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Properly handle transparency for animations #5415

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Properly handle transparency for animations #5415

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30c2a09
Add 'flatten' kwarg to backend_agg savefig for print_png and print_ra…
cbreeden Nov 6, 2015
b8175a1
Fix width/height locations, and forgot to add alpha layer to flatten_…
cbreeden Nov 6, 2015
2fa1889
Move flatten_rgba to image.py and implment flatten_rgba for jpeg files.
cbreeden Nov 6, 2015
e0f1fd8
Removed typo
cbreeden Nov 6, 2015
d5fbd89
Clarify comment
cbreeden Nov 6, 2015
a57be1f
Appease the PEP8 gods. Somewhat of a sacraficial lamb if you ask me.
cbreeden Nov 6, 2015
0193d55
Add tests for flatten kwarg
cbreeden Nov 7, 2015
b2c4560
Fix typo in tests
cbreeden Nov 7, 2015
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Appease the PEP8 gods. Somewhat of a sacraficial lamb if you ask me.
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@cbreeden
cbreeden committed Nov 25, 2015
commit a57be1ff208c7828c5351a49c1b2ca26f2bc0967
17 changes: 9 additions & 8 deletions lib/matplotlib/image.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1503,6 +1503,7 @@ def thumbnail(infile, thumbfile, scale=0.1, interpolation='bilinear',
fig.savefig(thumbfile, dpi=dpi)
return fig


def flatten_rgba(src, bg=None):
"""
Flatten an RGBA image *src* with a background color *bg*.
Expand All @@ -1517,7 +1518,7 @@ def flatten_rgba(src, bg=None):

bg : Tuple(int,int,int), optional
Background color to merge *src* with. If no bg color is provided
the color from the rcParam 'savefig.facecolor' will be use.
the color from the rcParam 'savefig.facecolor' will be used.

Returns
-------
Expand All @@ -1529,18 +1530,18 @@ def flatten_rgba(src, bg=None):
rcParams.get('savefig.facecolor', 'white'))
bg = tuple([int(x * 255.0) for x in bg])

# Numpy images have dtype=uint8 which will overflow
# Numpy images have dtype=uint8 which will overflow for these calculations
src = src.astype(np.uint16)

alpha = src[:,:,3]
src_rgb = src[:,:,:3]
alpha = src[:, :, 3]
src_rgb = src[:, :, :3]
w, h, _ = src.shape

dest = np.empty((w, h, 4))
dest[:,:,0] = (255 - alpha)*bg[0] + alpha*src_rgb[:,:,0]
dest[:,:,1] = (255 - alpha)*bg[1] + alpha*src_rgb[:,:,1]
dest[:,:,2] = (255 - alpha)*bg[2] + alpha*src_rgb[:,:,2]
dest[:, :, 0] = (255 - alpha)*bg[0] + alpha*src_rgb[:, :, 0]
dest[:, :, 1] = (255 - alpha)*bg[1] + alpha*src_rgb[:, :, 1]
dest[:, :, 2] = (255 - alpha)*bg[2] + alpha*src_rgb[:, :, 2]
dest = (dest/255).astype(np.uint8)
dest[:,:,3] = 255
dest[:, :, 3] = 255

return dest