Bug#930807: poppler-utils: pdftoppm "-png -scale-to 1920" generates PNG with 1921 pixels in width

[Anthony Fok]

Package: poppler-utils
Version: 0.71.0-5
Severity: normal

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The current pdftoppm sometimes creates PPM or PNG with a width that is
off-by-one, e.g.:

  $ pdftoppm Lauda_Sion.pdf Lauda_Sion -png -scale-to 1920
  $ file Lauda_Sion_01.png
  Lauda_Sion_01.png: PNG image data, 1921 x 1080, 8-bit colormap, non-interlaced

If I recall correctly, pdftoppm used to create output images with
exactly 1920 pixels in width, so this could be a regression, but my
memory is vague and I haven't done extensive testing yet.

  -scale-to 19200 → 19201
  -scale-to 3840 → 3841
  -scale-to 1920 → 1921
  -scale-to 960 → 961
  -scale-to 480 → 481
  -scale-to 240 → 241
  -scale-to 120 → 121
  -scale-to 60 → 61
  -scale-to 30 → 31
  -scale-to 15 → 16

The PDF file from which I observe this has a page size of 659.52 x 370.98 pts.

I created another 16:9 PDF file with page size of 1152 x 648 pts for
testing, but in this case, pdftoppm generates PNGs with perfect 1920x1080 dimensions.

Thanks,

Anthony

- -- System Information:
Debian Release: 10.0
  APT prefers unstable
  APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.19.0-5-amd64 (SMP w/4 CPU cores)
Kernel taint flags: TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=en_CA.UTF-8, LC_CTYPE=en_CA.UTF-8 (charmap=UTF-8), LANGUAGE=en_CA.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages poppler-utils depends on:
ii  libc6         2.28-10
ii  libcairo2     1.16.0-4
ii  libfreetype6  2.9.1-3
ii  liblcms2-2    2.9-3
ii  libpoppler82  0.71.0-5
ii  libstdc++6    8.3.0-7

poppler-utils recommends no packages.

poppler-utils suggests no packages.

- -- no debconf information

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