An ISO image is an archive file of an optical disc that contains the data contents of every written sector of an optical disc, including the optical disc file system. ISO images can be created from optical discs or from a collection of files by image creation software.
The contents of a downloaded ISO file can be accessed only by writing it to a CD/DVD disk. Now we have found two way to so that you can access contents of ISO images file without writing to optical media. 
First Way
A utility called ISO Opener allows you to extract all the content of an ISO file on your hard drive.
Download this  utility from here and install it on your system. When you will launch the application you will see a window opening in front of you similar to the screenshot above. Select the ISO file that you want to extract by clicking on “open” button and specify the output folder where you want to extract the iso, and after all that click on Extract Button as per screenshot above.
It is a freeware, so there is no issue. Its easy to use also.It works on all versions of windows including Windows 8
Second Way
Today everybody know the name of a good software called Winrar.
I hope you may have already installed this software, if not then just download it from here. It comes with 40 days trial period. But, its benefit is that after getting expired also there is no issue. It will work fine after trial period also. Every time when you will use it a popup window will open like below screenshot.
Just click on “Close” button and proceed for further steps.

Now coming to the topic. 

Just open the winrar software after installing it. Now go to options from menu and click here settings… Here go to Integration tab and here you will find one box labeled with ISO. Just tick it and you have done it. Now all your image file which is available in your hard disk can be extracted as a normal zip file.