Here is all the information. I have been trying this loopback option for 3 days now. Not sure what I am doing wrong. I have two image files. One is 800MB the other is 19GB. When I use photo_rec I get a bunch of jpg and doc files which is a good sign.

contents of /etc/fstab:
# Added by KNOPPIX
/dev/sdb5 /media/sdb5 ext2 noauto,users,exec 0 0

root@Knoppix:/ramdisk/home/knoppix# mkdir /mnt/temp

root@Knoppix:/ramdisk/home/knoppix# mount -o loop -t ext2 /media/sdb5/hdb_rescue.img /mnt/temp

mount: wrong fs type, bad option, bad superblock on /dev/loop0,
missing codepage or other error
In some cases useful info is found in syslog - try
dmesg | tail or so

root@Knoppix:/UNIONFS/etc# dmesg | tail
sdb: Mode Sense: 33 00 00 00
sdb: assuming drive cache: write through
sdb: sdb1 sdb2 < sdb5 >
sd 3:0:0:0: Attached scsi disk sdb
usb-storage: device scan complete
EXT2-fs warning: mounting unchecked fs, running e2fsck is recommended
loop: AES key scrubbing enabled
loop: loaded (max 8 devices)
VFS: Can't find an ext2 filesystem on dev loop0.
VFS: Can't find an ext2 filesystem on dev loop0.