PhotoQt is now available as AppImage! You can download the latest AppImage file right here. It is highly recommended to verify the integrity of your download by comparing it to these checksums.
Once downloaded, use a terminal to mark the file as executable:
$ chmod +x ./PhotoQt-4.2.AppImage
Now everything is ready. Execute the file either from your favorite file manager or directly from the command line:
The Flatpak package is a recommended alternative, offering support for a wider range of image formats and a more complete set of features.