dsberry · November 30, 2012 15:33
diff --git a/move_wcs.py b/move_wcs.py
 #!/bin/env python

 #  Moves a simple 2D FITS image in X and Y. The output image is the same size as
 #  the input image.

 #  Usage:
 #    move_wcs.py <infile> <outfile> <xshift> <yshift>
 #
 #    <infile> = Input fits file
 #    <outfile> = Output fits file
 #    <xcen> = The shift in X pixels
 #    <ycen> = The shift in Y pixels

 #  Notes:
 #     - Requires pyast version 2.3

 import pyfits
 import sys
 import starlink.Ast as Ast
 import starlink.Atl as Atl

 #  Open the FITS file using pyfits. A list of the HDUs in the FITS file is
 #  returned.
 hdu_list = pyfits.open( sys.argv[1] )

 #  Create an object that will transfer FITS header cards between an AST
 #  FitsChan and the PyFITS header describing the primary HDU of the
 #  supplied FITS file.
 adapter = Atl.PyFITSAdapter( hdu_list[ 0 ] )

 #  Create a FitsChan and use the above adapter to copy all the header
 #  cards into it.
 fitschan = Ast.FitsChan( adapter, adapter )

 #  Get the flavour of FITS-WCS used by the header cards currently in the
 #  FitsChan. This is so that we can use the same flavour when we write
 #  out the modified WCS.
 encoding = fitschan.Encoding

 #  Read WCS information from the FitsChan. Additionally, this removes all
 #  WCS information from the FitsChan. The returned wcsinfo object
 #  is an AST FrameSet, in which the current Frame describes WCS coordinates
 #  and the base Frame describes pixel coodineates. The FrameSet includes a
 #  Mapping that specifies the transformation between the two Frames.
 wcsinfo = fitschan.read()

 #  Check that the FITS header contained WCS in a form that can be
 #  understood by AST.
 if wcsinfo == None:
   print( "Failed to read WCS information from {0}".format(sys.argv[1]) )

 #  This script is restricted to 2D arrays, so check the FITS file has 2 pixel
 #  axes (given by Nin) and 2 WCS axes (given by Nout).
 elif wcsinfo.Nin != 2 or wcsinfo.Nout != 2:
   print( "{0} is not 2-dimensional".format(sys.argv[1]) )

 #  Proceed if the WCS information was read OK.
 else:

   #  Get the lower and upper bounds of the input image in pixel indices.
   #  All FITS arrays by definition have lower pixel bounds of [1,1] (unlike
   #  NDFs). Note, unlike pyfits AST uses FITS ordering for storing pixel axis
   #  values in an array (i.e. NAXIS1 first, NAXIS2 second, etc).
   lbnd_in = [ 1, 1 ]
   ubnd_in = [ fitschan["NAXIS1"], fitschan["NAXIS2"] ]

   #  Get the required pixel shifts in X and Y.
   x0 =  float( sys.argv[3] )
   y0 =  float( sys.argv[4] )

   #  Construct a ShiftMap to do the shift.
   pixmap = Ast.ShiftMap( [ x0, y0 ] )

   # The dimensions of the output array are the same as the input array.
   lbnd_out = lbnd_in
   ubnd_out = ubnd_in

   #  Get the value used to represent missing pixel values
   if "BLANK" in fitschan:
      badval = fitschan["BLANK"]
      flags = Ast.USEBAD
   else:
      badval = 0
      flags = 0

   # Resample the data array using the above mapping.
   ( npix, out, out_var ) = pixmap.resample( lbnd_in, ubnd_in,
                                             hdu_list[0].data, None,
                                             Ast.LINEAR, None, flags,
                                             0.05, 1000, badval, lbnd_out,
                                             ubnd_out, lbnd_out, ubnd_out )

   #  Store the shifted data in the HDU.
   hdu_list[0].data = out

   #  Re-map the base Frame (i.e. the pixel coordinates Frame) so that it
   #  refers to the new data grid instead of the old one.
   wcsinfo.remapframe( Ast.BASE, pixmap )

   #  Attempt to write the modified WCS information to the primary HDU (i.e.
   #  convert the FrameSet to a set of FITS header cards stored in the
   #  FITS file). Indicate that we want to use original flavour of FITS-WCS.
   fitschan.Encoding = encoding
   fitschan.clear('Card')
   if fitschan.write( wcsinfo ) == 0 :
      print( "Failed to convert the rotated WCS to Fits-WCS" )

