This problem was discussed quite a lot a few years back.
For my own needs I use a utility that I call "kapview". It's just a simple shell script using imgkap and whatever program you have installed for picture viewing.
imgkap "$1" tmp.png
Put the script somewhere in your PATH and make it executable.
Just click on the kapfile you would like to view......
This example is Linux
, but the idea should be possible to implement on any system.