You will have a large ISO file. When you boot from this ISO (in a VM or burned to a disc), it launches the Acronis recovery environment and automatically detects your TIBX backup, allowing you to restore it. This is not a file-accessible ISO ; it is a recovery tool ISO.
If you don't need a bootable ISO—you just want the files (documents, photos, videos) contained in the TIBX to be available as read-only—this is the easiest method. convert tibx to iso