Introduction

Digital content has taken over in most areas of commerce and entertainment. We take it for granted that documents, still images and video can be transmitted instantly to the other side of the world.This was not the case even 20 years ago. Back then the electronic transfer of content was limited to a few specialised applications. Radio and television could deliver live audio and video. The wireline photo had been in use since 1935, and the fax machine existed but was not in common use until international standards were developed. Financial data was transmitted by telex. The telegram was used for brief text messages.

This digital revolution has by no means replaced the earlier physical content. How many offices could be described as paperless? Any enterprise deploying digital asset management system will have large archives of physical content. The picture library will have filing cabinets full of transparencies; the television station may have climate-controlled warehouses full of analogue tapes and movie film. Pharmaceutical companies have to maintain thousands of documents relating to the approval of drugs. Every company will have contracts, maybe even sealed and tied with ribbons.

Physical content is usually found on four storage media: paper, photographic film, optical disk, and magnetic tape. Film includes photographs, movies, and microfilmed documents. In principal, all four formats can be easily ingested into a digital environment. Paper and film can be scanned. Tape and disk can be played back and converted to a digital stream.The potential problem with tape is...