[Pkg-gmagick-im-team] Bug#974750: imagemagick-6.q16: Convert to .tga (Targa) now flips image upside-down

[Matija Nalis]

Package: imagemagick-6.q16
Version: 8:6.9.11.24+dfsg-1+b2
Severity: normal
X-Debbugs-Cc: mnalis-debianbug at voyager.hr

Dear Maintainer,

Converting to .tga (Targa) format now (Unstable) flips image upside-down.

It worked fine in Buster version (imagemagick 8:6.9.10.23+dfsg-21+deb10u1)
and it still works fine with graphicsmagick version in Unstable 
(graphicsmagick 1.4+really1.3.35+hg16348-1+b1). So this is regression.

Resulting .tga image created by Sid version of imagemagick
8:6.9.11.24+dfsg-1+b2 is consistently vertially flipped when viewed in all
viewers (gimp, xzgv, xli, mirage, and even imagemagick's own display(1))

One can kludge around by using "convert-im6 -flip" to get correct image, but
it is wrong behaviour.

sid% convert-im6.q16 Graphics_Assets/intro5.png /tmp/imagemagick_sid.tga 
sid% gm convert Graphics_Assets/intro5.png /tmp/graphicsmagick_sid.tga
sid% convert-im6 -flip Graphics_Assets/intro5.png /tmp/imagemagick_flip_sid.tga
sid% md5sum /tmp/*_sid.tga                                                     
81d1f1a2c481958c5af09c3985615ed0  /tmp/graphicsmagick_sid.tga
81d1f1a2c481958c5af09c3985615ed0  /tmp/imagemagick_flip_sid.tga
d948d272cbb2ab8230ee0b185414e6c6  /tmp/imagemagick_sid.tga

buster% convert-im6.q16 Graphics_Assets/intro5.png /tmp/imagemagick_buster.tga
buster% md5sum /tmp/imagemagick_buster.tga
81d1f1a2c481958c5af09c3985615ed0  /tmp/imagemagick_buster.tga

It happens with any source file; I've tried with several .png and .jpg files
as source, for example /usr/share/desktop-base/spacefun-theme/login/sddm-preview.jpg
or /usr/lib/libreoffice/share/template/wizard/bitmap/euro_2.png

Bug only happens when converting to .tga (converting to png/jpg/tiff works
normally)

Of course, the nature of bug is such that if you convert from .png to .tga,
and then back from .tga to .png, the seconds .png will again look correct,
as bug happened twice and thus fixed itself again!

-- Package-specific info:
ImageMagick program version
---------------------------
animate:  ImageMagick 6.9.11-24 Q16 x86_64 20200718 https://imagemagick.org
compare:  ImageMagick 6.9.11-24 Q16 x86_64 20200718 https://imagemagick.org
convert:  ImageMagick 6.9.11-24 Q16 x86_64 20200718 https://imagemagick.org
composite:  ImageMagick 6.9.11-24 Q16 x86_64 20200718 https://imagemagick.org
conjure:  ImageMagick 6.9.11-24 Q16 x86_64 20200718 https://imagemagick.org
display:  ImageMagick 6.9.11-24 Q16 x86_64 20200718 https://imagemagick.org
identify:  ImageMagick 6.9.11-24 Q16 x86_64 20200718 https://imagemagick.org
import:  ImageMagick 6.9.11-24 Q16 x86_64 20200718 https://imagemagick.org
mogrify:  ImageMagick 6.9.11-24 Q16 x86_64 20200718 https://imagemagick.org
montage:  ImageMagick 6.9.11-24 Q16 x86_64 20200718 https://imagemagick.org
stream:  ImageMagick 6.9.11-24 Q16 x86_64 20200718 https://imagemagick.org

-- System Information:
Debian Release: bullseye/sid
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 5.9.0-2-amd64 (SMP w/1 CPU thread)
Locale: LANG=C, LC_CTYPE=C.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages imagemagick-6.q16 depends on:
ii  hicolor-icon-theme     0.17-2
ii  libc6                  2.31-4
ii  libmagickcore-6.q16-6  8:6.9.11.24+dfsg-1+b2
ii  libmagickwand-6.q16-6  8:6.9.11.24+dfsg-1+b2

Versions of packages imagemagick-6.q16 recommends:
pn  ghostscript                  <none>
pn  libmagickcore-6.q16-6-extra  <none>
pn  netpbm                       <none>

Versions of packages imagemagick-6.q16 suggests:
pn  autotrace               <none>
pn  cups-bsd | lpr | lprng  <none>
ii  curl                    7.72.0-1
pn  enscript                <none>
pn  ffmpeg                  <none>
pn  gimp                    <none>
pn  gnuplot                 <none>
pn  grads                   <none>
pn  graphviz                <none>
ii  groff-base              1.22.4-5
pn  hp2xx                   <none>
pn  html2ps                 <none>
pn  imagemagick-doc         <none>
pn  libwmf-bin              <none>
pn  mplayer                 <none>
pn  povray                  <none>
pn  radiance                <none>
pn  sane-utils              <none>
pn  texlive-base-bin        <none>
pn  transfig                <none>
pn  ufraw-batch             <none>
ii  xdg-utils               1.1.3-2

-- no debconf information