HACKTUX notes from the trenches

So, you want to change your Grub background or wallpaper?
First, find an image that is at least 640x480. Open the image in GIMP.

gimp grub_background.jpg

Now, resize the image to 640x480 if needed ( Image -> Scale Image... )

And then save the image as an XPM ( File -> Save As... ).

Be sure to save the file as an X PixMap image (.xpm).

Compress the file and place it on your /boot partition, inside the grub folder.

gzip grub_background.xpm
sudo cp grub_background.xpm.gz /boot/grub/

Finally, edit your /boot/grub/grub.conf and add or replace the splashimage entry with your custom background.

splashimage=(hd0,0)/grub/grub_background.xpm.gz

Reboot to test your changes. If the Grub background appears like television snow, check that the image size is exactly 640x480.