DrizzlePac Release Notes

The version of DrizzlePac can be identified using

> python
>>> import drizzlepac
>>> drizzlepac.__version__

The following notes provide some details on what has been revised for each version in reverse chronological order (most recent version at the top of the list).

DrizzlePac v2.2.3 (not yet released)

  • Updated links in the documentation to point to latest drizzlepac website and online API documentation.
  • Code cleanup.
  • Updated C code to be more compatible with latest numpy releases in order to reduce numerous compile warnings.
  • Updated documentation to eliminate (at this moment) all sphinx documentation generation warnings.
  • Moved 'release_notes.rst' to 'CHANGELOG.rst' in the top-level directory.

DrizzlePac v2.2.2 (18-April-2018)

  • Fixed a bug in TweakReg introduced in v2.2.0 due to which, when TweakReg is run from the interpreter, the code may crash when trying to interpret input files.

DrizzlePac v2.2.1 (12-April-2018)

  • Fixed problems with processing WFPC2 data provided by the archive. User will need to make sure they run updatewcs on all input WFPC2 data before combining them with astrodrizzle.

Drizzlepac v2.2.0 (11-April-2018)

  • Implemented a major refactor of the project directory structure. Building no longer requires d2to1 or stsci.distutils. Drizzlepac’s release information (i.e. version, build date, etc) is now handled by relic. See https://github.com/spacetelescope/relic
  • Added basic support for compiling Drizzlepac’s C extensions under Windows.
  • Documentation is now generated during the build process. This ensures the end-user always has access to documentation that applies to the version of drizzlepac being used.
  • Swapped the effect of setting configobj to None or 'defaults' in AstroDrizzle and TweakReg. When calling one of these tasks with configobj parameter set to None, values for the not-explicitly-specified parameters should be set to the default values for the task. When configobj is set to 'defaults' not-explicitly-specified parameters will be loaded from the ~/.teal/astrodrizzle.cfg or ~/.teal/tweakreg.cfg files that store latest used settings (or from matching configuration files in the current directory). See https://github.com/spacetelescope/drizzlepac/pull/115 for more details.

Drizzlepac v2.1.22 (15-March-2018)

  • Changed the definition of Megabyte used to describe the size of the buffer for create median step (combine_bufsize). Previously a mixed (base-2 and base-10) definition was used with 1MB = 1000x1024B = 1024000B. Now 1MB is defined in base-2 (MiB) as 1MB = 1024x1024B = 1048576B.
  • Redesigned the logic in createMedian step used to split large single_sci images into smaller chunks: new logic is more straightforward and fixes errors in the old algorithm that resulted in crashes or unnecessarily small chunk sizes that slowed down createMedian step.
  • Due to the above mentioned redesign in the logic for splitting large images into smaller chunks, now overlap can be set to 0 if so desired in the minmed combine type. Also, it is automatically ignored (set to 0) for all non-minmed combine types. This will result in additional speed-up in the Create Median step.
  • Both AstroDrizzle() and TweakReg() now can be called with configobj parameter set to 'defaults' in order to indicate that values for the not-explicitly-specified parameters should be set to the default values for the task instead of being loaded from the ~/.teal/astrodrizzle.cfg or ~/.teal/tweakreg.cfg files that store latest used settings.
  • Updated documentation.

Drizzlepac v2.1.21 (12-January-2018)

  • Restore recording of correct EXPTIME value in the headers of single drizzled (“single_sci”) images. See https://github.com/spacetelescope/drizzlepac/issues/93 for more details.
  • Fixed a bug in drizzlepac due to which user provided combine_lthresh or combine_hthresh in the CREATE MEDIAN IMAGE step were not converted correctly to electrons (processing unit). This bug affected processing of WFPC2, STIS, NICMOS, and WFC3 data. See https://github.com/spacetelescope/drizzlepac/issues/94 for more details.
  • Modified print format so that scales, skew and rotations are printed with 10 significant digits while shifts are printed with 4 digits after the decimal point.

DrizzlePac v2.1.20 (07-October-2017)

DrizzlePac v2.1.19 (29-September-2017)

Drizzlepac v2.1.18 (05-September-2017)

DrizzlePac v2.1.17 (13-June-2017)

  • drizzlepac.adrizzle updated to work with numpy >=1.12 when they implemented more strict array conversion rules for math. Any input which still has INT format will be converted to a float before any operations are performed, explicitly implementing what was an automatic operation prior to numpy 1.12.

