I would like to create a Desktop Background for my computer from an existing GigaPan. Is there any possebility to do that? Best would be like to select a region from any GigaPan, and then choose the resolution, like 1080×1920 or 1080×3840 (for two monitors). I hope, someone can help me, and sorry for my English, I come from Germany. Thanks a lot!

The simplest method I can think of is to:
1) Open your gigapan in a photo editor.
2) Create a crop rectangle with the correct ratio (1:1.78 for 1080×1920, 1:3.56 for 1080×3840)
3) Move and re-size (maintain the correct ratio) the crop rectangle to the section you like.
4) Complete the crop
5) Use your program’s image size features to downsize/downsample the cropped image to the final pixel value, width or height, you want. If you maintained the correct ratio, then it will downsize to the correct ratio for your monitor at the reduced pixel size.

You can do this in Photoshop, Gimp (free), Irfanview (free), and many more editors. If you use one of those three I can explain the process step by step.

bkaylor