Uncrush PNG image on ubuntu?

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IPA image uses pngcrush to compress PNG image, but I want to uncrush a PNG image on Ubuntu.

Can anyone give me any idea?

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Jongware On

The standard PNG utility pngcrush has been modified by Apple, which makes it produce technically invalid PNGs: a new chunk is inserted before the mandatory first chunk IHDR, RGB(A) order of pixel data is inverted, and RGB pixels get premultiplied with their alpha.

Hence, I'd rather call these PNGs "fried", rather than just "crushed".

Try my own pngdefry. The source code is written on a Mac OSX machine but it should be compilable for other OSes as well; it's pretty straightforward C code.