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

    Click :ref:`here <sphx_glr_download_generated_examples_io_plot_fits-image.py>` to download the full example code
.. rst-class:: sphx-glr-example-title

.. _sphx_glr_generated_examples_io_plot_fits-image.py:


=======================================
Read and plot an image from a FITS file
=======================================

This example opens an image stored in a FITS file and displays it to the screen.

This example uses `astropy.utils.data` to download the file, `astropy.io.fits` to open
the file, and `matplotlib.pyplot` to display the image.

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

*By: Lia R. Corrales, Adrian Price-Whelan, Kelle Cruz*

*License: BSD*

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



Set up matplotlib and use a nicer set of plot parameters



.. code-block:: python


    import matplotlib.pyplot as plt
    from astropy.visualization import astropy_mpl_style
    plt.style.use(astropy_mpl_style)







Download the example FITS files used by this example:



.. code-block:: python


    from astropy.utils.data import get_pkg_data_filename
    from astropy.io import fits

    image_file = get_pkg_data_filename('tutorials/FITS-images/HorseHead.fits')







Use `astropy.io.fits.info()` to display the structure of the file:



.. code-block:: python


    fits.info(image_file)





.. rst-class:: sphx-glr-script-out

 Out:

 .. code-block:: none

    Filename: /home/docs/.astropy/cache/download/py3/2c9202ae878ecfcb60878ceb63837f5f
    No.    Name      Ver    Type      Cards   Dimensions   Format
      0  PRIMARY       1 PrimaryHDU     161   (891, 893)   int16   
      1  er.mask       1 TableHDU        25   1600R x 4C   [F6.2, F6.2, F6.2, F6.2]


Generally the image information is located in the Primary HDU, also known
as extension 0. Here, we use `astropy.io.fits.getdata()` to read the image
data from this first extension using the keyword argument ``ext=0``:



.. code-block:: python


    image_data = fits.getdata(image_file, ext=0)







The data is now stored as a 2D numpy array. Print the dimensions using the
shape attribute:



.. code-block:: python


    print(image_data.shape)





.. rst-class:: sphx-glr-script-out

 Out:

 .. code-block:: none

    (893, 891)


Display the image data:



.. code-block:: python


    plt.figure()
    plt.imshow(image_data, cmap='gray')
    plt.colorbar()



.. image:: /generated/examples/io/images/sphx_glr_plot_fits-image_001.png
    :class: sphx-glr-single-img




**Total running time of the script:** ( 0 minutes  0.742 seconds)


.. _sphx_glr_download_generated_examples_io_plot_fits-image.py:


.. only :: html

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



  .. container:: sphx-glr-download

     :download:`Download Python source code: plot_fits-image.py <plot_fits-image.py>`



  .. container:: sphx-glr-download

     :download:`Download Jupyter notebook: plot_fits-image.ipynb <plot_fits-image.ipynb>`


.. only:: html

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

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