This is a suggestion for you. not a spam.

I've been developing a image viewer QuickViewer, by Qt toolkit under GPLv3.
https://github.com/kanryu/quickviewer

This application is currently for Windows, but it is designed to be easily ported to Unix environments.
I'm currently seeking help for porting to the Unix environments.

This is:

fast loading (with pre-loading)
fast drawing (with OpenGL)
spread viewing (for Digital Comics/Books)
read archives(zip/rar/7z/cbr/cbz)
to show Raw images(by digital cameras)

This is not:

image editor
animation viewer

If you desire, you can adopt QuickViewer as one of KDE's applications.
If this topic is evil for you, you do not mind to remove it.

Thanks.

The topic is not evil at all!
But I have to ask The Question: did you know Peruse?

https://peruse.kde.org/

tosky wrote:The topic is not evil at all!
But I have to ask The Question: did you know Peruse?

Thanks.
I didn't Peruse. It looks easy to use with a simple GUI as a comic leader

QuickViewer has officially responded to Linux in AppImage format.

https://github.com/kanryu/quickviewer/releases

Operation confirmed distributions are as follows:

Ubuntu
Kubuntu
Fedora Workstation