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Issue 6406754824880128: Issue 2038 - Convert palette images with transparency to RGBA before pasting (Closed)
Patch Set: Addressed comments Created Feb. 24, 2015, 5:19 p.m.
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1 # coding: utf-8 1 # coding: utf-8
2 2
3 # This Source Code Form is subject to the terms of the Mozilla Public 3 # This Source Code Form is subject to the terms of the Mozilla Public
4 # License, v. 2.0. If a copy of the MPL was not distributed with this 4 # License, v. 2.0. If a copy of the MPL was not distributed with this
5 # file, You can obtain one at http://mozilla.org/MPL/2.0/. 5 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
6 6
7 import os 7 import os
8 import re 8 import re
9 9
10 try: 10 try:
11 from PIL import Image 11 from PIL import Image
12 from PIL import ImageOps 12 from PIL import ImageOps
13 except ImportError: 13 except ImportError:
14 import Image 14 import Image
15 import ImageOps 15 import ImageOps
16 16
17 from imageCompression import image_to_file 17 from imageCompression import image_to_file
18 18
19 def get_alpha(image):
20 if image.mode in ('RGBA', 'LA'):
21 return image.split()[image.getbands().index('A')]
22
23 # In order to generate an alpha channel for images using a palette, we
24 # convert the image to RGBA. It's important to use RGBA, not LA (grayscale+alp ha),
25 # since PIL can't reliably convert P to LA. Also initially, we created an
26 # alpha channel by replacing opaque pixels with a high mark and transparent
27 # pixels with a low mark. However, it turned out that you can't rely on the
28 # value of Image.info['transparency'] since in some cases it might be an
29 # unparsed string instead an int indicating the value of transparent pixels.
30 if image.mode == 'P' and 'transparency' in image.info:
31 return image.convert('RGBA').split()[3]
32
33 def load_image(path): 19 def load_image(path):
34 image = Image.open(path) 20 image = Image.open(path)
35 # Make sure the image is loaded, some versions of PIL load images lazily. 21 # Make sure the image is loaded, some versions of PIL load images lazily.
36 image.load() 22 image.load()
37 return image 23 return image
38 24
39 def ensure_same_mode(im1, im2): 25 def ensure_same_mode(im1, im2):
40 # if both images already have the same mode (and palette, in 26 # if both images already have the same mode (and palette, in
41 # case of mode P), don't convert anything. Images with mode P, 27 # case of mode P), don't convert anything. Images with mode P,
42 # and a different palette, are the only case where images 28 # and a different palette, are the only case where images
(...skipping 15 matching lines...) Expand all
58 44
59 if any(im.mode in ('RGBA', 'LA', 'P') for im in (im1, im2)): 45 if any(im.mode in ('RGBA', 'LA', 'P') for im in (im1, im2)):
60 mode += 'A' 46 mode += 'A'
61 47
62 return ( 48 return (
63 im1 if im1.mode == mode else im1.convert(mode), 49 im1 if im1.mode == mode else im1.convert(mode),
64 im2 if im2.mode == mode else im2.convert(mode), 50 im2 if im2.mode == mode else im2.convert(mode),
65 ) 51 )
66 52
67 def filter_contrastToAlpha(image, baseDir): 53 def filter_contrastToAlpha(image, baseDir):
54 # In order to generate an alpha channel for images using a palette, we must
55 # convert the image to RGBA. It's important to use RGBA, not LA (grayscale+alp ha),
56 # since PIL can't reliably convert P to LA. Also initially, we created an
57 # alpha channel by replacing opaque pixels with a high mark and transparent
58 # pixels with a low mark. However, it turned out that you can't rely on the
59 # value of Image.info['transparency'] since in case the transparency is
60 # specified in bytes (pngout loves to do that), we can't associate that value
61 # with transparent pixels. Moreover, some versions of PIL raise a warning
62 # when such images are pasted into another image.
63 if image.mode == 'P' and 'transparency' in image.info:
64 image = image.convert('RGBA')
65
66 # Image.paste() ignores the alpha channel of the pasted image, but expects
67 # the mask to be passed as separate argument. So we have to extract the alpha
68 # channel (if any) from the image we are going to paste.
69 if image.mode in ('RGBA', 'LA'):
70 mask = image.split()[image.getbands().index('A')]
71 else:
72 mask = None
73
68 alpha = Image.new('L', image.size, 255) 74 alpha = Image.new('L', image.size, 255)
69 alpha.paste(image, mask=get_alpha(image)) 75 alpha.paste(image, mask=mask)
70 alpha = ImageOps.invert(alpha) 76 alpha = ImageOps.invert(alpha)
71 alpha = ImageOps.autocontrast(alpha) 77 alpha = ImageOps.autocontrast(alpha)
72 78
73 return Image.merge('LA', [Image.new('L', image.size), alpha]) 79 return Image.merge('LA', [Image.new('L', image.size), alpha])
74 80
75 def filter_blend(image, baseDir, filename, opacity): 81 def filter_blend(image, baseDir, filename, opacity):
76 image, overlay = ensure_same_mode( 82 image, overlay = ensure_same_mode(
77 image, 83 image,
78 load_image(os.path.join( 84 load_image(os.path.join(
79 baseDir, 85 baseDir,
(...skipping 14 matching lines...) Expand all
94 for step in steps: 100 for step in steps:
95 filter, args = re.match(r'([^(]+)(?:\((.*)\))?', step).groups() 101 filter, args = re.match(r'([^(]+)(?:\((.*)\))?', step).groups()
96 args = re.split(r'\s*,\s*', args) if args else () 102 args = re.split(r'\s*,\s*', args) if args else ()
97 image = globals()['filter_' + filter](image, baseDir, *args) 103 image = globals()['filter_' + filter](image, baseDir, *args)
98 104
99 file = image_to_file(image, filename) 105 file = image_to_file(image, filename)
100 try: 106 try:
101 files[filename] = file.read() 107 files[filename] = file.read()
102 finally: 108 finally:
103 file.close() 109 file.close()
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