LoadFITS-v1.rst

.. algorithm::

.. summary::

.. alias::

.. properties::

Description
-----------

Load data from FITS files. A new workspace (of type :ref:`Workspace2D
<Workspace2D>`) is created for every FITS file loaded with this
algorithm, and these workspaces are added into a group workspace. The
group workspace is named as indicated in the OutputWorkspace input
property. The workspaces included in the group are named with the same
name and an appendix _1, _2, etc.

The workspaces created by this algorithm contain one spectrum per
pixel. The first spectrum correspond to the top-left corner and the
last spectrum to the bottom-right corner.

FITS header entries
###################

This algorithm interprets extension headers defined for the IMAT
instrument (ISIS facility). At a very minimum, the standard header
entries SIMPLE, BITPIX, NAXIS, NAXIS1, and NAXIS2 must be present in
the file. The current implementation only supports 2D files (FITS
images with two axes).

Child algorithms used
#####################

This algorithm uses one child algorithm:

- :ref:`algm-LoadInstrument`, which looks for a description of the
  instrument in the facilities definition file and if found reads it.
  This algorithm is used only once when loading a set of FITS file
  corresponding to the same instrument.

Usage
-----

**Example**

.. testcode:: LoadFITS

    ws_name = 'FITSws'
    FITSws = LoadFITS(Filename='FITS_small_01.fits', OutputWorkspace=ws_name)

    # A couple of standard FITS header entries
    bpp_log = 'BITPIX'
    try:
        log = ws.getRun().getLogData(bpp_log)
        print "Bits per pixel: %d" % bpp_log
    except RuntimeError:
        print "Could not find the keyword '%s' in this FITS file" % bpp_log

    axis1_log = 'NAXIS1'
    axis2_log = 'NAXIS2'
    try:
        log1 = ws.getRun().getLogData(axis1_log)
        log2 = ws.getRun().getLogData(axis2_log)
        print "FITS image size: %d x %d pixels" % (log1, log2)
        print "Number of spectra in output workspace: %d" % FITSws.getNumberHistograms()
    except RuntimeError:
        print "Could not find the keywords '%s' and '%s' in this FITS file" % (axis1_log, axis2_log)

.. testcleanup:: LoadFITS

    DeleteWorkspace(ws_name)

Output:

.. testoutput:: LoadFITS

   Bits per pixel: 16
   FITS image size: 512 x 512 pixels
   Number of spectra in output workspace: 262144
   Could not find the keywords 'NAXIS1' and 'NAXIS2' in this FITS file
.. categories::