If it is REALLY an image backup then it will contain everything.. BUT as been mentioned they are scattered in different places…
WIN 7
HKEY_LOCAL_MACHINE SYSTEM : system32configsystem
HKEY_LOCAL_MACHINE SAM : system32configsam
HKEY_LOCAL_MACHINE SECURITY : system32configsecurity
HKEY_LOCAL_MACHINE SOFTWARE : system32configsoftware
HKEY_USERS UserProfile : winntprofilesusername
HKEY_USERS.DEFAULT : system32configdefault
Never tried to open these directly on another HDD.
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If the backup is just Data to the NAS then it won’t have system files.
Not sure if this helps but I guess you can try and let us know,,,,,,