How to change Live CD splash screen

I'm remastering the ubuntu CD, I've changed some files in the isolinux folder (access.pcx, blank.pcx, gfxboot.cfg) and I have been able to change the first screen (background color to green):

But I can't change the second screen.

I made my own plymouth-theme package, and removed the plymouth-theme-ubuntu-text package. But this standard ubuntu screen is still displayed.

After installation, my own plymouth theme is well displayed.

So, I'm lost, is this screen related to plymouth? (if so, how can it be displayed after removing plymouth-theme-ubuntu-text) Or is it another file to modify?

I found my answer in backtrack linux forums. And since I set up the bounty I would like to explain a little bit what my problem was and how it got solved.

I was trying to customize Ubuntu/KUbuntu 10.04 Live CD and I couldn't figure out how to change the splash screen that shows after isolinux.

Changing playmouth theme available on the extracted filesystem.squashfs at /lib/plymouth/themes/ didn't do the trick.

So I found this message stating that the splash screen files used by the Live CD to boot reside in casper/initrd.lz.

So, if you are interested to know how to extract and reconstruct this file, read the end of the section 5.7.1. Quote:

To unpack the initrd.lz file, you need to do this:

cd extract-cd/casper
mkdir lztempdir
cd lztempdir
lzma -dc -S .lz ../initrd.lz | cpio -imvd --no-absolute-filenames

And to re-create the initrd.lz file:

cp ../initrd.lz ../inird.lz.orig
find . | cpio --quiet --dereference -o -H newc | lzma -7 > ../initrd.lz

Did you rebuild the initramfs that the liveCD uses when booting the rest of the environment to include your new plymouth theme? I suspect that is the missing step.