[Pkg-gnome-extras-maintainers] Bug#1131496: gimp: Threshold creates perfect image, conversion to 1-bit mode destroys it

[Axel Stammler]

Package: gimp
Version: 3.0.4-3+deb13u7
Severity: normal
X-Debbugs-Cc: axst at users.sourceforge.net

Dear Maintainer,

after the upgrade to Trixie, if I convert a colour image to a 2-colour black and white one
using Threshold, I can choose the perfect threshold as I used to. Converting this image to
1-bit mode puts the threshold at a different point, resulting in a loss of content because
the image is then too bright (or possibley too dark). The effect is always the same,
independent of the actual threshold used.

This seems to be a new problem as these two steps combined perfectly in Bookworm.


-- System Information:
Debian Release: 13.4
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 6.12.74+deb13+1-amd64 (SMP w/4 CPU threads; PREEMPT)
Locale: LANG=en_IE.UTF-8, LC_CTYPE=en_IE.UTF-8 (charmap=UTF-8), LANGUAGE=en_IE:en
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages gimp depends on:
ii  gimp-data            3.0.4-3+deb13u7
ii  gir1.2-gimp-3.0      3.0.4-3+deb13u7
ii  graphviz             2.42.4-3
ii  libaa1               1.4p5-51.1+b1
ii  libappstream-glib8   0.8.3-1
ii  libarchive13t64      3.7.4-4
ii  libasound2t64        1.2.14-1
ii  libbabl-0.1-0        1:0.1.114-2
ii  libbz2-1.0           1.0.8-6
ii  libc6                2.41-12+deb13u2
ii  libcairo2            1.18.4-1+b1
ii  libcfitsio10t64      4.6.2-2
ii  libfontconfig1       2.15.0-2.3
ii  libfreetype6         2.13.3+dfsg-1+deb13u1
ii  libgcc-s1            14.2.0-19
ii  libgdk-pixbuf-2.0-0  2.42.12+dfsg-4
ii  libgegl-0.4-0t64     1:0.4.62-2+deb13u2
ii  libgexiv2-2          0.14.3-1+b1
ii  libgimp-3.0-0        3.0.4-3+deb13u7
ii  libglib2.0-0t64      2.84.4-3~deb13u2
ii  libgomp1             14.2.0-19
ii  libgs10              10.05.1~dfsg-1+deb13u1
ii  libgtk-3-0t64        3.24.49-3
ii  libgudev-1.0-0       238-6
ii  libharfbuzz0b        10.2.0-1+b1
ii  libheif1             1.19.8-1
ii  libjpeg62-turbo      1:2.1.5-4
ii  libjson-glib-1.0-0   1.10.6+ds-2
ii  libjxl0.11           0.11.1-4
ii  liblcms2-2           2.16-2
ii  liblzma5             5.8.1-1
ii  libmypaint-1.5-1     1.6.0-4
ii  libopenexr-3-1-30    3.1.13-2
ii  libopenjp2-7         2.5.3-2.1~deb13u1
ii  libpango-1.0-0       1.56.3-1
ii  libpangocairo-1.0-0  1.56.3-1
ii  libpangoft2-1.0-0    1.56.3-1
ii  libpng16-16t64       1.6.48-1+deb13u3
ii  libpoppler-glib8t64  25.03.0-5+deb13u2
ii  librsvg2-2           2.60.0+dfsg-1
ii  librsvg2-common      2.60.0+dfsg-1
ii  libstdc++6           14.2.0-19
ii  libtiff6             4.7.0-3+deb13u1
ii  libwebp7             1.5.0-0.1
ii  libwebpdemux2        1.5.0-0.1
ii  libwebpmux3          1.5.0-0.1
ii  libwmf-0.2-7         0.2.13-1.1+b3
ii  libwmflite-0.2-7     0.2.13-1.1+b3
ii  libx11-6             2:1.8.12-1
ii  libxcursor1          1:1.2.3-1
ii  libxext6             2:1.3.4-1+b3
ii  libxfixes3           1:6.0.0-2+b4
ii  libxmu6              2:1.1.3-3+b4
ii  libxpm4              1:3.5.17-1+b3
ii  python3-gi           3.50.0-4+b1
ii  xdg-utils            1.2.1-2
ii  zlib1g               1:1.3.dfsg+really1.3.1-1+b1

Versions of packages gimp recommends:
ii  ghostscript  10.05.1~dfsg-1+deb13u1

Versions of packages gimp suggests:
pn  gimp-data-extras             <none>
ii  gimp-help-en-gb [gimp-help]  3.0.0-4
ii  gvfs-backends                1.57.2-2
ii  python3                      3.13.5-1

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