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Tutorial
========
Installation
~~~~~~~~~~~~
The package is available on PyPi. Install it using:
::
pip install nd2reader
If you don't already have the packages ``numpy``, ``pims``, ``six`` and
``xmltodict``, they will be installed automatically if you use the
``setup.py`` script. ``nd2reader`` is an order of magnitude faster in
Python 3. I recommend using it unless you have no other choice. Python
2.7 and Python >= 3.4 are supported.
Installation via Conda Forge
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Installing ``nd2reader`` from the ``conda-forge`` channel can be
achieved by adding ``conda-forge`` to your channels with:
::
conda config --add channels conda-forge
Once the ``conda-forge`` channel has been enabled, ``nd2reader`` can be
installed with:
::
conda install nd2reader
It is possible to list all of the versions of ``nd2reader`` available on
your platform with:
::
conda search nd2reader --channel conda-forge
Opening ND2s
~~~~~~~~~~~~
``nd2reader`` follows the `pims <https://github.com/soft-matter/pims>`__
framework. To open a file and show the first frame:
.. code:: python
from nd2reader import ND2Reader
import matplotlib.pyplot as plt
with ND2Reader('my_directory/example.nd2') as images:
plt.imshow(images[0])
After opening the file, all ``pims`` features are supported. Please
refer to the `pims
documentation <http://soft-matter.github.io/pims/>`__.
ND2 metadata
~~~~~~~~~~~~
The ND2 file contains various metadata, such as acquisition information,
regions of interest and custom user comments. Most of this metadata is
parsed and available in dictionary form. For example:
.. code:: python
from nd2reader import ND2Reader
with ND2Reader('my_directory/example.nd2') as images:
# width and height of the image
print('%d x %d px' % (images.metadata['width'], images.metadata['height']))
All metadata properties are:
- ``width``: the width of the image in pixels
- ``height``: the height of the image in pixels
- ``date``: the date the image was taken
- ``fields_of_view``: the fields of view in the image
- ``frames``: a list of all frame numbers
- ``z_levels``: the z levels in the image
- ``total_images_per_channel``: the number of images per color channel
- ``channels``: the color channels
- ``pixel_microns``: the amount of microns per pixel
- ``rois``: the regions of interest (ROIs) defined by the user
- ``experiment``: information about the nature and timings of the ND
experiment
Iterating over fields of view
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Using ``NDExperiments`` in the Nikon software, it is possible to acquire
images on different ``(x, y)`` positions. This is referred to as
different fields of view. Using this reader, the fields of view are on
the ``v`` axis. For example:
.. code:: python
from nd2reader import ND2Reader
with ND2Reader('my_directory/example.nd2') as images:
# width and height of the image
print(images.metadata)
will output
.. code:: python
{'channels': ['BF100xoil-1x-R', 'BF+RITC'],
'date': datetime.datetime(2017, 10, 30, 14, 35, 18),
'experiment': {'description': 'ND Acquisition',
'loops': [{'duration': 0,
'sampling_interval': 0.0,
'start': 0,
'stimulation': False}]},
'fields_of_view': [0, 1],
'frames': [0],
'height': 1895,
'num_frames': 1,
'pixel_microns': 0.09214285714285715,
'total_images_per_channel': 6,
'width': 2368,
'z_levels': [0, 1, 2]}
for our example file. As you can see from the metadata, it has two
fields of view. We can also look at the sizes of the axes:
.. code:: python
print(images.sizes)
.. code:: python
{'c': 2, 't': 1, 'v': 2, 'x': 2368, 'y': 1895, 'z': 3}
As you can see, the fields of view are listed on the ``v`` axis. It is
therefore possible to loop over them like this:
.. code:: python
images.iter_axes = 'v'
for fov in images:
print(fov) # Frame containing one field of view
For more information on axis bundling and iteration, refer to the `pims
documentation <http://soft-matter.github.io/pims/v0.4/multidimensional.html#axes-bundling>`__.