DrizzlePac v2.1.16 (05-June-2017)

  • Fixed a bug introduced in release v2.1.15 in the logic for merging WCS due to which custom WCS scale was being ignored.

DrizzlePac v2.1.15 (26-May-2017)

  • fits.io operations will no longer use memory mapping in order to reduce the number of file handles used when running either astrodrizzle or tweakreg. See issue #39 for more details.
  • Fixed bugs and improved the logic for merging WCS that is used to define astrodrizzle’s output WCS.
  • Added crpix1 and crpix2 parameters to custom WCS.

DrizzlePac v2.1.14 (28-Apr-2017)

DrizzlePac v2.1.13 (11-Apr-2017)

  • Fixed a bug due to which sky background was subtracted by astrodrizzle from the images even though skysub was set to False when MDRIZSKY was already present in input images’ headers.

DrizzlePac v2.1.12 (04-Apr-2017)

  • astrodrizzle now will run updatewcs() on newly created images when necessary, e.g., after converting WAVERED FITS to MEF format (*c0f.fits to *_c0h.fits) or after unpacking multi-imset STIS _flt files. See PR #56 for more details.
  • Fixed a bug that was preventing processing STIS image data.
  • Fixed a bug in reading user input (see issue #51).

DrizzlePac v2.1.11 (24-Mar-2017)

Bug fix release (a bug was introduced in v2.1.10).

DrizzlePac v2.1.10 (23-Mar-2017)

Some of the changes introduced in release v2.1.9 were not backward compatible. This release makes those changes backward compatible.

DrizzlePac v2.1.9 (22-Mar-2017)

Compatibility improvements with Python 3 and other STScI software packages.

DrizzlePac v2.1.8 (08-Feb-2017)

  • Drizzlepac code will no longer attempt to delete “original” (WCS key ‘O’) resulting in a decreased number of warnings (see issue #35 ).
  • Negative values are now zeroed in the ‘minmed’ step before attempting to estimate Poisson errors (see issue #22).
  • Fixed a bug in tweakreg due to incorrect matrix inversion.
  • Improved compatibility with astropy.io.fits (‘clobber’ parameter) and numpy which has reduced the number of deprecation warnings).
  • Existing static masks in the working directory are now overwritten and not simply re-used (see issue #23).
  • Corrected formula for \(\sigma\) computation in the “create median” step to convert background to electrons before computations. This bug was producing incorrect \(\sigma\) for instruments whose gain was different from one.
  • Improved astrodrizzle documentation for combine_type parameter which now also documents the formula for \(\sigma\) computation when combine_type parameter is set to 'minmed'.

DrizzlePac v2.1.6 and 2.1.7rc (15-Aug-2016)

Package maintenance release.

DrizzlePac v2.1.5 (09-Aug-2016)

Technical re-release of v2.1.4.

DrizzlePac v2.1.4 (01-Jul-2016)

The following bug fixes have been implemented:

  • tweakreg crashes when run with a single input image and a reference catalog.
  • Fixes an issue due to which tweakreg, when updating image headers, would not add ‘-SIP’ suffix to CTYPE

DrizzlePac v2.1.3 (16-Mar-2016)

  • Improved ASN input file handling.
  • astrodrizzle does not delete d2imfile anylonger allowing multiple runs of updatewcs on the same WFPC2 image, see Ticket 1244 for more details.
  • Allow exclusion regions in tweakreg to be in a different directory and allow relative path in exclusion region file name.
  • Improved handling of empty input image lists.
  • tweakreg bug fix: use absolute value of polygon area.

DrizzlePac v2.1.2 (12-Jan-2016)

  • runastrodriz moved to drizzlepac from acstools and wfc3tools packages.
  • Improved logic for duplicate input detection.
  • Improved logic for handling custom WCS parameters in astrodrizzle.
  • Compatibility improvements with Python 3.

DrizzlePac v2.1.1

Available under SSBX/IRAFX starting: Nov 17, 2015

This release includes the following bug fixes:

  • Resolved order of operation problems when processing WFPC2 data with DGEOFILEs.
  • The conversion of the WFPC2 DGEOFILE into D2IMFILE is now incorporated into STWCS v1.2.3 (r47112, r47113, r47114) rather than a part of astrodrizzle. This requires users to run updatewcs first, then astrodrizzle/tweakreg will work with that WFPC2 data seamlessly (as if they were ACS or WFC3 data).
  • Compatibility improvements with Python 3.

