I have never tinkered with Samsung devices. I can only easily do this if a few things are the same as on HTC devices, which I don't know whether they are:
- same naming of block devices in the device tree
- same recovery scripts
- same mechanism for storing the splash
If those are all the same, then all I need to know is the partition number and the screen resolution.
I don't own the device so I can not do the research. You can do the research.
Basically: extract the first X bytes (depends on screen resolution: X = w * h * 2) of each partition that is big enough but not ridiculously big and see if it looks like your splash.
This is a post of mine where
I guide someone through the steps for another device I don't own. However, this is an HTC device so things will be different for you.
I can guide you more but you have to know some basics and be able to get an adb shell and be comfortable typing commands and following instructions.