[fitsbits] Question(s) regarding development of proprietary FITS manipulation software. . .

[Thierry Forveille]

gberz3 a écrit :
> Why would *anyone* present FITS data as images if they are
> not image data?  Why not represent it as sound?
> 
> I guess that's what I'm getting at.  What relevance does an image have
> to actual FITS data if there is no "attached" image, and what is the
> proper means by which to display said image?
> 
The issue is mostly your notion of an image, vs an astronomer's
notion of the same. To you an image is something that can be
univocally displayed on a screen or printed, while to
astronomers it is a set of values (ideally in physical units,
such as Watts per square meter per steradian) sampled on a
regular grid. There is some link between the two notions,
but not a unique one: an astronomer's image can be displayed
but not in one unique way, and the reverse transformation
if/when at all possible, requires additional information
(e.g. the physical values for a subset of the pixels) and
significant calibration work. Essentially, an astromer's
image is a richer dataset, and someone needs to decide how
to degrade that information to what a display can show.

In addition, images (in the astronomer's definition) is only
one of the data classes that can be stored in FITS.