.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        Click :ref:`here <sphx_glr_download_auto_examples_06_manipulating_images_plot_negate_image.py>`     to download the full example code or to run this example in your browser via Binder
    .. rst-class:: sphx-glr-example-title

    .. _sphx_glr_auto_examples_06_manipulating_images_plot_negate_image.py:


Negating an image with math_img
===============================

The goal of this example is to illustrate the use of the function
:func:`nilearn.image.math_img` on T-maps.
We compute a negative image by multiplying its voxel values with -1.


.. code-block:: default


    from nilearn import datasets, plotting, image








Retrieve the data: the localizer dataset with contrast maps.


.. code-block:: default

    motor_images = datasets.fetch_neurovault_motor_task()
    stat_img = motor_images.images[0]








Multiply voxel values by -1.


.. code-block:: default

    negative_stat_img = image.math_img("-img", img=stat_img)

    plotting.plot_stat_map(stat_img,
                           cut_coords=(36, -27, 66),
                           threshold=3, title="t-map", vmax=9
    )
    plotting.plot_stat_map(negative_stat_img,
                           cut_coords=(36, -27, 66),
                           threshold=3, title="Negative t-map", vmax=9
    )
    plotting.show()



.. rst-class:: sphx-glr-horizontal


    *

      .. image:: /auto_examples/06_manipulating_images/images/sphx_glr_plot_negate_image_001.png
          :alt: plot negate image
          :class: sphx-glr-multi-img

    *

      .. image:: /auto_examples/06_manipulating_images/images/sphx_glr_plot_negate_image_002.png
          :alt: plot negate image
          :class: sphx-glr-multi-img






.. rst-class:: sphx-glr-timing

   **Total running time of the script:** ( 0 minutes  2.482 seconds)


.. _sphx_glr_download_auto_examples_06_manipulating_images_plot_negate_image.py:


.. only :: html

 .. container:: sphx-glr-footer
    :class: sphx-glr-footer-example


  .. container:: binder-badge

    .. image:: https://mybinder.org/badge_logo.svg
      :target: https://mybinder.org/v2/gh/nilearn/nilearn.github.io/master?filepath=examples/auto_examples/06_manipulating_images/plot_negate_image.ipynb
      :width: 150 px


  .. container:: sphx-glr-download sphx-glr-download-python

     :download:`Download Python source code: plot_negate_image.py <plot_negate_image.py>`



  .. container:: sphx-glr-download sphx-glr-download-jupyter

     :download:`Download Jupyter notebook: plot_negate_image.ipynb <plot_negate_image.ipynb>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_