mirror of
https://github.com/wassname/scikit-image.git
synced 2026-06-30 22:03:45 +08:00
Stefan van der Walt
55 lines
1.3 KiB
Python
55 lines
1.3 KiB
Python
__all__ = ['imread']
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import plugin
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import numpy as np
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try:
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from PIL import Image
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has_pil = True
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except ImportError:
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has_pil = False
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def imread(fname, as_grey=False, dtype=None):
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"""Load an image from file.
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"""
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im = Image.open(fname)
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if im.mode == 'P':
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if palette_is_grayscale(im):
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im = im.convert('L')
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else:
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im = im.convert('RGB')
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if as_grey and not \
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im.mode in ('1', 'L', 'I', 'F', 'I;16', 'I;16L', 'I;16B'):
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im = im.convert('F')
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return np.array(im, dtype=dtype)
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def palette_is_grayscale(pil_image):
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"""Return True if PIL image in palette mode is grayscale.
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Parameters
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----------
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pil_image : PIL image
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PIL Image that is in Palette mode.
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Returns
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-------
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is_grayscale : bool
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True if all colors in image palette are gray.
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"""
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assert pil_image.mode == 'P'
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# get palette as an array with R, G, B columns
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palette = np.asarray(pil_image.getpalette()).reshape((256, 3))
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# Not all palette colors are used; unused colors have junk values.
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start, stop = pil_image.getextrema()
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valid_palette = palette[start:stop]
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# Image is grayscale if channel differences (R - G and G - B)
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# are all zero.
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return np.allclose(np.diff(valid_palette), 0)
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if has_pil:
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plugin.register('pil', read=imread)
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