System image backups are used to restore an entire system. However, there is a workaround that you can use to extract individual files from a system image backup which is the subject of this article.
Restore single file from Windows System Image Backup
Step 1. Open the disk management application.
Step 2. In the disk management window, click Action -> Attach VHD.
Step 3. Click Browse and locate the system image backup file (.VHD).
Step 4. Click Open and mount the image.
Step 5. The mounted system image will appear as a drive inside your computer window.
Step 6. Browse the contents as you do in other drives and copy the files to your main drive that you like to restore.
Step 7. When you are done copying the image, detach the VHD. In disk management window, right-click the box that corresponds to the VHD and click on detach VHD.
See here for how to transfer data from or to another system.