wrong fs type, bad option, bad superblock on /dev/sda, missing codepage or helper program, or other error code example

Example 1: wrong fs type, bad option, bad superblock on /dev/loop0, missing codepage or helper program, or other error+dd image

sudo mount -o rw -t ext4 /dev/mapper/loop0p2 mount_target/

Example 2: wrong fs type, bad option, bad superblock on /dev/loop0, missing codepage or helper program, or other error+dd image

sudo kpartx -a raspberry-backup-2014-04-10.img