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Fix imread issues mentioned on matplotlib-devel #616

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Fix imread issues mentioned on matplotlib-devel #616

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9a9813f
Don't flip PIL image
cgohlke Dec 9, 2011
b1a0a1a
Fix conversion of PIL 16 bit grayscale images to 8 bit
cgohlke Dec 9, 2011
98d706b
Add detection of file extension for file-like objects
cgohlke Dec 9, 2011
8408cb3
Allow pil_to_array to return arrays with dtypes other than uint8
cgohlke Dec 10, 2011
e87bc08
No more need to flip PIL images in imshow
cgohlke Dec 10, 2011
463a3b5
Return native byte order uint16
cgohlke Dec 10, 2011
de5ed7c
Test reading uint16 grayscale image with PIL
cgohlke Dec 10, 2011
64d3264
Add uint16 image
cgohlke Dec 12, 2011
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2 changes: 1 addition & 1 deletion examples/pylab_examples/image_demo3.py
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,7 @@
figure(figsize=figsize)
ax = axes([0,0,1,1], frameon=False)
ax.set_axis_off()
im = imshow(lena, origin='lower')
im = imshow(lena)

show()

24 changes: 18 additions & 6 deletions lib/matplotlib/image.py
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@
"""
from __future__ import division
import os, warnings
import math

import numpy as np
from numpy import ma
Expand Down Expand Up @@ -1189,6 +1190,9 @@ def pilread():
if cbook.is_string_like(fname):
basename, ext = os.path.splitext(fname)
ext = ext.lower()[1:]
elif hasattr(fname, 'name'):
basename, ext = os.path.splitext(fname.name)
ext = ext.lower()[1:]
else:
ext = 'png'
else:
Expand Down Expand Up @@ -1255,14 +1259,14 @@ def imsave(fname, arr, vmin=None, vmax=None, cmap=None, format=None,

def pil_to_array( pilImage ):
"""
load a PIL image and return it as a numpy array of uint8. For
load a PIL image and return it as a numpy array. For
grayscale images, the return array is MxN. For RGB images, the
return value is MxNx3. For RGBA images the return value is MxNx4
"""
def toarray(im):
'return a 1D array of floats'
x_str = im.tostring('raw',im.mode,0,-1)
x = np.fromstring(x_str,np.uint8)
def toarray(im, dtype=np.uint8):
'return a 1D array of dtype'
x_str = im.tostring('raw', im.mode)
x = np.fromstring(x_str, dtype)
return x

if pilImage.mode in ('RGBA', 'RGBX'):
Expand All @@ -1279,7 +1283,15 @@ def toarray(im):
x = toarray(im)
x.shape = im.size[1], im.size[0], 3
return x

elif pilImage.mode.startswith('I;16'):
# return MxN luminance array of uint16
im = pilImage
if im.mode.endswith('B'):
x = toarray(im, '>u2')
else:
x = toarray(im, '<u2')
x.shape = im.size[1], im.size[0]
return x.astype('=u2')
else: # try to convert to an rgba image
try:
im = pilImage.convert('RGBA')
Expand Down
Binary file added lib/matplotlib/tests/baseline_images/test_image/uint16.tif
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5 changes: 5 additions & 0 deletions lib/matplotlib/tests/test_image.py
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Original file line number Diff line number Diff line change
Expand Up @@ -75,6 +75,11 @@ def test_image_python_io():
buffer.seek(0)
plt.imread(buffer)

def test_imread_pil_uint16():
img = plt.imread(os.path.join(os.path.dirname(__file__),
'baseline_images/test_image/uint16.tif'))
assert (img.dtype == np.uint16)

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Could this be turned into an image comparison test to ensure that the fields of the image are correctly read in, endianness works etc. Or if that's not practical, maybe assert about a few of the data values?

# def test_image_unicode_io():
# fig = plt.figure()
# ax = fig.add_subplot(111)
Expand Down