This how to help you to add your own grub splash image(image in the boot menu).
1. Open any picture in GIMP
2. Resize canvas size to 640x480 ( If you are an expert you can add higher resolutions)
3. Now Save as .png or .tga format (in some versions jpg also works)
now copy the file to /boot/grub folder (eg: $sudo cp /home/shibu/xxx.tga /boot/grub)
For appearing new splashimage, you need to edit the file /etc/grub/05_debian_theme
$gksudo gedit /etc/grub.d/05_debian_theme
Now Find the following (it may be near 15th lane)
for i in {/boot/grub,/usr/share/images/desktop-base}/moreblue-orbit-grub.{png,tga} ; do
to replace 'moreblue-orbit-grub' with the name of your splashimage :
for i in {/boot/grub,/usr/share/images/desktop-base}/ceattingal.{png,tga} ; do
Now Run grub-mkconfig for writing the changes to grub-conf
$ sudo grub-mkconfig -o /boot/grub/grub.cfg
Now Everything Over, You can Reboot Now.