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src/img2pdf.py: allow PNG input without dpi units but non-square dpi aspect ratio

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Closes: #181
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Johannes Schauer Marin Rodrigues 2023-11-25 07:58:17 +01:00
parent 7678435eb7
commit fb9537d8b7
Signed by: josch
GPG key ID: F2CBA5C78FBD83E1
1 changed files with 13 additions and 1 deletions
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14
src/img2pdf.py
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@ -1311,7 +1311,19 @@ def get_imgmetadata(
else:
imgwidthpx, imgheightpx = imgdata.size
ndpi = imgdata.info.get("dpi", (default_dpi, default_dpi))
ndpi = imgdata.info.get("dpi")
if ndpi is None:
# the PNG plugin of PIL adds the undocumented "aspect" field instead of
# the "dpi" field if the PNG pHYs chunk unit is not set to meters
if imgformat == ImageFormat.PNG and imgdata.info.get("aspect") is not None:
aspect = imgdata.info["aspect"]
# make sure not to go below the default dpi
if aspect[0] > aspect[1]:
ndpi = (default_dpi * aspect[0] / aspect[1], default_dpi)
else:
ndpi = (default_dpi, default_dpi * aspect[1] / aspect[0])
else:
ndpi = (default_dpi, default_dpi)
# In python3, the returned dpi value for some tiff images will
# not be an integer but a float. To make the behaviour of
# img2pdf the same between python2 and python3, we convert that