DrizzlePac(astrodrizzle) v2.1.0

Available under SSBX/IRAFX starting: Nov 2, 2015

This version builds upon the major set of changes implemented in v2.0.0 by not only fixing some bugs, but also cleaning up/changing/revising some APIs and docstrings. The complete list of changes includes:

  • [API Change] The ‘updatewcs’ parameter was removed from both the astrodrizzle and tweakreg interactive TEAL interfaces. The ‘updatewcs’ parameter can still be used with the Python interface for both the astrodrizzle. astrodrizzle``() and ``tweakreg. Call the stwcs.updatewcs.updatewcs() function separately before running astrodrizzle or tweakreg.
  • [API Change] The stand-alone interface for the blot routine (ablot.blot()) has been revised to work seamlessly with astrodrizzle-generated products while being more obvious how to call it correctly. The help file for this task was also heavily revised to document all the input parameters and to provide an example of how to use the task.
  • [API Change] Coordinate transformation task (pixtopix/pixtosky/skytopix) interfaces changed to be more consistent, yet remain backward-compatible for now.
  • Both astrodrizzle and tweakreg now return an output CD matrix which has identical cross-terms indicating the same scale and orientation in each axis (an orthogonal CD matrix). This relies on a revision to the stwcs.distortion.utils.output_wcs() function.
  • The user interfaces to all 3 coordinate transformation tasks now use ‘coordfile’ as the input file of coordinates to transform. The use of ‘coords’ has been deprecated, but still can be used if needed. However, use of ‘coordfile’ will always override any input provided simultaneously with ‘coords’ parameter. Help files have been updated to document this as clearly as possible for users.
  • User-provided list of input catalogs no longer needs to be matched exactly with input files. As long as all input images are included in input catalog list in any order, tweakreg will apply the correct catalog to the correct file.
  • tweakreg has been updated to correctly and fully apply source selection criteria for both input source catalogs and reference source catalogs based on fluxmin, fluxmax and nbright for each.
  • All use of keyword deletion has been updated in drizzlepac (and fitsblender) to avoid warnings from astropy.
  • All 3 coordinate transformation tasks rely on the input of valid WCS information for the calculations. These tasks now warn the user when it could not find a valid WCS and instead defaulted to using a unity WCS, so that the user can understand what input needs to be checked/revised to get the correct results.
  • Exclusion/inclusion region files that can be used with tweakreg can now be specified in image coordinates and sky coordinates and will only support files written out using DS9-compatible format.
  • The filename for ‘final_refimage’ in astrodrizzle and ‘refimage’ in tweakreg can now be specified with OR without an extension, such as ‘[sci,1]’ or ‘[0]’. If no extension is specified, it will automatically look for the first extension with a valid HSTWCS and use that. This makes the use of this parameter in both place consistent and more general than before.
  • The reported fit as written out to a file has been slightly modified to report more appropriate numbers of significant digits for the results.
  • Use of astrolib.coords was removed from drizzlepac and replaced by use of astropy functions instead. This eliminated one more obsolete dependency in our software.
  • Code was revised to rely entirely on astropy.wcs instead of stand-alone pywcs.
  • Code was revised to rely entirely on astropy.io.fits instead of stand-alone pyfits.
  • Added photeq task to account for inverse sensitivity variations across detector chips and/or epochs.
  • WFPC2 data from the archive with DGEOFILE reference files will now need to be processed using stwcs.updatewcs before running them through astrodrizzle or tweakreg. This update converts the obsolete, unsupported DGEOFILE correction for the WFPC2 data into a D2IMFILE specific for each WFPC2 observation, then uses that to convert the WCS based on the new conventions used for ACS and WFC3.

This set of changes represents the last major development effort for DrizzlePac in support of HST. Support of this code will continue throughout the lifetime of HST, but will be limited primarily to bug fixes to keep the code viable as Python libraries used by DrizzlePac continue to develop and evolve with the language.

