Convert PNG from premultiplied-alpha to conventional alpha transparancy?

I'm having a really hard time working with some source images in PNG format that h开发者_高级运维ave premultiplied alpha because most tools simply do not support it correctly.

Is there anything out there that can do a "best guess" conversion to a more conventional PNG?

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If by "premultiplied alpha" you mean iOS's PNG derivative, then you can convert them back to PNGs with pngdefry.

Standard PNGs never use premultiplied alpha.