mirror of
https://github.com/wassname/scikit-image.git
synced 2026-07-05 20:16:04 +08:00
Stefan van der Walt
69 lines
2.0 KiB
Python
69 lines
2.0 KiB
Python
import numpy as np
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# utilities to make life easier for plugin writers.
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def prepare_for_display(npy_img):
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'''Convert a 2D or 3D numpy array of any dtype into a
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3D numpy array with dtype uint8. This array will
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be suitable for use in passing to gui toolkits for
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image display purposes.
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Parameters
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----------
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npy_img : ndarray, 2D or 3D
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The image to convert for display
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Returns
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-------
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out : ndarray, 3D dtype=np.uint8
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The converted image. This is guaranteed to be a contiguous array.
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Notes
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-----
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If the input image is floating point, it is assumed that the data
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is in the range of 0.0 - 1.0. No check is made to assert this
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condition. The image is then scaled to be in the range 0 - 255
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and then cast to np.uint8
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For all other dtypes, the array is simply cast to np.uint8
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If a 2D array is passed, the single channel is replicated
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to the 2nd and 3rd channels.
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If the array contains an alpha channel, this channel is
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ignored.
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'''
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if len(npy_img.shape) < 2:
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raise ValueError('Image must be 2D or 3D array')
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height = npy_img.shape[0]
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width = npy_img.shape[1]
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out = np.empty((height, width, 3), dtype=np.uint8)
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if len(npy_img.shape) == 2 or \
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(len(npy_img.shape) == 3 and npy_img.shape[2] == 1):
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if npy_img.dtype in [np.float32, np.float64]:
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out[:,:,0] = npy_img*255
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out[:,:,1] = out[:,:,0]
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out[:,:,2] = out[:,:,0]
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else:
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out[:,:,0] = npy_img
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out[:,:,1] = npy_img
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out[:,:,2] = npy_img
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elif len(npy_img.shape) == 3:
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if npy_img.shape[2] == 3 or npy_img.shape[2] == 4:
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if npy_img.dtype in [np.float32, np.float64]:
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out[:,:,:3] = (npy_img[:,:,:3])*255
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else:
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out[:,:,:3] = npy_img[:,:,:3]
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else:
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raise ValueError('Image must have 1, 3, or 4 channels')
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else:
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raise ValueError('Image must have 2 or 3 dimensions')
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return out |