Main » TERM » R ». Reimage is the process of removing all software on a computer and reinstalling everything. A reimage is necessary if your operating system becomes damaged or corrupted. You may also need to reimage if your system is plagued with spyware problems.The word reinstall is often used in place of reimage. reimage is necessary if your operating system becomes damaged or corrupted. You may also need to reimage if your system is plagued with spyware problems. The word reinstall is often used in place of reimage.