   #  If successfull, force the FitsCHan to copy its contents into the
   #  PyFITS header, then write the changed data and header to the output
   #  FITS file.
   else:
      fitschan.writefits()
      hdu_list.writeto(sys.argv[2],clobber=True)
	#!/bin/env python

	# Moves a simple 2D FITS image in X and Y. The output image is the same size as
	# the input image.

	# Usage:
	# move_wcs.py <infile> <outfile> <xshift> <yshift>
	#
	# <infile> = Input fits file
	# <outfile> = Output fits file
	# <xcen> = The shift in X pixels
	# <ycen> = The shift in Y pixels

	# Notes:
	# - Requires pyast version 2.3

	import pyfits
	import sys
	import starlink.Ast as Ast
	import starlink.Atl as Atl

	# Open the FITS file using pyfits. A list of the HDUs in the FITS file is
	# returned.
	hdu_list = pyfits.open( sys.argv[1] )

	# Create an object that will transfer FITS header cards between an AST
	# FitsChan and the PyFITS header describing the primary HDU of the
	# supplied FITS file.
	adapter = Atl.PyFITSAdapter( hdu_list[ 0 ] )

	# Create a FitsChan and use the above adapter to copy all the header
	# cards into it.
	fitschan = Ast.FitsChan( adapter, adapter )

	# Get the flavour of FITS-WCS used by the header cards currently in the
	# FitsChan. This is so that we can use the same flavour when we write
	# out the modified WCS.
	encoding = fitschan.Encoding

	# Read WCS information from the FitsChan. Additionally, this removes all
	# WCS information from the FitsChan. The returned wcsinfo object
	# is an AST FrameSet, in which the current Frame describes WCS coordinates
	# and the base Frame describes pixel coodineates. The FrameSet includes a
	# Mapping that specifies the transformation between the two Frames.
	wcsinfo = fitschan.read()

	# Check that the FITS header contained WCS in a form that can be
	# understood by AST.
	if wcsinfo == None:
	print( "Failed to read WCS information from {0}".format(sys.argv[1]) )

	# This script is restricted to 2D arrays, so check the FITS file has 2 pixel
	# axes (given by Nin) and 2 WCS axes (given by Nout).
	elif wcsinfo.Nin != 2 or wcsinfo.Nout != 2:
	print( "{0} is not 2-dimensional".format(sys.argv[1]) )

	# Proceed if the WCS information was read OK.
	else:

	# Get the lower and upper bounds of the input image in pixel indices.
	# All FITS arrays by definition have lower pixel bounds of [1,1] (unlike
	# NDFs). Note, unlike pyfits AST uses FITS ordering for storing pixel axis
	# values in an array (i.e. NAXIS1 first, NAXIS2 second, etc).
	lbnd_in = [ 1, 1 ]
	ubnd_in = [ fitschan["NAXIS1"], fitschan["NAXIS2"] ]

	# Get the required pixel shifts in X and Y.
	x0 = float( sys.argv[3] )
	y0 = float( sys.argv[4] )

	# Construct a ShiftMap to do the shift.
	pixmap = Ast.ShiftMap( [ x0, y0 ] )

	# The dimensions of the output array are the same as the input array.
	lbnd_out = lbnd_in
	ubnd_out = ubnd_in

	# Get the value used to represent missing pixel values
	if "BLANK" in fitschan:
	badval = fitschan["BLANK"]
	flags = Ast.USEBAD
	else:
	badval = 0
	flags = 0

	# Resample the data array using the above mapping.
	( npix, out, out_var ) = pixmap.resample( lbnd_in, ubnd_in,
	hdu_list[0].data, None,
	Ast.LINEAR, None, flags,
	0.05, 1000, badval, lbnd_out,
	ubnd_out, lbnd_out, ubnd_out )

	# Store the shifted data in the HDU.
	hdu_list[0].data = out

	# Re-map the base Frame (i.e. the pixel coordinates Frame) so that it
	# refers to the new data grid instead of the old one.
	wcsinfo.remapframe( Ast.BASE, pixmap )

	# Attempt to write the modified WCS information to the primary HDU (i.e.
	# convert the FrameSet to a set of FITS header cards stored in the
	# FITS file). Indicate that we want to use original flavour of FITS-WCS.
	fitschan.Encoding = encoding
	fitschan.clear('Card')
	if fitschan.write( wcsinfo ) == 0 :
	print( "Failed to convert the rotated WCS to Fits-WCS" )

	# If successfull, force the FitsCHan to copy its contents into the
	# PyFITS header, then write the changed data and header to the output
	# FITS file.
	else:
	fitschan.writefits()
	hdu_list.writeto(sys.argv[2],clobber=True)