A UD file contains a user dictionary created for OmniPage. It is an optical character recognition program. The dictionary supplements the program’s built-in dictionary. It assists in the text recognition process. The dictionary has custom words added by the user. These include proper nouns, technical terms, abbreviations. OmniPage is a powerful OCR application. It recognizes characters from images. The UD file format was developed for OmniPage. Its full name is OmniPage User Dictionary. The UD file was likely made using OmniPage. To learn more visit the manufacturer’s website.
Many file types use the UD extension. But most are not compatible. Each requires a different application. Windows links UD files to OmniPage by default. If OmniPage is removed, errors occur on UD files. Fix errors to restore PC performance. Try re-associating UD files with OmniPage. Or install a UD file converter.
Changing a file extension is risky. It alters how programs handle that file. Files have specific formats by type. Extensions identify the format. Changing it confuses programs. They may not open the file properly. It’s best to leave file extensions intact.