atPeek is a small $4.99 utility that allows you to browse, view and export resources embedded in iPhone application .ipa files. Standard file formats like audio, plists and icons can be previewed with QuickLook and crushed iPhone PNG images or PVR textures can be converted back into standard PNGs with two custom developed plugins. Both individual assets can be exported or entire folders in bulk.
The flip side of being a useful little developer tool means it can also be used to extract copyrighted resources from other people’s apps. In fact, the main interface will happily list all of your apps from iTunes, ready to be delved into. So use responsibly, or if you’re a developer, consider encrypting your resources.
On a side note, did you know that iPhone application files are actually just ZIP files? rename them from .ipi to .zip and you can do the same without the pretty interface of atPeek.
(via Dylan Beadle on Twitter)
I bought atPeek, but did not work.
I try to explore many ipa with crushed PNg and PVR.
please have a try at http://iphone-ipk-png.raisedtech.com/, it online tool that helps you extract png file from ipk. it helps me a lot.