josch/img2pdf
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src/img2pdf.py: do not use PNG encoding for CMYK input

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Johannes 'josch' Schauer 2018-07-17 16:47:27 +02:00
parent 3142824bab
commit 47a1e0c81e
Signed by: josch
GPG key ID: F2CBA5C78FBD83E1
1 changed files with 16 additions and 9 deletions
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25
src/img2pdf.py
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@ -830,15 +830,22 @@ def read_images(rawdata, colorspace, first_frame_only=False):
newimg = imgdata
else:
raise ValueError("unknown or unsupported colorspace: %s" % color.name)
# cheapo version to retrieve a PNG encoding of the payload is to
# just save it with PIL. In the future this could be replaced by
# dedicated function applying the Paeth PNG filter to the raw pixel
pngbuffer = BytesIO()
newimg.save(pngbuffer, format="png")
pngidat, palette = parse_png(pngbuffer.getvalue())
imgformat = ImageFormat.PNG
result.append((color, ndpi, imgformat, pngidat, imgwidthpx,
imgheightpx, palette))
# the PNG format does not support CMYK, so we fall back to normal
# compression
if color in [Colorspace.CMYK, Colorspace["CMYK;I"]]:
imggz = zlib.compress(newimg.tobytes())
result.append((color, ndpi, imgformat, imggz, imgwidthpx,
imgheightpx, []))
else:
# cheapo version to retrieve a PNG encoding of the payload is to
# just save it with PIL. In the future this could be replaced by
# dedicated function applying the Paeth PNG filter to the raw pixel
pngbuffer = BytesIO()
newimg.save(pngbuffer, format="png")
pngidat, palette = parse_png(pngbuffer.getvalue())
imgformat = ImageFormat.PNG
result.append((color, ndpi, imgformat, pngidat, imgwidthpx,
imgheightpx, palette))
img_page_count += 1
# the python-pil version 2.3.0-1ubuntu3 in Ubuntu does not have the
# close() method