CODEWITHSUNDEEP
pythonimagecomputer-visionscikit-image
information_interchange
information_interchange

Reputation: 3128

Skimage imread returns img_arrayndarray; what are the properties?

Really surprised but I cannot find any documentation on img_arrayndarray which is what skimage's imread returns.

https://scikit-image.org/docs/dev/api/skimage.io.html#skimage.io.imread

My primary question is what properties/methods etc. this object has.

Alternatively, is there a reason the documentation is so lacking? For example is it common practice to just turn the imread into a numpy array? Thanks

Upvotes: 0

Views: 1375

Answers (2)

soupault
soupault

Reputation: 6510

A bit more details to Stefan's answer:

scikit-image doesn't internally implements IO capabilities, but rather wraps and delegates them to external libraries (referred to as "plugings").

One can see the supported plugins here - https://scikit-image.org/docs/dev/api/skimage.io.html, and the plugins available for his or her own environment by making a call to skimage.io.find_available_plugins. The plugins are loaded following a specific priority list.

The issue you are seeing is related to the error in dtype validation in one of the plugins. Recently, a similar bug has been fixed for imageio plugin (https://github.com/scikit-image/scikit-image/pull/3837) and it will be incorporated into 0.14.3 (LTS), 0.15.1/0.16 (latest) releases.

Upvotes: 1

warped
warped

Reputation: 9481

Testing the function,
using Python 2.7.13, Ipython 5.1.0, skimage 0.13.0,
and Python 3.6.7, Ipython 7.4.0, skimage 0.15.0:

 In [1]: from skimage import io

 In [2]: a = io.imread('testimg.tif')

 In [3]: type(a)  
 Out[3]: numpy.ndarray

your link to the documentation is skimage 0.16.0, but I think it is safe to assume that there simply is a typo in the documentation.

edit: also, looking at the source:

def imread(fname, as_gray=False, plugin=None, flatten=None,
           **plugin_args):
    """Load an image from file.
    Parameters
    ----------
    fname : string
        Image file name, e.g. ``test.jpg`` or URL.
    as_gray : bool, optional
        If True, convert color images to gray-scale (64-bit floats).
        Images that are already in gray-scale format are not converted.
    plugin : str, optional
        Name of plugin to use.  By default, the different plugins are
        tried (starting with imageio) until a suitable
        candidate is found.  If not given and fname is a tiff file, the
        tifffile plugin will be used.
    Other Parameters
    ----------------
    plugin_args : keywords
        Passed to the given plugin.
    flatten : bool
        Backward compatible keyword, superseded by `as_gray`.
    Returns
    -------
    img_array : ndarray
        The different color bands/channels are stored in the
        third dimension, such that a gray-image is MxN, an
        RGB-image MxNx3 and an RGBA-image MxNx4.

Upvotes: 2

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