DrizzlePac v2.0.0 Release Notes

** Available under SSBX/IRAFX starting:** Aug 4, 2014

This version encompasses a large number of updates and revisions to the DrizzlePac code, including the addition of new tasks and several parameter name changes. The scope of these changes indicates the level of effort that went into improving the DrizzlePac code to make it easier and more productive for users. The most significant updates to the DrizzlePac code include:

  • The Python code has been updated to work identically (without change) under both Python 2.7 and Python 3.x.
  • Implementing sky matching, a new algorithm for matching the sky across a set of images being combined by astrodrizzle.
  • Updating tweakreg to now align full mosaics where some images may not overlap others in the mosaic.
  • Added the option to write out single drizzle step images as compressed images (to save disk space for large mosaics, and I/O time for single drizzle step).
  • Improved tweakreg residual plots visually while allowing them to be written out automatically when tweakreg gets run in non-interactive mode.
  • Renamed parameters in tweakreg and imagefind to eliminate name clashes.
  • Added option to select sources based on sharpness/roundness when tweakreg searches for sources.
  • Added support for exclusion and inclusion regions arbitrary shape/size when tweakreg searches for sources.
  • Added a full set of source detection parameters for reference image to support multi-instrument alignment in tweakreg.
  • Added support for new (simpler, more robust) ACS calibration of time-dependent distortion.
  • A full 6-parameter general linear fit can now be performed using tweakreg, in addition to shift and rscale.
  • Cleaned up logic for sky-subtraction: user can now turn off sky-subtraction with skysub=no, and still specify a user-defined sky value as the skyuser keyword. This will reduce(eliminate?) the need to manually set MDRIZSKY=0.

In addition to these major updates/changes, numerous smaller bugs were fixed and other revisions were implemented which affected a small portion of the use cases, such as:

  • headerlet code now accepts lists of files to be updated.
  • source sky positions (RA and Dec) now included in match file.
  • DQ flags can now be taken into account when performing source finding in tweakreg.
  • all intermediate files generated by astrodrizzle will now be removed when using ‘clean’=’yes’.
  • a problem was fixed that caused createMedian to crash where there were no good pixels in one of the images (when they did not overlap).
  • interpretation of shiftfile now improved to handle arbitrarily-long filenames, rather than being limited to 24 character filenames.
  • documentation has been updated, sometimes with a lot more extensive descriptions.

This version of DrizzlePac also requires use of the latest release version of astropy primarily for WCS and FITS I/O support.

DrizzlePac(astrodrizzle) v1.1.16

Publicly Released through PyPI: Mar 27, 2014

Available under SSBX/IRAFX starting: Mar 13, 2014

  • Support for WFPC2 GEIS input images improved to correctly find the associated DQ images.
  • Static mask files created for all chips in an image now get deleted when using the ‘group’ parameter to only drizzle a single chip or subset of chips.
  • Fixed problem caused by changes to stsci.tools code so that drizzlepac will reference the correct extensions in input images.

DrizzlePac(astrodrizzle) v1.1.15(30-Dec-2013)

Publicly Released through PyPI: Jan 14, 2014

Available under SSBX/IRAFX starting: Jan 6, 2014

Bug fixes

  • Files created or updated by drizzlepac, fitsblender, or STWCS tasks, e.g. tweakreg or apply_headerlet, will now ensure that the NEXTEND keyword value correctly reflects the number of extensions in the FITS file upon completion.

DrizzlePac(astrodrizzle) v1.1.14dev(21-Oct-2013)

Installed in OPUS: Dec 11, 2013

Available starting: Oct 28, 2013

Bug fixes

  • DQ arrays in input images now get updated with cosmic-ray masks computed by astrodrizzle when run with the parameter in_memory=True. This restored the cosmic-ray masks detected during pipeline processing.

DrizzlePac(astrodrizzle) v1.1.13dev(11-Oct-2013) in IRAFX

available starting: Oct 21, 2013

  • tweakreg can now be run in ‘batch’ mode. This allows the user to generate plots and have them saved to disk automatically without stopping processing and requiring any user input.

