I had written a tutorial about how to add splash image for grub 2.Today I found couple of Grub2 splash image and they are very easy to add into your grub because the deb packages provided.
Choose one image and download the package,then just double click to install and finally reboot.
If it doesn’t work,try to install in command line:
sudo dpkg -i package_name_here
And for amd64 machine,try following to install those packages for i386:
sudo dpkg -i --force-architecture filename.deb