In a nutshell, a disk images is an exact, binary copy of another disk. They are like a digital photogrpah of the parent disk.

NOTE:By the way, on some pages dealing with specific type of image files I've neglected to mention that it's helpful to make file extenstions visible in Windows - by default, they are hidden. You can do this by opening any window and choosing the following from the task bar at the top: Tools > Folder Options > View. You'll see a radio button that is ticked and which says Hide extensions for known file types. Untick that button and hit "apply".

The Most Common Disk Image Formats

Far and away, the most common type of image file is the .ISO file, followed by the Bin & Cue format (a two-part image file format). The nice thing about these two formats is this: in order to render image files useful they must be burned to disk in a particlular mode or mounted, and, almost all burning software will have the ability to read and burn/convert these two formats and any sort of emualtion (mounting) type of software will function with them, as well; these formats could be described, I suppose, as sort of standards as far as image files go. They can be manipulated/burned with a lot of different programs.

As a matter of fact, .ISO files have always been supported on Unix/Linux and there is also a GNU (Unix freeware) program, now, that can read bin and cue files.

By the way: as I've mentioned above disk images must be burned to disk (using particluar settings) or "mounted" using a program that provides disk emulation. The latter sounds very technical - it is actually very simple and we'll talk about it after a brief overview of some other image file types (down the page just a bit).

Less Common (proprietary) Disk Image Formats

Okay - we've talked about .ISO files and Bin & Cue files which, as I've explained, can be manipulated (burned or mounted) by many programs; they are standards, so to speak. Of course, you can make image files from your favorite disks (which we'll talk about in a moment) and I would recommend sticking with these common formats. However, there are also some propietary disk image formats. By proprietary, I mean that you must have one, particular program installed to make any sense of these things (I don't know why anyone fools with these!). These include......

• .CIF - used by Roxio's Easy CD Creator and recognized by no other software.
• .CDI - a Disk Juggler file format, which can be burned by Alcohol 120% (a burning/emulation program) but which, again, is not recognized by anything else...
• .BWT - a BlindWrite format, but can also be burned by Alcohol 120%
• .MDS - completely proprietary to Alchohol 120%
• .DAA - completely proprietary to PowerISO
• .NRG - proprietary to Nero, but can also be burned by Alcohol 120%

Converting Image Files to Usable Data

NOTE: All of this is a bit of a rehash from my pages on .ISO files and Bin & Cue Files.

So, suppose you've got an ISO file or a Bin & Cue file set and you need to convert these strange things to a usable format. You can do one of two things:

• Burn them to disc using a raw data mode, or
• Mount them with an emulation program (daemontools is a popular, free program designed to mount image files)

Option 1: Burn to disk (and convert to standard data)

All of the above sounds a bit technical and, well, it just ain't so! First of all, as of this writing (January, 2009), almost all burning software will have an option - clearly marked - which says something like "BURN AN IMAGE FILE", or "BURN AN ISO FILE". It may be labeled somewhat differently but, take a look at your software's options and you will find something along these lines. When you burn an image file, in this mode, you are converting what is termed "raw data" to a standard, usable form. Although it's may not be abundantly clear what this does, if you've never used this mode before, you're software is saying choose this option and...

1. Insert a blank CD or DVD in a drive,
2. Choose an image file to burn, and
3. I will burn the file and, in the process, convert the raw data on the disk to the plain old files and folder that you're used to seeing; I will turn this raw data - this weird file - into a functional CD or DVD!

And, by the way, if you simply burn something like an .ISO file in a standard "BURN DATA" mode you will only end up with an equally useless copy of the ISO file on a disk - in other words, you will have the file, burned to disk, in precisely the same format as you currently have it on your Desktop (or wherever).

While I am speaking somehwhat generally, here, darned near any modern CD/DVD software will burn an .ISO file or a Bin & Cue file. If you've got Bin & Cue files you navigate, with your burning program, to the associated Cue file and select it to burn the image. Now, as I have already explained, if you have any of the most popular burning software programs you're in pretty good shape for burning .ISO or Bin & Cue files.... However, if you've got a .DAA file - or one of the less common formats - you may need to "obtain" a singular, specific program in order to decode the image file (I suggest that you buy the software, but how you get your hands on the software is your business.....).