DrizzlePac(astrodrizzle) v1.1.12dev(05-Sep-2013) in IRAFX

available starting: Sept 9, 2013

This version fixed a couple of bugs in astrodrizzle; namely,

  • Logic was updated to support pixfrac = 0.0 without crashing. Ths code will now automatically reset the kernel to ‘point’ in that case.
  • astrodrizzle now forcibly removes all OPUS WCS keywords from drizzle product headers.
  • Default rules for generating drizzle product headers (as used in the archive) were modified to add definitions for ‘float_one’, ‘int_one’, ‘zero’ that generate output values of 1.0, 1, and 0 (zero) respectively for use as keyword values. This allows the LTM* rules to replace ‘first’ with ‘float_one’ so that the physical and image coordinates for drizzle products are consistent.

Additionally, changes were made to STWCS for reprocessing use:

  • Problems with using apply_headerlet_as_primary() from the STWCS package on WFPC2 data have been corrected in this revision.

DrizzlePac(astrodrizzle) v1.1.11dev(05-Jul-2013) in IRAFX

Available starting: July 15, 2013

  • AstroDrizzle now can process all STIS data without crashing.

DrizzlePac(astrodrizzle) v1.1.10dev(06-Feb-2013) in IRAFX

available starting: May 6, 2013

  • The output drizzle image header no longer contains references to D2IM arrays. This allows tweakreg to work with drizzled images as input where 2-D D2IM corrections were needed.
  • Deprecated references to PyFITS .has_key() methods were also removed from the entire package, making it compatible with PyFITS 3.2.x and later.

DrizzlePac(astrodrizzle) v1.1.8dev(06-Feb-2013) in IRAFX

available starting: Feb 11, 2013

  • Fixed a bug in astrodrizzle which caused blot to raise an exception when using ‘sinc’ interpolation.
  • Cleaned up the logic for writing out the results from the pixtopix, pixtosky, and skytopix tasks to avoid an Exception when a list of inputs are provided and no output file is specified.
  • A new parameter was added to the tweakback task to allow a user to specify the value of WCSNAME when updating the FLT images with a new solution from a DRZ image header.
  • Code in tweakback for updating the header with a new WCS will now automatically generate a unique WCSNAME if the there is a WCS solution in the FLT headers with the default or user-defined value of WCSNAME.

DrizzlePac(astrodrizzle) v1.1.7dev(18-Dec-2012) in IRAFX

available starting: Feb 4, 2013

  • Updated astrodrizzle to work with input images which do not have WCSNAME defined. This should make it easier to support non-HST input images in the future.
  • cleared up confusion between flux parameters in imagefindpars and catalog inputs in tweakreg.
  • turned of use of fluxes for trimming input source catalogs when no flux column can be found in input source catalogs.

DrizzlePac(astrodrizzle) v1.1.7dev(18-Dec-2012) in IRAFX

available starting: Dec 10, 2012

  • Update tweakreg 2d histogram building mode to correctly find the peak when all the inputs match with the same offset (no spurious sources in either source catalog).
  • Fixed a bug so that Ctrl-C does not cause an exception when used while tweakreg is running.
  • revised the source finding logic to ignore sources near the image edge, a change from how daofind works (daofind expands the image with blanks then fits anyway).
  • created a new function to apply the nsigma separation criteria to (try to) eliminate duplicate entries for the same source from the source list. It turns out daofind does have problems with reporting some duplicate sources as well. This function does not work perfectly, but works to remove nearly all (if not all) duplicates in most cases.

DrizzlePac(astrodrizzle) v1.1.7dev(8-Jan-2012) in IRAFX

available starting: Jan 14, 2013

  • Bug fixed in updatehdr module to allow shiftfiles without RMS columns to work as inputs to manually apply shifts to headers of input images.
  • Revised astrodrizzle to update WCS of all input images BEFORE checking whether or not they are valid. This ensures that all files provided as input to astrodrizzle in the pipeline have the headers updated with the distortion model and new WCS.
  • Images with NGOODPIX=0 now identified for WFC3 and WFPC2 inputs, so they can be ignored during astrodrizzle processing.
  • Replaced 2d histogram building code originally written in Python with a C function that run about 4x faster.

DrizzlePac(astrodrizzle) v1.1.6dev(5-Dec-2012) in IRAFX

available starting: Dec 10, 2012

  • tweakreg v1.1.0 source finding algorithm now runs many times faster (no algorithmic changes). No changes have been made yet to speed up the 2d histogram source matching code.
  • The ‘pixtopix’ task was updated to make the ‘outimage’ parameter optional by using the input image as the default. This required no API changes, but the help files were updated.
  • Very minor update to guard against MDRIZTAB being specified without any explicit path.
  • Update astrodrizzle to correctly report the exposure time, exposure start, and exposure end for the single drizzle products, in addition to insuring the final drizzle values remain correct.
  • astrodrizzle also includes initial changes to safeguard the C code from getting improperly cast values from the configObj(TEAL) input.

