Realign (SPM)
=============

**Purpose.** Motion-correct ASL time series using SPM Realign (Nipype wrapper).

Inputs
------

- For each ``{asl}``: ``perf/{asl}.nii`` under the **derivatives** mirror.

Outputs
-------

- SPM realign outputs (mean images, realigned series) written in place
  following SPM’s ``write_which``/``register_to_mean`` behavior.

Configuration
-------------

=====================  ===================  ==========================================
Key                    Type / Default       Meaning
=====================  ===================  ==========================================
``quality``            float / ``0.9``      SPM quality (0–1)
``fwhm``               float / ``5``        Smoothing kernel for estimation
``register_to_mean``   bool / ``True``      Register to mean image
``jobtype``            str / ``estwrite``   ``estimate`` or ``estwrite``
``interp``             int / ``1``          Interpolation (1=trilinear)
``wrap``               list / ``[0,0,0]``   SPM wrap flags
``write_mask``         bool / ``True``      Write implicit mask
``write_which``        list / ``[2,1]``     Which images to write
=====================  ===================  ==========================================

YAML example
------------

.. code-block:: yaml

    modules:
      - name: Realign
        config:
          quality: 0.9
          fwhm: 5
          register_to_mean: true
          jobtype: estwrite