What Is a CD Disc Image?

A disc image is a file or collection of files representing the contents and, depending on the format, structure of an optical disc. Images can be useful for preservation and later analysis.

ISO images

The Library of Congress describes ISO images as archives containing the content from or destined for an optical disc. Not every optical-disc type is fully represented by a simple ISO.

BIN/CUE

For data discs, an ISO may preserve the filesystem and files. Audio CDs and unusual optical formats can require other representations to retain the relevant disc structure.

Filesystem images

The correct image format should therefore be selected according to the source and the information that needs to be preserved.

Audio CD considerations

An image should be accompanied by technical and descriptive metadata and verified with checksums.

Preservation use

Retain extracted access files separately when convenient use is required.

Reference guidance: This article is informed by optical-media preservation guidance from the U.S. National Archives and the Library of Congress Recommended Formats Statement. Where appropriate, the article distinguishes preservation guidance from practical extraction procedures.