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https://github.com/wassname/scikit-image.git
synced 2026-07-17 11:32:45 +08:00
ENH: Refactor ImageCollection to allow more general file loading schemes.
This commit is contained in:
Stefan van der Walt
@@ -150,7 +150,7 @@ class MultiImage(object):
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return self._numframes
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def __str__(self):
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return str(self.filename) + ' [%s frames]'%self._numframes
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return str(self.filename) + ' [%s frames]' % self._numframes
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class ImageCollection(object):
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@@ -160,27 +160,56 @@ class ImageCollection(object):
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Parameters
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----------
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file_pattern : str or list of str
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Path(s) and pattern(s) of files to load. The path can be absolute
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or relative. If given as a list of strings, each string in the list
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is a separate pattern. Files are found by passing the pattern(s) to
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the ``glob.glob`` function.
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load_pattern : str or list
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Pattern glob or filenames to load. The path can be absolute or
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relative. Multiple patterns should be separated by a colon,
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e.g. '/tmp/work/*.png:/tmp/other/*.jpg'. Also see
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implementation notes below.
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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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as_grey : bool, optional
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If True, convert the input images to grey-scale. This does not
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affect images that are already in a grey-scale format.
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dtype : dtype, optional
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NumPy data-type specifier. If given, the returned image has this type.
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If None (default), the data-type is determined automatically.
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Other parameters
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----------------
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load_func : callable
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``imread`` by default. See notes below.
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Attributes
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----------
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files : list of str
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A list of files in the collection, ordered alphabetically.
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as_grey : bool
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Whether images are converted to grey-scale.
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If a glob string is given for `load_pattern`, this attribute
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stores the expanded file list. Otherwise, this is simply
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equal to `load_pattern`.
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Notes
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-----
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ImageCollection can be modified to load images from an arbitrary
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source by specifying a combination of `load_pattern` and
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`load_func`. For an ImageCollection ``ic``, ``ic[5]`` uses
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``load_func(file_pattern[5])`` to load the image.
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Imagine, for example, an ImageCollection that loads every tenth
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frame from a video file::
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class AVILoader:
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video_file = 'myvideo.avi'
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def __call__(self, frame):
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return video_read(self.video_file, frame)
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avi_load = AVILoader()
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frames = range(0, 1000, 10) # 0, 10, 20, ...
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ic = ImageCollection(frames, load_func=avi_load)
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x = ic[5] # calls avi_load(frames[5]) or equivalently avi_load(50)
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Another use of ``load_func`` would be to convert all images to ``uint8``::
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def imread_convert(f):
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return imread(f).astype(np.uint8)
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ic = ImageCollection('/tmp/*.png', load_func=imread_convert)
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Examples
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--------
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@@ -193,23 +222,19 @@ class ImageCollection(object):
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>>> coll[0].shape
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(128, 128, 3)
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When `as_grey` is set to True, a color image is returned in grey-scale:
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>>> coll = io.ImageCollection(data_dir + '/lena*.png', as_grey=True)
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>>> coll[0].shape
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(128, 128)
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>>> ic = io.ImageCollection('/tmp/work/*.png:/tmp/other/*.jpg')
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"""
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def __init__(self, file_pattern, conserve_memory=True, as_grey=False,
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dtype=None):
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def __init__(self, load_pattern, conserve_memory=True, load_func=None):
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"""Load and manage a collection of images."""
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if isinstance(file_pattern, basestring):
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self._files = sorted(glob(file_pattern))
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elif isinstance(file_pattern, list):
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if isinstance(load_pattern, basestring):
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load_pattern = load_pattern.split(':')
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self._files = []
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for pattern in file_pattern:
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for pattern in load_pattern:
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self._files.extend(glob(pattern))
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self._files.sort()
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else:
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self._files = load_pattern
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if conserve_memory:
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memory_slots = 1
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@@ -218,27 +243,18 @@ class ImageCollection(object):
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self._conserve_memory = conserve_memory
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self._cached = None
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self._as_grey = as_grey
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self._dtype = dtype
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if load_func is None:
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self.load_func = imread
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else:
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self.load_func = load_func
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self.data = np.empty(memory_slots, dtype=object)
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@property
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def files(self):
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return self._files
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def _get_as_grey(self):
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"""Whether images are converted to grey-scale.
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If this property is changed, all images in memory get reloaded.
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"""
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return self._as_grey
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def _set_as_grey(self, newgrey):
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if not newgrey == self._as_grey:
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self._as_grey = newgrey
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self.reload()
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as_grey = property(_get_as_grey, _set_as_grey)
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@property
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def conserve_memory(self):
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return self._conserve_memory
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@@ -263,8 +279,7 @@ class ImageCollection(object):
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if (self.conserve_memory and n != self._cached) or \
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(self.data[idx] is None):
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self.data[idx] = imread(self.files[n], self.as_grey,
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dtype=self._dtype)
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self.data[idx] = self.load_func(self.files[n])
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self._cached = n
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return self.data[idx]
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@@ -291,31 +306,13 @@ class ImageCollection(object):
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return str(self.files)
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def reload(self, n=None):
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"""Reload one or more images from file.
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"""Clear the image cache.
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Parameters
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----------
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n : None or int
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The number of the image to reload. If None (default), all images in
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memory are reloaded. If `n` specifies an image not yet in memory,
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it is loaded.
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Clear the cache for this image only. By default, the
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entire cache is erased.
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Returns
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-------
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None
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Notes
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-----
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`reload` is used to reload all images in memory when `as_grey` is
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changed.
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"""
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if n is not None:
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n = self._check_numimg(n)
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idx = n % len(self.data)
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self.data[idx] = imread(self.files[n], self.as_grey,
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dtype=self._dtype)
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else:
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for idx, img in enumerate(self.data):
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if img is not None:
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self.data[idx] = imread(self.files[idx], self.as_grey,
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dtype=self._dtype)
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self.data = np.empty_like(self.data)
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@@ -37,11 +37,13 @@ class TestImageCollection():
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self.collection.files = f
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assert_raises(AttributeError, set_files, 'newfiles')
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def test_as_grey_property(self):
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self.collection.as_grey = False
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assert self.collection[1].ndim == 3
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self.collection.as_grey = True
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assert self.collection[1].ndim == 2
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def test_custom_load(self):
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load_pattern = [(1, 'one'), (2, 'two')]
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def load_fn(x):
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return x
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ic = ImageCollection(load_pattern, load_func=load_fn)
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assert_equal(ic[1], (2, 'two'))
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class TestMultiImage():
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