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from __future__ import division # confidence high
import pyfits
from pytools import fileutil
import utils
class DET2IMCorr(object):
def updateWCS(cls, fobj):
"""
Parameters
----------
fobj: pyfits object
Science file, for which a detector to image correction
is available
Notes
-----
Uses the file pointed to in the primary header keyword 'D2IMFILE'
to create an extension with a detector to image correction.
"""
assert isinstance(fobj, pyfits.HDUList)
d2imfile = fileutil.osfn(fobj[0].header['D2IMFILE'])
axiscorr = cls.getAxisCorr(d2imfile)
d2imerr = pyfits.getdata(d2imfile, ext=1).max()
if axiscorr == None:
new_kw = {}
else:
new_kw = {'D2IMEXT': d2imfile, 'AXISCORR': axiscorr, 'D2IMERR': d2imerr}
cls.applyDet2ImCorr(fobj,axiscorr)
cls.updatehdr(fobj, new_kw)
updateWCS = classmethod(updateWCS)
def getAxisCorr(cls, refname):
try:
direction = pyfits.getval(refname, ext=1, key='EXTNAME')
if direction == 'DX': return 1
elif direction == 'DY': return 2
else:
print '\tDET2IM correction expects the reference file to have'
print '\tan EXTNAME keyword of value "DX" or "DY"'
return None
except AttributeError:
print "\tAxis to which to apply the detector to image "
print "\tcorrection cannot be determined because the reference "
print "\tfile %s is missing a keyword EXTNAME" % refname
direction = None
return direction
getAxisCorr = classmethod(getAxisCorr)
def applyDet2ImCorr(cls,fobj, axiscorr):
binned = utils.getBinning(fobj)
hdu = cls.createDgeoHDU(fobj, axiscorr, binned)
d2imarr_ind = cls.getD2imIndex(fobj)
if d2imarr_ind:
fobj[d2imarr_ind] = hdu
else:
fobj.append(hdu)
applyDet2ImCorr = classmethod(applyDet2ImCorr)
def getD2imIndex(cls,fobj):
index = None
for e in range(len(fobj)):
try:
ename = fobj[e].header['EXTNAME']
except KeyError:
continue
if ename == 'D2IMARR':
index = e
return index
getD2imIndex = classmethod(getD2imIndex)
def createDgeoHDU(cls, fobj, axiscorr, binned=1):
d2imfile = fileutil.osfn(fobj[0].header['D2IMFILE'])
d2im_data = pyfits.getdata(d2imfile, ext=1)
sci_hdr = fobj['sci',1].header
d2im_hdr = cls.createDet2ImHdr(fobj, binned)
hdu = pyfits.ImageHDU(header=d2im_hdr, data=d2im_data)
return hdu
createDgeoHDU = classmethod(createDgeoHDU)
def createDet2ImHdr(cls, fobj, binned=1):
"""
Creates a header for the D2IMARR extension based on the
reference file recorded in D2IMFILE keyword in the primary header.
fobj - the science file
"""
d2imfile = fileutil.osfn(fobj[0].header['D2IMFILE'])
axiscorr = cls.getAxisCorr(d2imfile)
sci_hdr = fobj[1].header
data_shape = pyfits.getdata(d2imfile, ext=1).shape
naxis = pyfits.getval(d2imfile, ext=1, key='NAXIS')
kw = { 'NAXIS': 'Size of the axis',
'CRPIX': 'Coordinate system reference pixel',
'CRVAL': 'Coordinate system value at reference pixel',
'CDELT': 'Coordinate increment along axis'}
kw_comm1 = {}
kw_val1 = {}
for key in kw.keys():
for i in range(1, naxis+1):
si = str(i)
kw_comm1[key+si] = kw[key]
for i in range(1, naxis+1):
si = str(i)
kw_val1['NAXIS'+si] = data_shape[i-1]
kw_val1['CRPIX'+si] = data_shape[i-1]/2.
kw_val1['CDELT'+si] = 1./binned
kw_val1['CRVAL'+si] = (sci_hdr.get('NAXIS'+si, 1)/2. + \
sci_hdr.get('LTV'+si, 0.)) / binned
kw_comm0 = {'XTENSION': 'Image extension',
'BITPIX': 'IEEE floating point',
'NAXIS': 'Number of axes',
'EXTNAME': 'WCS distortion array',
'EXTVER': 'Distortion array version number',
'PCOUNT': 'Special data area of size 0',
'GCOUNT': 'One data group',
'AXISCORR': 'Direction in which the det2im correction is applied'}
kw_val0 = { 'XTENSION': 'IMAGE',
'BITPIX': -32,
'NAXIS': naxis,
'EXTNAME': 'D2IMARR',
'EXTVER': 1,
'PCOUNT': 0,
'GCOUNT': 1,
'AXISCORR': axiscorr
}
cdl = pyfits.CardList()
for key in kw_comm0.keys():
cdl.append(pyfits.Card(key=key, value=kw_val0[key], comment=kw_comm0[key]))
for key in kw_comm1.keys():
cdl.append(pyfits.Card(key=key, value=kw_val1[key], comment=kw_comm1[key]))
hdr = pyfits.Header(cards=cdl)
return hdr
createDet2ImHdr = classmethod(createDet2ImHdr)
def updatehdr(cls, fobj, kwdict):
"""
Update extension headers to keep record of the files used for the
detector to image correction.
"""
for ext in fobj:
try:
extname = ext.header['EXTNAME'].lower()
except KeyError:
continue
if extname == 'sci':
for kw in kwdict:
ext.header.update(kw, kwdict[kw])
else:
continue
updatehdr = classmethod(updatehdr)
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