DrizzlePac(astrodrizzle) v1.1.5dev(23-Oct-2012) in IRAFX

available starting: Oct 29, 2012

  • Scaling of sky array for WFC3/IR IVM generation now correct.
  • template mask files for WFPC2 no longer generated so that WFPC2 data can now be processed using num_cores > 1 (parallel processing).
  • interpretation of the ‘group’ parameter fixed to support a single integer, a comma-separated list of integers or a single ‘sci,<n>’ value. The values correspond to the FITS extension number of the extensions that should be combined. This fix may also speed up the initialization step as more direct use of pyfits was implemented for the interpretation of the ‘group’ parameter.

DrizzlePac(astrodrizzle) v1.1.1(31-Aug-2012) in HST Archive

available starting: Sept 26, 2012

The HST Archive and operational calibration pipeline started using this version on Sept 26, 2012.

DrizzlePac(astrodrizzle) v1.1.4dev(20-Sep-2012) in IRAFX

available starting: Sept 24, 2012

  • Bug fixed to allow use of final_wht_type=IVM for processing WFPC2 data.
  • Revised Initialization processing to speed it up by using more up-to-date, direct pyfits calls.

DrizzlePac(astrodrizzle) v1.1.3(7-Sep-2012) in IRAFX

available starting: Sept 17, 2012

  • Fixed the logic so that crclean images always get created regardless of the value of the ‘clean’ parameter.

DrizzlePac(astrodrizzle) v1.1.2(5-Sep-2012) in IRAFX

available starting: Sept 10, 2012

  • Remove the restriction of only being able to process images which have WCSNAME keyword as imposed by r15631. The removal of this restriction will now allow for processing of non-updated input files with updatewcs=False for cases where no distortion model exists for the data (as required by CADC).
  • Added log statements reporting what sky value was actually used in the drizzle and blot steps

DrizzlePac(astrodrizzle) v1.1.1(30-Aug-2012) in IRAFX

available starting: Sept 3, 2012

  • Major revision to astrodrizzle allowing the option to process without writing out any intermediate products to disk. The intermediate products remain in memory requiring significantly more memory than usual. This improves the overall processing time by eliminating as much disk activity as possible as long as the OS does not start disk swapping due to lack of RAM.
  • revised to turn off ‘updatewcs’ when coeffs=False(no) so that exposures with filter combinations not found in the IDCTAB will not cause an error.

DrizzlePac(astrodrizzle) v1.0.7(21-Aug-2012) in IRAFX

available starting: Aug 27, 2012

  • Fixes problems with missing single_sci images.
  • Static mask step revised to skip updates to static mask if all pixel data falls within a single histogram bin. This avoids problems with masking out entire images, which happens if low S/N SBC data is processed with static_mask=yes.

DrizzlePac(astrodrizzle) v1.0.6(14-Aug-2012) in IRAFX

available starting: Aug 20, 2012

Use of IVM for final_wht now correct, as previous code used wrong inputs when IVM weighting was automatically generated by astrodrizzle.

DrizzlePac(astrodrizzle) v1.0.5(8-Aug-2012) in IRAFX

available starting: Aug 13, 2012

  • Completely removed the use of the TIME arrays for weighting IR drizzle products so that the photometry for saturated sources in drizzled products now comes out correct.
  • Corrected a problem with astrodrizzle which affected processing of WFPC2 data where CRPIX2 was not found when creating the output single sci image.

stsci_python v2.13 [Includes astrodrizzle v1.0.2(13-July-2012)]

available starting: Aug 3, 2012

The complete version of stsci_python can be downloaded from our download page

DrizzlePac(astrodrizzle) v1.0.1(20-June-2012)

Used in archive/pipeline starting: July 10, 2012

Pipeline and archive started processing ACS data with this version.

DrizzlePac(astrodrizzle) v1.0.0(25-May-2012)

Used in archive/pipeline starting: June 6, 2012

Pipeline and archive first started using astrodrizzle by processing WFC3 images.