This is a quick and dirty solution for an unanimated custom splash screen during boot.
This solution works but there are a few seconds of text shown before the boot image appears.

First of all, you need to install fbi:

 

Copy your custom splash image to /etc/ and name it “splash.png“. Presumably the resolution to use is 1920x1080px.

Next, create an init.d script called “asplashscreen” in “/etc/init.d/“. The file name is “asplashscreen” with an “a” at the beginning to be sure it starts first.

 

Paste the following into the text editor:

 

Exit and save the file as: /etc/init.d/asplashscreen

If copying and pasting via SSH check it has pasted in correctly. # lines and the esac line could be altered and have to be modifying back to be correct.

Then make that script executable and install it for init mode rcS:

 

Reboot and watch your custom splash screen: