Question about the Supplemental Wallpaper Submission Guidelines

[Ryan Lerch]

The guidelines[1] for the supplemental wallpaper submissions state that 
you need permission from the author to submit the file. Does anyone know 
the reasoning for this? Does it also apply to images that are in the 
Public Domain?

I ask because there are many many awesome images in places like the NASA 
image library that are public domain. These would be nice to source and 
include in the submissions. Do I need to contact NASA to see if their 
public domain images are okay for use as a Fedora wallpaper?

Same question if i source an image that is already licensed CC-BY-SA. Do 
i need to contact the artist directly? or does the their choice of 
licence imply permission for use (and consequently for me to submit).

cheers,
ryanlerch

[1] - 
https://fedoraproject.org/wiki/F20_Artwork/Submissions/Supplemental_Wallp...