PowerISO is a CD and DVD burning tool that can also mount disk images in virtual drives to allow them to be used just like a physical disc. PowerISO cannot create IMG files directly, but IMG files -- a type of disc image, which in turn is a virtual copy of a physical disc -- are essentially ISO files with a different extension. You can create an IMG file with PowerISO by creating an ISO file, then changing the extension in Windows Explorer.
Click the "Add" button and select all the files you wish to add to the ISO/IMG file.
Click "File" and select "Save As." Choose "ISO" as the file type, then click the "Save" button. PowerISO will save the ISO to your hard drive.
Launch Windows Explorer and select the "Tools" menu followed by "Folder Options."
Click the "View" tab and deselect the "Hide Extensions for Known File Types" option. Click "OK" to return to the Explorer window.
Navigate to where you saved your ISO file, then right-click the file and select "Rename."
Erase the ".iso" extension at the end of the file name and type in ".img" instead. Press "Enter" to save the file as an IMG file.