Old Prussian Script?

[Osweo]

Soten's signature pic has been annoying me;
http://www.wcer.org/members/europe/lithuania/perkun.gif

A Lithuanian site reckons that the image is

The flag of Old Prussians with three main gods: Perkūnas, the god of thunder, in the center, Patrimpas, the god of spring and fertility, at the right, and Pykuolis, the god of the dead and underground, at the left. The script is in the Old Prussian (from S. Grunau, Preussische Chronik, Hrg. von W. Perlbach, vol. 1-3, 1876-1895).
http://www.lithuanian.net/mitai/cosmos/baltai5.htm

Is this correct?

I look and I look at the text, trying to find three separate names all beginning with the same letter, but I can't make it out.

What script is this? Where can I find a key?

[Jarl]

Nonsense. Nothing survived from the Old Prussian culture and folklore. Apart of the apart from singular names, scripts and phrases. Prussian religion has been reconstructed mostly basing on Lithuanian folklore. The image must come from some XVII century German source:

http://www.baltische-rundschau.eu/2009/03/19/geschichte-der-prusen-bis-zum-aufstellen-ihrer-%E2%80%9Egrundrichtlinien%E2%80%9C-523-nchr/

I very much doubt it is in Prussian. And for certain there were no "Prussian flags" as Prussians did not even form coherent centralised tribes.