly 'RGB', 'CMYK', and possibly others (e.g. 'RYB', 'YIQ', 'HSI',
> 'HSV', 'HSB', 'HLS') would be useful additions - see
> http://www.efg2.com/Lab/Library/Color/Science.htm#ColorSpaces.
>
> Typically these would be used in conjunction with BITPIX = 8.  Rather
> than three input files you'd then have one multi-dimensional image with
> an 'RGB' axis.  This seems tidier to me.

The WCS papers have covered a variety of ways to attribute meaning to
axes 1 through N of a FITS array and how to interpret CUNITn keywords.
This calls into question the interpretation of the 0th axis, by which
I mean the array data values themselves, and the BUNIT keyword.

> Seems to me that astronomy could do with something like this for storing
> pretty pictures from HST, etc.

It is not obvious how physical data values would be preserved and
documented when doing this.  Most pretty pictures have been clipped,
stretched, mapped, and/or scaled in ways that obliterate physical
meaning in the data values.

At best this seems an awful lot like reinventing TIFF in FITS.
There should be strong justifications before doing this.

--
Steve Allen          UCO/Lick Observatory       Santa Cruz, CA 95064
sla at ucolick.org      Voice: +1 831 459 3046     http://www.ucolick.org/~sla
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