What is the TMB file format?
A .tmb file is a thumbnail image file, but the extension is shared by several unrelated applications with no common format standard.
The most common real-world occurrence is alongside camcorder or video-editing software footage. Panasonic HD Writer and some Canon camcorders generate .tmb files as low-resolution JPEG preview images paired with .MTS video clips. These are standard JPEG data (magic bytes FF D8 FF) at small resolutions, typically 160×120 or 320×240 pixels, and may contain face-detection metadata specific to the device.
A second, historically older use came from Timbuktu Pro, a remote-desktop application published by Netopia (later Motorola). Its .tmb files were proprietary binary connection-profile records. Timbuktu Pro was discontinued around 2007 and is now obsolete.
Movie Magic Screenwriter also uses .tmb as a document backup file with an application-specific header, unrelated to either of the above.
Because the format varies by creator, there is no universal magic byte signature. To identify a .tmb file, open it in a hex editor: if it starts with FF D8 FF, it is a JPEG thumbnail and can be renamed to .jpg and opened in any image viewer. Otherwise, the file's origin - camcorder directory, legacy software folder - determines how or whether it can be opened.
Security & safety
RISK: LOWCamcorder TMB files are JPEG images - standard JPEG parser risks apply but are negligible for files from your own camera. Timbuktu Pro TMB files from unknown sources could contain connection credentials to remote hosts; discard if origin is unclear.
Format details
in a nutshell- Timbuktu Pro remote-access connection file - Discontinued remote-desktop software by Netopia (acquired by Motorola); product EOL circa 2007; these files are effectively obsolete.
- Movie Magic Screenwriter backup - Timed auto-backup of screenwriting documents created by Movie Magic Screenwriter (WriterDuet product line).
- 602PC Suite thumbnail - Thumbnail generated by 602PC Suite (Czech office suite, largely defunct).
Programs that open TMB files
Windows3 apps
IrfanView
Free Open With → IrfanView; or drag the TMB file directly - IrfanView detects JPEG content regardless of extension. 
Windows Photos / Paint
Built-in Rename the file from .tmb to .jpg, then double-click to open in Photos. Works for camcorder-originated TMB files.
Panasonic HD Writer AE
Free Used automatically when managing Panasonic camcorder footage; TMB files are read transparently as clip thumbnails. 
macOS1 app
Technical details
deep spec| Format type | No universal standard; extension reused by multiple unrelated applications |
| Dominant use case | Low-resolution JPEG thumbnail paired with camcorder footage (Panasonic HD Writer, Canon camcorders) |
| Magic bytes (JPEG variant) | FF D8 FF at offset 0 (standard JPEG header); file can be renamed .jpg and opened in any image viewer |
| Typical image dimensions | 160×120 or 320×240 pixels (camcorder preview thumbnails) |
| Color depth | 24 bpp (JPEG-based thumbnails; standard RGB color) |
| Typical file size | 2 KB - 500 KB (thumbnail images); up to several MB for document backups |
| Companion files | Panasonic/Canon .tmb files appear alongside .MTS or .MOD video clips, sharing the same base filename |
| Timbuktu Pro variant | Proprietary binary connection-profile; product discontinued ~2007; files are effectively inaccessible without the original software |
| Movie Magic Screenwriter variant | Document backup with application-specific binary header; not an image file |
| Compression | JPEG compression (camcorder variant); varies or none for other variants |
| Encoding | Binary; byte order varies by creating application |
| Associated operating systems | Windows (all variants); macOS (Timbuktu Pro, Preview-based workflows) |
| Released | Late 1990s (various independent implementations) |
TMB conversions
Community Q&A
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