mirror of
https://github.com/wassname/scikit-image.git
synced 2026-06-28 11:05:38 +08:00
Juan Nunez-Iglesias
84 lines
2.8 KiB
Python
84 lines
2.8 KiB
Python
import numpy as np
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import warnings
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import matplotlib.pyplot as plt
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from skimage.util import dtype as dtypes
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_default_colormap = 'gray'
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_nonstandard_colormap = 'cubehelix'
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_diverging_colormap = 'RdBu'
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def imshow(im, *args, **kwargs):
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"""Show the input image and return the current axes.
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Images are assumed to have standard range for their type. For
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example, if a floating point image has values in [0, 0.5], the
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most intense color will be gray50, not white, as would be the
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default in matplotlib.
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In contrast, if the image exceeds the standard range, this
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function defaults back to displaying exactly the range of the
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input image, along with a colorbar to clearly indicate that
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this range transformation has occurred.
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Parameters
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----------
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im : array, shape (M, N[, 3])
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The image to display.
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*args, **kwargs : positional and keyword arguments
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These are passed directly to `matplotlib.pyplot.imshow`.
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Returns
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-------
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ax_im : `matplotlib.pyplot.AxesImage`
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The `AxesImage` object returned by `plt.imshow`.
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"""
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if plt.gca().has_data():
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plt.figure()
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immin, immax = np.min(im), np.max(im)
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lo, hi = immin, immax
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cmap = _default_colormap
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supported_dtype = im.dtype in dtypes._supported_types
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if supported_dtype:
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lo, hi = dtypes.dtype_range[im.dtype.type]
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# for nonnegative float images, ensure lower bound is 0, not -1
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if immin > 0:
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lo = 0
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# for signed images, show diverging colormap centered at 0
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else:
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cmap = _diverging_colormap
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magnitude = max(-immin, abs(immax))
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lo, hi = -magnitude, magnitude
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else:
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warnings.warn("Non-standard image type; displaying image with "
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"stretched contrast.")
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out_of_range_float = (np.issubdtype(im.dtype, np.float) and
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(immin < lo or immax > hi))
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if out_of_range_float:
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warnings.warn("Float image out of standard range; displaying image "
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"with stretched contrast.")
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low_dynamic_range = (immin != immax and
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(float(immax - immin) / (hi - lo)) < (1. / 255))
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if low_dynamic_range:
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warnings.warn("Low image dynamic range; displaying image with "
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"stretched contrast.")
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if not supported_dtype or out_of_range_float or low_dynamic_range:
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cmap = _nonstandard_colormap
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kwargs.setdefault('interpolation', 'nearest')
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kwargs.setdefault('cmap', cmap)
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kwargs.setdefault('vmin', lo)
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kwargs.setdefault('vmax', hi)
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ax_im = plt.imshow(im, *args, **kwargs)
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if not supported_dtype or out_of_range_float or low_dynamic_range:
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plt.colorbar()
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return ax_im
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imread = plt.imread
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show = plt.show
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def _app_show():
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show()
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