Bug#1092943: loupe: Images with transparent backgrounds displayed in an unusable way

[Richard]

Package: loupe
Version: 47.2-2
Severity: normal

Dear Maintainer,

loupe has a serious issue, making it virtually unusable with most if not all images containing a transparent background, as it relies on a broken algorithm to automatically adapt what color loupe shows behind the image [1]. Making matters even worse, not using the dark theme in Gnome will still cause this issue, as the author of loupe decided to adhere to the HIG recommendation to always default to a dark background for apps displaying rich content [2]. Without "gsettings set org.gnome.desktop.interface color-scheme prefer-light" it's impossible to work around the issue, affecting all users of Gnome that haven't manually installed an alternative image viewer and made it the default. The issue is also still present in v48.alpha from the gnome-nightly flatpak remote.

[1]: https://gitlab.gnome.org/GNOME/loupe/-/issues/139
[2]: https://developer.gnome.org/hig/guidelines/ui-styling.html#light-and-dark-ui-styles


-- System Information:
Debian Release: trixie/sid
   APT prefers testing
   APT policy: (990, 'testing'), (50, 'experimental'), (50, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 6.12.9-amd64 (SMP w/16 CPU threads; PREEMPT)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages loupe depends on:
ii  dconf-gsettings-backend [gsettings-backend]  0.40.0-4+b3
ii  glycin-loaders                               1.1.2+ds-4
ii  libadwaita-1-0                               1.6.2-1
ii  libc6                                        2.40-5
ii  libcairo2                                    1.18.2-2
ii  libfontconfig1                               2.15.0-1.1+b1
ii  libgcc-s1                                    14.2.0-12
ii  libglib2.0-0t64                              2.82.4-1
ii  libgraphene-1.0-0                            1.10.8-4
ii  libgtk-4-1                                   4.16.12+ds-1
ii  libgweather-4-0t64                           4.4.4-1
ii  liblcms2-2                                   2.16-2
ii  libseccomp2                                  2.5.5-2

loupe recommends no packages.

loupe suggests no packages.

-- no debconf information