[gnuastro-devel] [task #14147] Use WCS coordinates in Arithmetic

[Mohammad Akhlaghi]

URL:
  <http://savannah.gnu.org/task/?14147>

                 Summary: Use WCS coordinates in Arithmetic 
                 Project: GNU Astronomy Utilities
            Submitted by: makhlaghi
            Submitted on: Tue 06 Sep 2016 01:49:23 AM JST
         Should Start On: Tue 06 Sep 2016 12:00:00 AM JST
   Should be Finished on: Tue 06 Sep 2016 12:00:00 AM JST
                Category: Arithmetic
                Priority: 5 - Normal
              Item Group: Enhancement
                  Status: Postponed
                 Privacy: Public
        Percent Complete: 0%
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
                  Effort: 0.00

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Details:

After several warpings and croppings (which are necessary during data
processing) the sizes of each output might be slightly different (by a pixel
for example). So while the WCS coordinates (which are floating points) are
accurate, ImageCrop will not work and will complain about the size of the
images.

So Upon reading each image operand, Arithmetic should have an operating mode
where it will warp the newly read input into the grid of the image in memory
(based on the WCS information, or a given WCS information). This way it can do
its operations accurately, irrespective of what size the actual images are.
This can also be used in creating deep images later.

In the core, a job like this should actually be done by ImageWarp too: so
instead of a warping Matrix, you can give ImageWarp a reference FITS image and
it will warp the input image to the WCS coordinates of the input image. So we
should be working on a library function for this job for all utilities to
benefit from.




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