The file 'knoppix-data.img' or in case of encryption 'knoppix-data.aes' is always compressed! Have a look at it with midnightcommander.

If you boot Knoppix, it is mounted (and decompressed) via '/dev/loop0' to '/KNOPPIX-DATA'. If you boot with cheatcode "noimage" nothing happens with '..img' or '..aes'

Greetings Werner * http://www.wp-schulz.de/knoppix/summary.html
Own Rescue-CD with Knoppix (Knoppix V6.7.1 remaster)