.. _sphx_glr_auto_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 dispay 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 download_file
    from astropy.io import fits

    image_file = download_file('http://data.astropy.org/tutorials/FITS-images/HorseHead.fits',
                               cache=True)





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

 Out::

      Downloading http://data.astropy.org/tutorials/FITS-images/HorseHead.fits [Done]


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::

      Filename: /home/docs/.astropy/cache/download/py2/2c9202ae878ecfcb60878ceb63837f5f
    No.    Name         Type      Cards   Dimensions   Format
    0    PRIMARY     PrimaryHDU     161   (891, 893)   int16   
    1    er.mask     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::

      (893, 891)


Display the image data:


.. code-block:: python


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



.. image:: /auto_examples/io/images/sphx_glr_plot_fits-image_001.png
    :align: center




**Total running time of the script:**
(0 minutes 0.397 seconds)



.. container:: sphx-glr-download

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


.. container:: sphx-glr-download

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