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What is a .rtn file?
A .rtn file is a RED Thumbnail File. This one is a specialist format without an obvious everyday home.
How to open a .rtn file
- The program that created it is by far the most reliable way to open it.
- On Windows, use a hex viewer or the free TrID tool to identify what the file really is.
- On Mac or Linux, running `file yourfile` in the terminal identifies most formats instantly.
The registry records this extension against RED Thumbnail File, so software from that family is the most likely match.
How to convert a .rtn file
- Identify the file first, then look for an export or Save As option in whatever program can read it.
The technical record
For archivists, developers and the merely curious: these are the PRONOM registry entries for .rtn.
| Format name | Version | MIME type | PUID |
|---|---|---|---|
| RED Thumbnail File | — | — | fmt/1664 |