Hi,
Yes, you can perform an in-place upgrade with the ISO mounted.
But make always full system image or a backup of all your important data!
1. Run
Setup.exe from the ISO, and click the
Install now button.
2. In the next screen select the option: "Go online to install updates now (recommeded).
3. Select the right version (with GUI) and click
Next.
4. Next, accept the license terms and click
Next.
5. In the next Window, select the option:
Upgrade: Install Windows and keep files, settings and applications.
6. The installation process will perform a compatibity check, please read this part carefully.
7. If you agree with the changes, click
Next.
8. Follow the further intructions to complete the in-place-upgrade.