mirror of
https://github.com/wassname/scikit-image.git
synced 2026-06-28 03:19:12 +08:00
Juan Nunez-Iglesias
157 lines
4.6 KiB
Python
157 lines
4.6 KiB
Python
from collections import namedtuple
|
|
import numpy as np
|
|
import warnings
|
|
import matplotlib.pyplot as plt
|
|
from skimage.util import dtype as dtypes
|
|
|
|
|
|
_default_colormap = 'gray'
|
|
_nonstandard_colormap = 'cubehelix'
|
|
_diverging_colormap = 'RdBu'
|
|
|
|
|
|
ImageProperties = namedtuple('ImageProperties',
|
|
['signed', 'out_of_range_float',
|
|
'low_dynamic_range', 'unsupported_dtype'])
|
|
|
|
|
|
def _get_image_properties(image):
|
|
"""Determine nonstandard properties of an input image.
|
|
|
|
Parameters
|
|
----------
|
|
image : array
|
|
The input image.
|
|
|
|
Returns
|
|
-------
|
|
ip : ImageProperties named tuple
|
|
The properties of the image:
|
|
|
|
- signed: whether the image has negative values.
|
|
- out_of_range_float: if the image has floating point data
|
|
outside of [-1, 1].
|
|
- low_dynamic_range: if the image is in the standard image
|
|
range (e.g. [0, 1] for a floating point image) but its
|
|
dynamic range would be too small to display with standard
|
|
image ranges.
|
|
- unsupported_dtype: if the image data type is not a
|
|
standard skimage type, e.g. ``numpy.uint64``.
|
|
"""
|
|
immin, immax = np.min(image), np.max(image)
|
|
imtype = image.dtype.type
|
|
try:
|
|
lo, hi = dtypes.dtype_range[imtype]
|
|
except KeyError:
|
|
lo, hi = immin, immax
|
|
|
|
signed = immin < 0
|
|
out_of_range_float = (np.issubdtype(image.dtype, np.float) and
|
|
(immin < lo or immax > hi))
|
|
low_dynamic_range = (immin != immax and
|
|
(float(immax - immin) / (hi - lo)) < (1. / 255))
|
|
unsupported_dtype = image.dtype not in dtypes._supported_types
|
|
|
|
ip = ImageProperties(signed, out_of_range_float,
|
|
low_dynamic_range, unsupported_dtype)
|
|
return ip
|
|
|
|
|
|
def _raise_warnings(image_properties):
|
|
"""Raise the appropriate warning for each nonstandard image type.
|
|
|
|
Parameters
|
|
----------
|
|
image_properties : ImageProperties named tuple
|
|
The properties of the considered image.
|
|
"""
|
|
ip = image_properties
|
|
if ip.unsupported_dtype:
|
|
warnings.warn("Non-standard image type; displaying image with "
|
|
"stretched contrast.")
|
|
if ip.low_dynamic_range:
|
|
warnings.warn("Low image dynamic range; displaying image with "
|
|
"stretched contrast.")
|
|
if ip.out_of_range_float:
|
|
warnings.warn("Float image out of standard range; displaying image "
|
|
"with stretched contrast.")
|
|
|
|
|
|
def _get_display_range(image):
|
|
"""Return the display range for a given set of image properties.
|
|
|
|
Parameters
|
|
----------
|
|
image : array
|
|
The input image.
|
|
|
|
Returns
|
|
-------
|
|
lo, hi : same type as immin, immax
|
|
The display range to be used for the input image.
|
|
cmap : string
|
|
The name of the colormap to use.
|
|
"""
|
|
ip = _get_image_properties(image)
|
|
immin, immax = np.min(image), np.max(image)
|
|
if ip.signed:
|
|
magnitude = max(abs(immin), abs(immax))
|
|
lo, hi = -magnitude, magnitude
|
|
cmap = _diverging_colormap
|
|
elif any(ip):
|
|
_raise_warnings(ip)
|
|
lo, hi = immin, immax
|
|
cmap = _nonstandard_colormap
|
|
else:
|
|
lo = 0
|
|
imtype = image.dtype.type
|
|
hi = dtypes.dtype_range[imtype][1]
|
|
cmap = _default_colormap
|
|
return lo, hi, cmap
|
|
|
|
|
|
def imshow(im, *args, **kwargs):
|
|
"""Show the input image and return the current axes.
|
|
|
|
Images are assumed to have standard range for their type. For
|
|
example, if a floating point image has values in [0, 0.5], the
|
|
most intense color will be gray50, not white, as would be the
|
|
default in matplotlib.
|
|
|
|
In contrast, if the image exceeds the standard range, this
|
|
function defaults back to displaying exactly the range of the
|
|
input image, along with a colorbar to clearly indicate that
|
|
this range transformation has occurred.
|
|
|
|
Parameters
|
|
----------
|
|
im : array, shape (M, N[, 3])
|
|
The image to display.
|
|
|
|
*args, **kwargs : positional and keyword arguments
|
|
These are passed directly to `matplotlib.pyplot.imshow`.
|
|
|
|
Returns
|
|
-------
|
|
ax_im : `matplotlib.pyplot.AxesImage`
|
|
The `AxesImage` object returned by `plt.imshow`.
|
|
"""
|
|
if plt.gca().has_data():
|
|
plt.figure()
|
|
lo, hi, cmap = _get_display_range(im)
|
|
kwargs.setdefault('interpolation', 'nearest')
|
|
kwargs.setdefault('cmap', cmap)
|
|
kwargs.setdefault('vmin', lo)
|
|
kwargs.setdefault('vmax', hi)
|
|
ax_im = plt.imshow(im, *args, **kwargs)
|
|
if cmap != _default_colormap:
|
|
plt.colorbar()
|
|
return ax_im
|
|
|
|
imread = plt.imread
|
|
show = plt.show
|
|
|
|
|
|
def _app_show():
|
|
show()
|