202 lines
6.2 KiB
Python
202 lines
6.2 KiB
Python
import numpy as np
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from ..io.manage_plugins import call_plugin
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from ..color.colorconv import rgb2gray, rgba2rgb
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from .util import file_or_url_context
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from ..exposure import is_low_contrast
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from .._shared.utils import warn
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__all__ = ['imread', 'imsave', 'imshow', 'show',
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'imread_collection', 'imshow_collection']
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def imread(fname, as_gray=False, plugin=None, **plugin_args):
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"""Load an image from file.
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Parameters
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----------
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fname : string
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Image file name, e.g. ``test.jpg`` or URL.
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as_gray : bool, optional
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If True, convert color images to gray-scale (64-bit floats).
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Images that are already in gray-scale format are not converted.
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plugin : str, optional
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Name of plugin to use. By default, the different plugins are
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tried (starting with imageio) until a suitable
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candidate is found. If not given and fname is a tiff file, the
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tifffile plugin will be used.
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Other Parameters
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----------------
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plugin_args : keywords
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Passed to the given plugin.
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Returns
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-------
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img_array : ndarray
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The different color bands/channels are stored in the
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third dimension, such that a gray-image is MxN, an
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RGB-image MxNx3 and an RGBA-image MxNx4.
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"""
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if plugin is None and hasattr(fname, 'lower'):
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if fname.lower().endswith(('.tiff', '.tif')):
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plugin = 'tifffile'
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with file_or_url_context(fname) as fname:
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img = call_plugin('imread', fname, plugin=plugin, **plugin_args)
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if not hasattr(img, 'ndim'):
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return img
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if img.ndim > 2:
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if img.shape[-1] not in (3, 4) and img.shape[-3] in (3, 4):
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img = np.swapaxes(img, -1, -3)
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img = np.swapaxes(img, -2, -3)
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if as_gray:
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if img.shape[2] == 4:
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img = rgba2rgb(img)
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img = rgb2gray(img)
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return img
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def imread_collection(load_pattern, conserve_memory=True,
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plugin=None, **plugin_args):
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"""
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Load a collection of images.
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Parameters
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----------
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load_pattern : str or list
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List of objects to load. These are usually filenames, but may
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vary depending on the currently active plugin. See the docstring
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for ``ImageCollection`` for the default behaviour of this parameter.
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conserve_memory : bool, optional
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If True, never keep more than one in memory at a specific
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time. Otherwise, images will be cached once they are loaded.
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Returns
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-------
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ic : ImageCollection
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Collection of images.
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Other Parameters
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----------------
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plugin_args : keywords
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Passed to the given plugin.
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"""
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return call_plugin('imread_collection', load_pattern, conserve_memory,
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plugin=plugin, **plugin_args)
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def imsave(fname, arr, plugin=None, check_contrast=True, **plugin_args):
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"""Save an image to file.
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Parameters
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----------
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fname : str
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Target filename.
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arr : ndarray of shape (M,N) or (M,N,3) or (M,N,4)
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Image data.
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plugin : str, optional
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Name of plugin to use. By default, the different plugins are
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tried (starting with imageio) until a suitable
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candidate is found. If not given and fname is a tiff file, the
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tifffile plugin will be used.
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check_contrast : bool, optional
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Check for low contrast and print warning (default: True).
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Other Parameters
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----------------
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plugin_args : keywords
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Passed to the given plugin.
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Notes
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-----
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When saving a JPEG, the compression ratio may be controlled using the
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``quality`` keyword argument which is an integer with values in [1, 100]
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where 1 is worst quality and smallest file size, and 100 is best quality
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and largest file size (default 75). This is only available when using
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the PIL and imageio plugins.
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"""
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if plugin is None and hasattr(fname, 'lower'):
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if fname.lower().endswith(('.tiff', '.tif')):
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plugin = 'tifffile'
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if arr.dtype == bool:
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warn('%s is a boolean image: setting True to 255 and False to 0. '
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'To silence this warning, please convert the image using '
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'img_as_ubyte.' % fname, stacklevel=2)
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arr = arr.astype('uint8') * 255
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if check_contrast and is_low_contrast(arr):
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warn('%s is a low contrast image' % fname)
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return call_plugin('imsave', fname, arr, plugin=plugin, **plugin_args)
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def imshow(arr, plugin=None, **plugin_args):
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"""Display an image.
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Parameters
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----------
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arr : ndarray or str
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Image data or name of image file.
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plugin : str
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Name of plugin to use. By default, the different plugins are
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tried (starting with imageio) until a suitable
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candidate is found.
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Other Parameters
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----------------
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plugin_args : keywords
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Passed to the given plugin.
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"""
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if isinstance(arr, str):
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arr = call_plugin('imread', arr, plugin=plugin)
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return call_plugin('imshow', arr, plugin=plugin, **plugin_args)
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def imshow_collection(ic, plugin=None, **plugin_args):
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"""Display a collection of images.
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Parameters
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----------
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ic : ImageCollection
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Collection to display.
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plugin : str
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Name of plugin to use. By default, the different plugins are
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tried until a suitable candidate is found.
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Other Parameters
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----------------
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plugin_args : keywords
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Passed to the given plugin.
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"""
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return call_plugin('imshow_collection', ic, plugin=plugin, **plugin_args)
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def show():
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'''Display pending images.
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Launch the event loop of the current gui plugin, and display all
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pending images, queued via `imshow`. This is required when using
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`imshow` from non-interactive scripts.
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A call to `show` will block execution of code until all windows
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have been closed.
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Examples
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--------
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>>> import skimage.io as io
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>>> for i in range(4):
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... ax_im = io.imshow(np.random.rand(50, 50))
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>>> io.show() # doctest: +SKIP
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'''
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return call_plugin('_app_show')
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