All, I'm new to astrophotography and just started working with FITS files. There's a tool I use to help read in exif data and use that to organize my photos for long term archiving called exiftool. Exiftool didn't have support for fits files... until I asked their developer about it this week, and Phil was awesome and implemented support to get me back up and running immediately... talk about awesome support!
Phil has been digging deeper into fits data and was wondering about some of the other variables in the exif data to expand exiftool's support for fits data:
I was trying to figure out how some of the FITS parameters related to the usual tags extracted for images. It seems that NAXIS1 (or ZNAXIS1) is typically the image width, and NAXIS2 (or ZNAXIS2) is the height. What would you think about me changing the names of these to ImageWidth and ImageHeight? These are tags that are universal across most image formats, and it could be useful to have these available for FITS images.
However, while the NAXIS1 appears to be the width in my tests, the FITS definitions indicate that might not always be true.
But this wording in the specification worries me:
NAXIS1 keyword. The value field shall contain a non-negative integer, giving the number of ASCII characters in each row of the table. This includes all the characters in the defined fields plus any characters that are not included in any field.
NAXIS2 keyword. The value field shall contain a non-negative integer, giving the number of rows in the table.
So NAXIS1 is probably not the image width if the table is ASCII (how many ASCII characters does it take to specify a pixel?). But NAXIS2 is likely the height.
Can anyone with more FITS experience help explain this in greater detail, or provide samples where NAXIS1 is used differently?
Edited by alightner, 09 March 2019 - 01:31 PM.