diff options
Diffstat (limited to 'lib/stwcs/updatewcs/det2im.py')
| -rw-r--r-- | lib/stwcs/updatewcs/det2im.py | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/lib/stwcs/updatewcs/det2im.py b/lib/stwcs/updatewcs/det2im.py new file mode 100644 index 0000000..fe683b4 --- /dev/null +++ b/lib/stwcs/updatewcs/det2im.py @@ -0,0 +1,200 @@ +from __future__ import division # confidence high + +import time +import pyfits +from stsci.tools import fileutil +import utils + +import logging +logger = logging.getLogger('stwcs.updatewcs.Det2IM') + +class DET2IMCorr(object): + """ + Stores a small correction to the detector coordinates as a d2imarr + extension in the science file. + + Notes + ----- + For the case of ACS/WFC every 68th column is wider than the rest. + To compensate for this a small correction needs to be applied to the + detector coordinates. We call this a detector to image transformation. + The so obtained image coordinates are the input to all other distortion + corrections. The correction is originally stored in an external + reference file pointed to by 'D2IMFILE' keyword in the primary header. + This class attaches the correction array as an extension to the science + file with extname = `d2imarr`. + + Other keywords used in this correction are: + + `AXISCORR`: integer (1 or 2) - axis to which the detector to image + correction is applied + + `D2IMEXT`: string = name of reference file which was used to create + the lookup table extension + + `D2IMERR`: float, optional - maximum value of the correction + + """ + 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. + """ + logger.info("\n\tStarting Det2IM Correction: %s" % time.asctime()) + try: + assert isinstance(fobj, pyfits.HDUList) + except AssertionError: + logger.exception('\n\tInput must be a pyfits.HDUList object') + raise + + 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: + logger.warning('\n\tDET2IM correction expects the reference file to have \ + an EXTNAME keyword of value "DX" or "DY", EXTNAMe %s detected' % direction) + return None + except KeyError: + logger.exception("\n\tD2IMFILE %s is missing EXTNAME keyword. Unable to determine axis \ + to which to apply the correction." % 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) + |