Imageio usage examples
======================
Some of these examples use Visvis to visualize the image data,
but one can also use Matplotlib to show the images.
Imageio provides a range of :doc:`example images <standardimages>`,
which can be used by using a URI like ``'imageio:chelsea.png'``. The images
are automatically downloaded if not already present on your system.
Therefore most examples below should just work.
Read an image of a cat
----------------------
Probably the most important thing you ever need.
.. code-block:: python
import imageio
im = imageio.imread('imageio:chelsea.png')
print(im.shape)
Read from fancy sources
-----------------------
Imageio can read from filenames, file objects, http, zipfiles and bytes.
.. code-block:: python
import imageio
import visvis as vv
im = imageio.imread('http://upload.wikimedia.org/wikipedia/commons/d/de/Wikipedia_Logo_1.0.png')
vv.imshow(im)
Note: reading from HTTP and zipfiles works for many formats including png and jpeg, but may not work
for all formats (some plugins "seek" the file object, which HTTP/zip streams do not support).
In such a case one can download/extract the file first. For HTTP one can use something like
``imageio.imread(imageio.core.urlopen(url).read(), '.gif')``.
Iterate over frames in a movie
------------------------------
.. code-block:: python
import imageio
reader = imageio.get_reader('imageio:cockatoo.mp4')
for i, im in enumerate(reader):
print('Mean of frame %i is %1.1f' % (i, im.mean()))
Grab screenshot or image from the clipboard
-------------------------------------------
(Screenshots are supported on Windows and OS X, clipboard on Windows only.)
.. code-block:: python
import imageio
im_screen = imageio.imread('<screen>')
im_clipboard = imageio.imread('<clipboard>')
Grab frames from your webcam
----------------------------
Use the special ``<video0>`` uri to read frames from your webcam (via
the ffmpeg plugin). You can replace the zero with another index in case
you have multiple cameras attached.
.. code-block:: python
import imageio
import visvis as vv
reader = imageio.get_reader('<video0>')
t = vv.imshow(reader.get_next_data(), clim=(0, 255))
for im in reader:
vv.processEvents()
t.SetData(im)
Convert a movie
------------------------------
Here we take a movie and convert it to gray colors. Of course, you
can apply any kind of (image) processing to the image here ...
.. code-block:: python
import imageio
reader = imageio.get_reader('imageio:cockatoo.mp4')
fps = reader.get_meta_data()['fps']
writer = imageio.get_writer('~/cockatoo_gray.mp4', fps=fps)
for im in reader:
writer.append_data(im[:, :, 1])
writer.close()
Read medical data (DICOM)
-------------------------
.. code-block:: python
import imageio
dirname = 'path/to/dicom/files'
# Read as loose images
ims = imageio.mimread(dirname, 'DICOM')
# Read as volume
vol = imageio.volread(dirname, 'DICOM')
# Read multiple volumes (multiple DICOM series)
vols = imageio.mvolread(dirname, 'DICOM')
Volume data
-----------
.. code-block:: python
import imageio
import visvis as vv
vol = imageio.volread('imageio:stent.npz')
vv.volshow(vol)
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