[Bug 1838860] Re: convert translates upside down some picture when converting from jpg to tga

[Thomas DEBESSE]

Bad news, sometime the converted png from jpg displays properly but is
then set upside-down when converting from png to tga.

I updated the screenshot of the bug:
https://dl.illwieckz.net/b/imagemagick/bugs/convert-jpg-to-tga-upside-down/convert-jpg-to-tga-upside-down.png

And the script to reproduce:
https://dl.illwieckz.net/b/imagemagick/bugs/convert-jpg-to-tga-upside-down/convert-jpg-to-tga-upside-down.sh

Which now looks like this:

for i in *.jpg
do
    n="$(basename "${i}" '.jpg')"
    convert "${i}" "${n}.png"
    convert "${i}" "${n}.tga"
    convert "${n}.png" "${n}.png.tga"
done

When I said converting from jpg to png to tga worked, in fact I had only
tested with one file. It's not always true. With the provided
"noships.jpg" file, the bug is carried over the png.

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https://bugs.launchpad.net/bugs/1838860

Title:
  convert translates upside down some picture when converting from jpg
  to tga

Status in imagemagick package in Ubuntu:
  New

Bug description:
  When I convert some jpg image to tga format, the tga image is upside
  down.

  The bug only appears with some jpg images, not all. I can convert
  thousands of jpg images without problems but in some rare images the
  bug occurs.

  You can find three jpg images that are known to fail there:
  https://dl.illwieckz.net/b/imagemagick/bugs/convert-jpg-to-tga-upside-down/convert-jpg-to-tga-upside-down-samples.zip
  I also attach to this bug report the smallest sample I have.

  If I convert from jpg to png, the png is ok
  If I convert from jpg to png then from png to tga, the tga is ok
  If I convert from jpg to tga, the tga is upside down

  You can reproduce by downloading the samples, then run this code in
  the directory containing the samples:

  for i in *.jpg
  do
      n="$(basename "${i}" '.jpg')"
      convert "${i}" "${n}.png"
      convert "${i}" "${n}.tga"
  done

  You can have a look of the result there:
  https://dl.illwieckz.net/b/imagemagick/bugs/convert-jpg-to-tga-upside-down/convert-jpg-to-tga-upside-down.png

  You can also download this script there:
  https://dl.illwieckz.net/b/imagemagick/bugs/convert-jpg-to-tga-upside-down/convert-jpg-to-tga-upside-down.sh

  ProblemType: Bug
  DistroRelease: Ubuntu 19.04
  Package: imagemagick-6.q16 8:6.9.10.14+dfsg-7ubuntu2.2
  ProcVersionSignature: Ubuntu 5.0.0-21.22-generic 5.0.15
  Uname: Linux 5.0.0-21-generic x86_64
  ApportVersion: 2.20.10-0ubuntu27.1
  Architecture: amd64
  CurrentDesktop: GNOME
  Date: Sun Aug  4 01:59:00 2019
  SourcePackage: imagemagick
  UpgradeStatus: No upgrade log present (probably fresh install)
  modified.conffile..etc.default.apport: [modified]
  mtime.conffile..etc.default.apport: 2018-06-16T17:39:00.798346

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