Using KDE:Qt58 repository:

Trying to view JPEG-2000 images with Qt5/KF5 applications (Dolphin, Gwenview,
etc.) fails, because the QtImageFormats plugins are not compiled with support
for jasper library.

As far as I understand, jasper was long unmaintained, but recently got several
handful of security issues applied, so jasper support can be safely enabled
again.

JPEG-2000 test image: http://www.fnordware.com/j2k/relax.jp2

Related: https://bugs.kde.org/show_bug.cgi?id=375641

Reporting to KDE maintainers, because I guess they are responsible for Qt
packages; if not, please reassign.