Search "Diskinternals Linux Reader" on Google, download and install it.
Open the program and mount image, choose your ext4 file, that's all
Inviato dal mio GT-I9505
Doesn't work. When you open system.img.ext4 with it, it errors out saying "File system not supported." There's an extra step for Samsung firmwares, unfortunately the sgs2ext4.jar tool posted around XDA no longer works (it's over two years old anyway).
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