.. _calwebb_image2:
.. _calwebb_tso-image2:

calwebb_image2: Stage 2 Imaging Processing
==========================================

:Class: `jwst.pipeline.Image2Pipeline`
:Alias: calwebb_image2

Stage 2 imaging processing applies additional instrumental corrections and
calibrations that result in a fully calibrated individual exposure. There are
two parameter references used to control this pipeline, depending on whether the
data are to be treated as Time Series Observation (TSO). The parameter reference
is provided by CRDS and the reftype ``pars-image2pipeline``. In general, for
non-TSO exposures, all applicable steps are applied to the data. For TSO
exposures, some steps are set to be skipped by default (see the list of steps in
the table below).

The list of steps applied by the ``Image2Pipeline`` pipeline is shown in the
table below.

.. |check| unicode:: U+2713 .. checkmark

+--------------------------------------------+---------+---------+
| Step                                       | Non-TSO | TSO     |
+============================================+=========+=========+
| :ref:`background <background_subtraction>` | |check| |         |
+--------------------------------------------+---------+---------+
| :ref:`assign_wcs <assign_wcs_step>`        | |check| | |check| |
+--------------------------------------------+---------+---------+
| :ref:`flat_field <flatfield_step>`         | |check| | |check| |
+--------------------------------------------+---------+---------+
| :ref:`photom <photom_step>`                | |check| | |check| |
+--------------------------------------------+---------+---------+
| :ref:`resample <resample_step>` [1]_       | |check| |         |
+--------------------------------------------+---------+---------+

.. [1] Resampling is only performed for exposure types "MIR_IMAGE", "NRC_IMAGE", and
   "NIS_IMAGE".

Arguments
---------

The ``calwebb_image2`` pipeline has one optional argument::

  --save_bsub  boolean  default=False

If set to ``True``, the results of
the background subtraction step will be saved to an intermediate file,
using a product type of "_bsub" or "_bsubints", depending on whether the
data are 2D (averaged over integrations) or 3D (per-integration results).

Inputs
------

2D or 3D countrate data
+++++++++++++++++++++++

:Data model: `~jwst.datamodels.ImageModel` or `~jwst.datamodels.CubeModel`
:File suffix: _rate or _rateints

The input to ``Image2Pipeline`` is
a countrate exposure, in the form of either "_rate" or "_rateints"
data. A single input FITS file can be processed or an ASN file can be used,
as long as there is only one output product specified in
the association. If "_rateints" products are
used as input, each step applies its algorithm to each
integration in the exposure, where appropriate.

TSO and coronagraphic exposures are expected to use 3D data as input, to be
processed on a per-integration basis.

Outputs
-------

2D or 3D background-subtracted data
+++++++++++++++++++++++++++++++++++

:Data model: `~jwst.datamodels.ImageModel` or `~jwst.datamodels.CubeModel`
:File suffix: _bsub or _bsubints

This is an intermediate product that is only created if "--save_bsub" is set
to ``True`` and will contain the data as output from the
:ref:`background <background_subtraction>` step.
If the input is a "_rate" product, this will be a "_bsub" product, while
"_rateints" inputs will be saved as "_bsubints."

2D or 3D calibrated data
++++++++++++++++++++++++

:Data model: `~jwst.datamodels.ImageModel` or `~jwst.datamodels.CubeModel`
:File suffix: _cal or _calints

The output is a fully calibrated, but unrectified, exposure, using
the product type suffix "_cal" or "_calints", depending on the type of
input, e.g. "jw80600012001_02101_00003_mirimage_cal.fits".

2D resampled image
++++++++++++++++++

:Data model: `~jwst.datamodels.ImageModel`
:File suffix: _i2d

This is the output of the :ref:`resample <resample_step>` step and is only created
for regular direct imaging observations (not for TSO or coronagraphy 3D data sets).
The output file will use the "_i2d" product type suffix, e.g.
"jw80600012001_02101_00003_mirimage_i2d.fits". Note that this product is
intended for quick-look use only and is not passed along as input to Stage 3
processing. Calibrated, but unrectified (_cal) products are used as input to
Stage 3.

.. include:: ../references_general/pars-image2pipeline_reffile.inc