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Imsave alpha #1224

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Merged
merged 2 commits into from
Sep 13, 2012
Merged

Imsave alpha #1224

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70358ac
Allow imsave() to handle RGB(A) input arrays
WeatherGod Sep 9, 2012
22c4a19
Added a test for imsave
WeatherGod Sep 9, 2012
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4 changes: 2 additions & 2 deletions lib/matplotlib/image.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1243,7 +1243,7 @@ def imsave(fname, arr, vmin=None, vmax=None, cmap=None, format=None,
If *format* is *None* and *fname* is a string, the output
format is deduced from the extension of the filename.
*arr*:
A 2D array.
An MxN (luminance), MxNx3 (RGB) or MxNx4 (RGBA) array.
Keyword arguments:
*vmin*/*vmax*: [ None | scalar ]
*vmin* and *vmax* set the color scaling for the image by fixing the
Expand All @@ -1266,7 +1266,7 @@ def imsave(fname, arr, vmin=None, vmax=None, cmap=None, format=None,
from matplotlib.backends.backend_agg import FigureCanvasAgg as FigureCanvas
from matplotlib.figure import Figure

figsize = [x / float(dpi) for x in arr.shape[::-1]]
figsize = [x / float(dpi) for x in (arr.shape[1], arr.shape[0])]
fig = Figure(figsize=figsize, dpi=dpi, frameon=False)
canvas = FigureCanvas(fig)
im = fig.figimage(arr, cmap=cmap, vmin=vmin, vmax=vmax, origin=origin)
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20 changes: 20 additions & 0 deletions lib/matplotlib/tests/test_image.py
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Expand Up @@ -128,6 +128,26 @@ def test_imsave():

assert_array_equal(arr_dpi1, arr_dpi100)

def test_imsave_color_alpha():
# The goal is to test that imsave will accept arrays with ndim=3 where
# the third dimension is color and alpha without raising any exceptions
from numpy import random
random.seed(1)
data = random.rand(256, 128, 4)

buff = io.BytesIO()
plt.imsave(buff, data)

buff.seek(0)
arr_buf = plt.imread(buff)

assert arr_buf.shape == data.shape

# Unfortunately, the AGG process "flattens" the RGBA data
# into an equivalent RGB data with no transparency. So we
# Can't directly compare the arrays like we could in some
# other imsave tests.

@image_comparison(baseline_images=['image_clip'])
def test_image_clip():
from math import pi
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