How does Win7 make a CD image file?

If you want to make a Win7 system to install a USB flash drive, you need to write the Win7 CD image file to the USB flash drive, so the Win7 CD image file is also very important. The Win7 CD image file can be downloaded from the Internet. If you cannot access the Internet, you can use the Win7 installation CD to create a Win7 CD image.
Step 1: Install UltraISO, run the software, and then put the Win7 installation CD into your computer's CD-ROM drive.
Step 2: Select “File” → “Open Disc”, then select the CD-ROM drive where the Win7 installation CD is located in “Open CD”.

Step 3: Click the "Open" button, UltraISO will read the disc data, select "Tools" → "creating a disc image file" command in the pop-up dialog box to set the output image file name and click path.

Step 4: Click "Create" button to start the production.