MDI files are Microsoft Document Imaging files. This file type is most common for scanned files or for saving files within Microsoft Office that need to be printed at a time when a printer is not accessible. Similar to a PDF, an MDI file preserves document formatting better than a DOC file, although a PDF is more universally accessible. Microsoft Office is needed to open an MDI file, while a PDF can be opened with a number of free programs. Converting an MDI into a PDF is a quick and easy process.
