.. _cbctpostprocessing:

Post Processing
==================

Post Processing offers convenient cropping features for CT reconstruction volumes.
A CT volume can be cropped either circularly around the volume vertical axis or by number of pixels along volume dimensions. 

Input
-----
- CT reconstruction volume.
- X-ray projections with corresponding geometry used in the CT volume computation (see :ref:`CT Geometry <CT_Geometry>`). 

After loading both the CT volume and X-ray projections into the ImFusionSuite, select both images in the data list, right-click, and then choose ``Post Processing`` from the ``CT`` sub-menu. 

.. image:: img/ctpostprocess_launch.png

The ``Post Processing`` algorithm controller is opened and added to the algorithm dock on the left side of the ImFusionSuite GUI.

.. image:: img/ctpostprocess_params.png

Parameters
----------
In the ``Post Processing`` controller, users can adjust the following cropping parameters:  

* ``Crop radius``: This value indicates the relative radius within the range ``[0.0, 1.0]`` for cropping to the actual detector size in the y-direction. A value of ``0.0`` disables cropping. 
* ``Crop fan``: Specify the cropping mode choosing from a list of 4 available modes. 
* ``Crop lower``: Determine the number of pixels to be cropped in 3D at the lower corner of the CT volume.
* ``Crop upper``: Determine the number of pixels to be cropped in 3D at the upper corner of the CT volume.
* ``applyHUCalibration``: Enable or disable HU calibration. For more detailed parameters and usage, refer to the :ref:`Hounsfield Calibration <hounsfieldcalibration>` section. 

After configuring all the paramters, click the ``Compute`` button to apply the algorithm to the CT volume.

The MPR view will updated to display the output volume after applying ``Post Processing`` algorithm. 

.. note:: The ``Post Processing`` is an in-place and irreversible operation.