Optical Disc Images

A disc image is a single file containing the complete contents and structure representing a data storage medium, such as a CD/DVD/Blu-ray disc.

An optical disc image is usually created by making a complete sector-by-sector copy of the source medium and thereby perfectly replicating the structure and contents of a storage device. Disc images are mainly used for backup and disc cloning. The most common disc image format is ISO.

An ISO image is an archive file of an optical disc, composed of the data contents of every written sector of an optical disc, including the optical disc file system. ISO image files typically have a file extension of .iso. The data are stored in an uncompressed format, so it is a true digital copy of the original. These properties make ISO images an attractive alternative to physical media for the distribution of software, as it is simple to transfer over the Internet. The most important feature of an ISO image is that it can be easily rendered or burned to a CD, DVD or BD by using media authoring or disc burning software. It can also be opened using any file archiver.

ISO images are not able to store and recreate audio CD discs, due to the fact that audio CD discs do not use a computer file system. To store an accurate copy of an audio CD disc, a different image format must be used, such as BIN/CUE.