The theme has low contrast and is abstract in order to not be boring on the long term or agressive for the user's eyes.
Done with the Gimp.
No other source image than the Debian logo.
The original picture has been done in 1920x1080 in order to be resized more easily.
Latest version (v2, Stretch)
This is a modified version for the Stretch release.
I provide only the main wallpaper, in 2 versions: red and blue.
Source: xcf file (14MB)
As GRUB, ?SysLinux, ... need a low definition (colors between from 4 to 24bits), the picture has a simpler design for these cases. It need only two colors (800*600 because it's a Grub requirement):
If it's possible to change the text color I would prefer to have the grub output in black so the swirl could be in grey like the main wallpaper.
If needed for others proposals, these is a template to fake GRUB (png, source) based on 'Growing' theme.
Source: xcf file (10MB)
Author: Stéphane Blondon
Copyright: 2016, Stéphane Blondon <email@example.com>, License: GPL-2.0+ for every version of the theme