.. _sh2power:

sh2power
===================

Synopsis
--------

Compute the total power of a spherical harmonics image

Usage
--------

::

    sh2power [ options ]  SH power

-  *SH*: the input spherical harmonics coefficients image.
-  *power*: the output power image.

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

This command computes the sum of squared SH coefficients, which equals the mean-squared amplitude of the spherical function it represents.

The spherical harmonic coefficients are stored according the conventions described the main documentation, which can be found at the following link:  |br|
https://mrtrix.readthedocs.io/en/3.0.4/concepts/spherical_harmonics.html

Options
-------

-  **-spectrum** output the power spectrum, i.e., the power contained within each harmonic degree (l=0, 2, 4, ...) as a 4-D image.

Standard options
^^^^^^^^^^^^^^^^

-  **-info** display information messages.

-  **-quiet** do not display information messages or progress status; alternatively, this can be achieved by setting the MRTRIX_QUIET environment variable to a non-empty string.

-  **-debug** display debugging messages.

-  **-force** force overwrite of output files (caution: using the same file as input and output might cause unexpected behaviour).

-  **-nthreads number** use this number of threads in multi-threaded applications (set to 0 to disable multi-threading).

-  **-config key value** *(multiple uses permitted)* temporarily set the value of an MRtrix config file entry.

-  **-help** display this information page and exit.

-  **-version** display version information and exit.

References
^^^^^^^^^^

Tournier, J.-D.; Smith, R. E.; Raffelt, D.; Tabbara, R.; Dhollander, T.; Pietsch, M.; Christiaens, D.; Jeurissen, B.; Yeh, C.-H. & Connelly, A. MRtrix3: A fast, flexible and open software framework for medical image processing and visualisation. NeuroImage, 2019, 202, 116137

--------------



**Author:** J-Donald Tournier (jdtournier@gmail.com)

**Copyright:** Copyright (c) 2008-2022 the MRtrix3 contributors.

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License, v. 2.0. If a copy of the MPL was not distributed with this
file, You can obtain one at http://mozilla.org/MPL/2.0/.

Covered Software is provided under this License on an "as is"
basis, without warranty of any kind, either expressed, implied, or
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Covered Software is free of defects, merchantable, fit for a
particular purpose or non-infringing.
See the Mozilla Public License v. 2.0 for more details.

For more details, see http://www.mrtrix.org/.