A few programs that work well for burning common image files type are:

• Alcohol 120% - a bizarrely named little program that will burn (or mount - we'll get to that) more different type of image files than any other program.
• Nero (or AheadNero) - this come bundled with new harware, therefore damned near everyone has a copy...
• Ashampoo - this is a really simple program that doesn't have nearly as many features/options as Nero but which is a great little disk burning suite.
• Probably a bunch of others - there are a lot of programs that will burn/convert these two formats. As far as what they are, that's why God made Google......

Regarding the less common, or proprietary image types

If you happen to download one of the less common image file type that I mentioned at the top of this page - as I've said - your options are often greatly reduced and you may be in something of a pickle. For instance, not long ago I downloaded a file that was in the .DAA format. I had a version of PowerISO that was about a year old. To my amazement, it wouldn't recognize the file which was in it's own, patented, proprietary format (only the brand new version of PowerISO would work!). If you download a file in one of these "goofy" formats - as I stated in the previous paragraph - you're going to have either buy or download a copy of the associated program to do anything with them.

Later on, on this page, I'll briefly describe how you go about making a disk image. People typically make such images to have backups of favorites disks, for themselves, or to give to friends. As I've mentioned at the top of this page, if you make an image file from a disk I would suggest making an .ISO file or a Bin & Cue file (for reasons which should be obvious based upon what I've explained).

Option 2: Mount the image file

Ahh - mounting the image file.... sounds almost scientific - very technical.. Actually, it's really simple. There are a number of programs which provide CD/DVDrom emulation and work in conjunction with image files. One such free program is called Daemontools and I've written a brief page, here, with some pics which show you how it works.

Let's take Daemontools for example and simply explain how you'd use it with an image file:

• Download the program Daemontools (it's free!)
• Install the program - it install in about 5 seconds....
• After it's installed you can go to My Computer and you'll notice that it looks as if you've installed a new hardware DVD drive....(called a "virtual drive" - because it's virtual, not a real piece of hardware)
• Daemontools places a red ligntning bolt icon on your taskbar - go there, and from the menu, navigate to an image file
• Choose the image file and choose "mount image file"
• The computer will respond as if you've put an actual CD/DVD in a regular drive - in other words, a program will start installing...or whatever! If it's an .ISO file that's a music CD, it will play music - again, it's just as if you'd burned the image, in a conversion mode, and placed the new CD or DVD in a regular disk drive...

Why Mounting an Image File Is Useful

There are a number of advantages, depending upon your situation, to mounting an image file as opposed to burning/converting the file. For one thing, if you've downloaded something and don't know if it's really anything you'd ever find useful you can try out a program without even wasting one blank CD or DVD. If it isn't anything you'd ever want, you can simply umount the file and deltete the image file - and, hey, that's one less burn cycle you've eaten up with your CD or DVD burner, too! And yet another advantage: let's say the image file is a music CD or a movie. To play these sorts of things your optical drives have to spin constantly; it's hard on the drives and the performance is not nearly as good as it would be if your computer were reading the data from the mounted disk image (straight from your hard drive).

A final advantage which I really like: I run a small computer repair business and create a shared folder on my network in which I keep image files. When I've just reformatted a computer and need to install a bunch of standard software (office suites, etc.) I really don't want to have to walk around with a stack of disks. So, I install deamontools and navigate to the shared folder on my network that contains the image files. Again, a lot less wear and tear on optical drives and I'm not stumbling around with a stack of CDs/DVDs, potentially sratching them up, etc.

Creating Image File Backups

This section is going to be pretty brief. To create an image file you will need one of numerous programs which will read a CD or DVD and create an image file - this, I suppose, would be pretty obvious. They all operate pretty similarly. You install the program, place a disk in your optical drive, and find the menu that says something like "Create a disk image?". Some programs will let you create the image file and save it in any one of a variety of formats - others will only save the image in a particular format. My favorite prgram for creating image files is UltraISO. Anyway, here's a non-comprehensive list of some popular programs for creating image files from disks:

• UltraISO
• MagicISO
• WinISO
• PowerISO (not recommended)

By the way, if you happen to want to create a disk image of a file that was originally burned as a multi-session disk (burned once, then burned again adding data) these must be saved in the bin & cue format - they cannot be saved in any other format.