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

[Maren Purves]

Michael,

(replying to Steve's messages as I find it easier to piggyback in
this case)

Steve Allen wrote:
> On Mon 2007-08-27T11:32:19 -0400, Michael Williams hath writ:
>> we're obviously speaking terribly different languages here.
> 
> We are also not managing to communicate that FITS has been in use
> for nearly 30 years.  It does work for exchanging pictures
> of the sky, catalogs of the sky, and other related information.

and the "I" stands for interchange, not for image.

> Over those 30 years there have probably been thousands of person-years
> of effort developing the software which interprets the information in

(and writes)

> the FITS files.  That may be a major point of disconnect here.

I think there is, and it is major.

>> Are the images
>> literally live pictures that were taken, or some arbitrary graphical
>> representation of data?
> 
> Yes, but in optical astronomy the first notion is usually a safe one.

this is part of the disconnect.
Even in optical astronomy you have other data in a FITS file than
a "picture" (= e.g. CCD image?). Think spectra, even light curves.

The data array do not by and in themselves have any kind of graphical
information or representation attached to them. They are data points
with coordinates, where coordinates don't even have to be spacial
(e.g. wavelength or time come to mind).

A spectrum is not a 'picture'. You can make a picture out of the
spectrum, but the detail of the information in it will be lost
independent of how you turn it into a picture.

>> 3) How do I determine what type of image manipulations are legitimate
>> for any type of image data?  Should I allow sepia toning?  Should I

why do you care? A FITS data array, even if it represents an array
of data with coordinates X and Y does not have colors associated
with it. Taking this with "beauty is in the eye of the beholder",
any color scheme will work (think false color imaging like e.g.
in infrared weather satellite imagery or NEXRAD), depending on what
the person looking at it prefers.

>> allow them to run photoshop filters on the pictures?  I mean, what,

they aren't 'pictures', they're images, and that isn't the same.

>> really is the usefulness of any manipulation on the image and what
>> are the most common techniques?
> 
> In the most general sense the answers to these questions count as the
> fulfillment of the requirements for PhD theses and refereed scientific
> literature.
> 	"If we knew what we were doing it wouldn't be research."

<g>

>> 4) What is the goal of scientists when it comes to examining
>> another's FITS files?  What kind of "information" is truly gathered
>> from the "data"?

Why do you put "data" in double quotes?

> This is science.

Taking a Schmidt plate or CCD image as an example: I may be looking
for galaxies, the next person for dark clouds and a third one for
planetary nebulae. Taking spectra, there's temperature and other
physical condition that can be derived, as well as chemistry.


If your client gave you examples (in data format, rather than in
picture format) saying "this is what we want", are you
second-guessing them?

HTH,

Maren