after the update from 16.04 to 18.04, okular stopped showing dds format images. "unsupported image format "
update 2 system desktop and notebook

screenshot
https://www.dropbox.com/s/yv0gr3bapqss0v6/Screenshot_20181024_203607.png?dl=0

Okular is not an image viewer, even if it can show some images using the support provided by Qt.

So please try to see if other Qt-based viewers can show it. Your system most likely miss a Qt plugin which supports that format.

I did not know about that format, but this page seems to explain the problem:
http://doc.qt.io/qt-5/qtimageformats-index.html

Note: For security reasons, the Direct Draw Surface (DDS) handler is not built by default since Qt 5.8. Users who still want this handler can build it from the source project.

tl;dr not an Okular issue, but a Qt issue, and in general please use other programs for images.

from https://metadata.neon.kde.org/appstream/html/bionic/main/metainfo/okular.html

Code: Select all

org.kde.okular-kimgio - 4:18.08.2-0xneon+18.04+bionic+build11

Code: Select all

Provides:
  mimetypes:
  - image/bmp
  - image/x-dds
  - image/x-eps
  - image/x-exr
  - image/gif

There are no differences from 16.04 in metainfo.
installed version 4:18.08.2-0xneon+18.04+bionic+build10
previous versions had all the same description.
karc tries to show dds only in the okular

before updating to 18.04 the same okular normally displayed DDS, no problem.

Please re-read my answer. It depends on the support of dds in Qt, which is now disabled by default.

You could argue that the metadata should be changed by default, but then also the packagers should make sure that the support matches the image formats supported by the Qt version provided by the distribution.