[Pkg-mozext-commits] [adblock-plus] 12/41: Issue 2038 - Convert palette images with transparency to RGBA before pasting
David Prévot
taffit at moszumanska.debian.org
Wed Mar 18 18:21:37 UTC 2015
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taffit pushed a commit to branch master
in repository adblock-plus.
commit 1a7ebdbf27ec4de2530f12506e70d4ffb2631917
Author: Sebastian Noack <sebastian at adblockplus.org>
Date: Tue Feb 24 16:53:35 2015 +0100
Issue 2038 - Convert palette images with transparency to RGBA before pasting
---
imageConversion.py | 36 +++++++++++++++++++++---------------
1 file changed, 21 insertions(+), 15 deletions(-)
diff --git a/imageConversion.py b/imageConversion.py
index 021a762..bbdcfc5 100644
--- a/imageConversion.py
+++ b/imageConversion.py
@@ -16,20 +16,6 @@ except ImportError:
from imageCompression import image_to_file
-def get_alpha(image):
- if image.mode in ('RGBA', 'LA'):
- return image.split()[image.getbands().index('A')]
-
- # In order to generate an alpha channel for images using a palette, we
- # convert the image to RGBA. It's important to use RGBA, not LA (grayscale+alpha),
- # since PIL can't reliably convert P to LA. Also initially, we created an
- # alpha channel by replacing opaque pixels with a high mark and transparent
- # pixels with a low mark. However, it turned out that you can't rely on the
- # value of Image.info['transparency'] since in some cases it might be an
- # unparsed string instead an int indicating the value of transparent pixels.
- if image.mode == 'P' and 'transparency' in image.info:
- return image.convert('RGBA').split()[3]
-
def load_image(path):
image = Image.open(path)
# Make sure the image is loaded, some versions of PIL load images lazily.
@@ -65,8 +51,28 @@ def ensure_same_mode(im1, im2):
)
def filter_contrastToAlpha(image, baseDir):
+ # In order to generate an alpha channel for images using a palette, we must
+ # convert the image to RGBA. It's important to use RGBA, not LA (grayscale+alpha),
+ # since PIL can't reliably convert P to LA. Also initially, we created an
+ # alpha channel by replacing opaque pixels with a high mark and transparent
+ # pixels with a low mark. However, it turned out that you can't rely on the
+ # value of Image.info['transparency'] since in case the transparency is
+ # specified in bytes (pngout loves to do that), we can't associate that value
+ # with transparent pixels. Moreover, some versions of PIL raise a warning
+ # when such images are pasted into another image.
+ if image.mode == 'P' and 'transparency' in image.info:
+ image = image.convert('RGBA')
+
+ # Image.paste() ignores the alpha channel of the pasted image, but expects
+ # the mask to be passed as separate argument. So we have to extract the alpha
+ # channel (if any) from the image we are going to paste.
+ if image.mode in ('RGBA', 'LA'):
+ mask = image.split()[image.getbands().index('A')]
+ else:
+ mask = None
+
alpha = Image.new('L', image.size, 255)
- alpha.paste(image, mask=get_alpha(image))
+ alpha.paste(image, mask=mask)
alpha = ImageOps.invert(alpha)
alpha = ImageOps.autocontrast(alpha)
--
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