It seems that the Debian `qt5-image-formats-plugins` package does not
support JPEG2000/JP2 images, in spite of this format being supported by
Qt [1] through the JasPer Image Processing/Coding Tool Kit [2]. This
results in QImage-based end-user applications such as Gwenview not
supporting this popular image format, although technically possible.

In order to add JP2 support, `qt5-image-formats-plugins` would need to
be built with JasPer, which would first require packaging the latter in
Debian. The Ubuntu repository already contains a package named `jasper`,
but it does something completely different [3], so the image processing
JasPer package may need to be named differently.

JasPer used to be affected by security issues [4], but as of the day of
writing all known CVEs are fixed [5], and JasPer continues to be
maintained by the original author Michael Adams and contributors [6]
(latest version 2.0.33 released on 2021-08-01 [7]).

Note that the author of this bug report does not use Debian itself, but
the Ubuntu-based KDE Neon [8]. However, judging by the list of
dependencies [9], `qt5-image-formats-plugins` is not built with JasPer
and thus without JP2 support in Debian. Therefore, this report should
only be seen as a notification to the Debian packaging team in order to
promote support for the JP2 format.

[1]
https://github.com/qt/qtimageformats/blob/dev/src/plugins/imageformats/jp2/qjp2handler.cpp
[2] https://github.com/jasper-software/jasper
[3] https://packages.ubuntu.com/hirsute/jasper
[4] https://github.com/jasper-software/jasper/issues/208
[5]
https://github.com/jasper-software/jasper/issues/208#issuecomment-665471904
[6] https://github.com/jasper-software/jasper/graphs/contributors
[7] https://github.com/jasper-software/jasper/releases/tag/version-2.0.33
[8] https://bugs.kde.org/show_bug.cgi?id=441673
[9] https://packages.debian.org/bullseye/qt5-image-formats-plugins

Hi Manuel,

thanks for your report and detailed explanations.

Yes, that is the first step. There has been a jasper package back in
Jessie times but it seems it has been removed.

Unfortunately, the qt5-image-formats-plugins sources don't support
openjp2 library, and only accept jasper.

I am not sure whether we want to package jasper here in the Qt/KDE team.

Best

Norbert

Hello Norbert,

thanks for your response.

 > Yes, that is the first step. There has been a jasper package back in
 > Jessie times but it seems it has been removed.
 > [...]
 > I am not sure whether we want to package jasper here in the Qt/KDE team.

Yeah, it had been removed due to isuues about security and maintenance
[1]. However, now that JasPer is actively maintained again, these
concerns should mostly be allayed. KDE Neon just added the JasPer
package back [2], and Arch had kept it all the time [3]. So personally I
would think it reasonable to package JasPer in Debian again. There may
also be other packages aside from `qt5-image-formats-plugins` that could
profit from JasPer.

 > Unfortunately, the qt5-image-formats-plugins sources don't support
 > openjp2 library, and only accept jasper.

You're right. Is TQtC aware of the past issues with JasPer? Maybe
someone should file an issues at `bugreports.qt.io` to request porting
to openjpeg2?

Kind regards,
Manuel

[1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=818209
[2] https://bugs.kde.org/show_bug.cgi?id=441673#c11
[3] https://bugs.archlinux.org/task/64655