If you want to examine or extract the files contained in a disk image, you need extra software, as Windows cannot open an image by itself, and neither can most CD-writing software. An excellent third-party utility that can help with this is Smart Project's Isobuster software (www.isobuster.com), a freeware/shareware product that can read many image file formats and copy files out of them.

This can be handy for recovering data from a damaged CD also.

Copying CDs and DVDs

All of the major CD-creation software packages come with the option to do a direct copy of a CD or DVD disk. This is accomplished by either copying the data from the original disk in a separate drive directly to the new blank disk in the writer (on the fly copying), or more commonly, by creating a disk image on the hard drive, then using that image to create further copies on blank media.

The creation of an image file is the default method used for copying, as it is considerably more reliable and flexible. Using this method, you need only the CD or DVD writer, as the data disk can first be copied to the hard drive and then ejected to make room for the blank media.

When copying 'on the fly' you obviously need a second CD or DVD capable drive to read the data disk. When you choose to copy a disk using an image file, you can generally select whether or not you wish the image to remain on the hard drive after you create the copy, so you can use it in the future. With this method you will need sufficient hard drive space to hold the image you are (at least temporarily) creating, 700MB for CD-R/RW and up to 4.7GB For DVD media.

For copying your own data or custom music CD and DVDs, there is nothing more to it than starting the copy and inserting blank media when prompted. If you wish to make backups of commercial software or music CDs or backup your DVD collection things get much more complicated very quickly, both for logistical and legal reasons.

Much commercial software (especially games) and recent music contains forms of copy protection designed to make copying much, much more difficult. This can range from including deliberate 'imperfections' in the original CD to confuse CD writers into thinking the disk is damaged (a process introduced with the original Half-Life game) to making music CDs that actually will not play on computer CD drives to prevent copying.

DVD duplication is even more complicated, as not only are the original DVDs encrypted, they also often require editing before they will fit on a standard 4.7GB DVD-R disk.

The industries involved obviously have an interest in making it very difficult to copy their products, and this is fair enough; Software piracy is a huge problem. It does make things very tricky for the innocent user who wants to guarantee his investment in their products though. The one constant to these various methods of copy protection is this; someone has figured out how to defeat all of them at one time or another.

Newer CD writers even include support for bypassing several copy-protection methods though software, creating an interesting financial battle scenario between software companies and hardware manufacturers. While generally speaking, backing up software you have purchased for personal use is quite legal, there are several complex areas. PCstats has a comprehensive article on the various legalities involved in backing up software and music that you may wish to read.