I understand that for historic and technical reasons, a standard display resolution of 640×480 was both expected and desirable for high compatibility and minimal resource usage.
As we approach a world where 16:9 or varied aspect ratio displays and high dpi or crude pixel doubling work around are becoming common place, I wanted to ask for posterity (when and) how can grub be configured with a wallpaper image larger than 1024×768?
At time of writing, taken from the debian wiki, a grub2 wallpaper image cannot be larger than 1024×768px, and it will (configured by default) be stretched to match your gfx resolution.
One way to give the illusion of a 16:9 grub wallpaper is to take an existing 16x9 wallpaper and scale it to the 4:3 image of size 1024x768, and set the grub gfx mode for example to GRUB_GFXMODE=1920x1080, when grub loads and stretches that image its aspect ratio will appear similar to the original.
Debian wiki except from time of writing:
GRUB v2 Splash Image
Grub2 is ready to display a graphical screen (GRUB v1.95 is also known as “version 2”, it's called grub by upstream ).
Image constraints :
- file format : TGA (uncompressed or RLE 1 ).
- 640×480 pixels (you can change this, for instance 1024×768).
- 24 and 32bits True colors : 24 bits = 16 million colors ; 32 bits = 16 million colors + 8 bits for alpha channel).
- The text layout is fixed (including the frame).
- Specify a black background in "set menu_color_normal", in order to make GRUB menu transparent.
