HOWTO: Replace standard GRUB splash screen
1) Install additional packages
zypper in gfxboot, gfxboot-devel, qemu, syslinux
2) Unpack gfxboot archive
cpio -i </boot/message
3) Store backup copy of standard GRUB splash image
cp back.jpg /tmp
4) Create new splash image (800x600, JPG, back.jpg)
cp custom.jpg back.jpg
5) Replace splash screen background image
gfxboot --add-files back.jpg
6) Test changes made
gfxboot --preview