Recently I've started the endeavor to add a custom boot logo to my iPhone 4 using the techniques used with the new RC5 GreenPois0n.

So far I've been successful at figure how to get the BootLogo package from Cydia, and even SSH into the iPhone so I could load my own custom Boot Logo.

Although I've run into one issue. The coloring on my Boot Logo shows up differently than it should actually look. A few of the blue colors have turned orange. I'm assuming it's a formatting issue of the PNG file type using, but I'm not sure which exact PNG format is appropriate.

What PNG file type should I be using for my iPhone 4 iOS 4.2.1 Boot Logo on my retina display?