@vsub there's no need for magic the negative I posted was hex edited. It's like I said, file need to be smaller and be in png format. only that matters.
Here's a short guide as it bugs me when people call simple things "impossible"
Open pcsx2 executable in hex editor, and search for this array of bytes:
(which basically is the beginning of background png;].
now create an png file with size LESS(yes could be exact, but making it exact is bothersome and NOT required at all) than 67.12KB (which is the original) could be even half of that value, it doesn't matter;], after creating it, also open it in hex editor. Also original png is 380x180 res, but you can make it different, only file size and format matters.
Copy all bytes of the png file and check how much there are of them(personally I use hex workshop it shows that clearly)
go to the result from the step 1 and select exactly same amount of bytes from the result adress, as the png file which you just copied has.
paste it, save the exe(maybe to other name just in case you did something badly as that would corrupt your exe;]) and if everything was done right, run the pcsx2 by it and be happy with different image.
Here's something in case Ice Queen Zero wants to try xD ...
(Just an RGB <> GBR color swap of the original.)