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Convert 8-bit PNG & GIF alpha channels to /SMasks in PDF #106

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josch merged 7 commits from tzahola/img2pdf:png-alpha-to-smask into main 2021-08-22 08:08:26 +00:00
Conversation 21 Commits 7 Files changed 2 +19 -5
1 changed files with 19 additions and 5 deletions
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src/img2pdf.py
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@ -760,7 +760,10 @@ class pdfdoc(object):
artborder=None,
iccp=None,
):
assert (color != Colorspace.RGBA and color != Colorspace.LA) or (imgformat == ImageFormat.PNG and smaskdata is not None)
assert (
(color != Colorspace.RGBA and color != Colorspace.LA)
or (imgformat == ImageFormat.PNG and smaskdata is not None)
)
if self.engine == Engine.pikepdf:
PdfArray = pikepdf.Array
@ -1222,7 +1225,7 @@ def get_imgmetadata(
):
# Must check the IHDR chunk for the bit depth, because PIL would lossily
# convert 16-bit RGBA/LA images to 8-bit.
if imgformat == ImageFormat.PNG and rawdata != None:
if imgformat == ImageFormat.PNG and rawdata is not None:
depth = rawdata[24]
if depth > 8:
logger.warning("Image with transparency and a bit depth of %d." % depth)
@ -1553,7 +1556,11 @@ def read_images(rawdata, colorspace, first_frame_only=False, rot=None):
color, ndpi, imgwidthpx, imgheightpx, rotation, iccp = get_imgmetadata(
imgdata, imgformat, default_dpi, colorspace, rawdata, rot
)
if color != Colorspace.RGBA and color != Colorspace.LA and "transparency" not in imgdata.info:
if (
color != Colorspace.RGBA
and color != Colorspace.LA
and "transparency" not in imgdata.info
):
pngidat, palette = parse_png(rawdata)
# PIL does not provide the information about the original bits per
# sample. Thus, we retrieve that info manually by looking at byte 9 in
@ -1745,7 +1752,11 @@ def read_images(rawdata, colorspace, first_frame_only=False, rot=None):
)
)
else:
if color == Colorspace.RGBA or color == Colorspace.LA or "transparency" in newimg.info:
if (
color == Colorspace.RGBA
or color == Colorspace.LA
or "transparency" in newimg.info
):
if color == Colorspace.RGBA:
newcolor = color
r, g, b, a = newimg.split()
@ -1760,7 +1771,10 @@ def read_images(rawdata, colorspace, first_frame_only=False, rot=None):
newimg = Image.merge("RGB", (r, g, b))
smaskidat, _, _ = to_png_data(a)
logger.warning("Image contains an alpha channel which will be stored as a separate soft mask (/SMask) image in PDF.")
logger.warning(
"Image contains an alpha channel which will be stored "
"as a separate soft mask (/SMask) image in PDF."
)
else:
newcolor = color
smaskidat = None