X3F File Format (.x3f)
An X3F file stores raw sensor data from a Sigma camera built around a Foveon X3 sensor, which captures red, green and blue at every pixel by stacking three photodiode layers in silicon rather than using the single-color-per-pixel Bayer filter nearly every other camera sensor uses.
X3F at a glance#
| Full name | Sigma Camera RAW Picture File |
|---|---|
| File extension | .x3f |
| Category | Image Files |
| Developer | Sigma |
| First released | 2002 |
| MIME types | image/x-sigma-x3f |
| Compression | Lossless |
| FileFlip support | FileFlip does not handle this format |
What a .x3f file can hold#
These are the things a X3F file either supports or does not, and they are what decides whether a conversion keeps everything or quietly drops something.
| Lossless compression | Yes |
|---|---|
| Embedded metadata | Yes |
| Colour profiles | Yes |
Strengths and limitations of X3F#
What X3F does well
- Captures full red, green and blue values at every pixel location instead of interpolating color from neighboring pixels, avoiding the moire and color-fringing artifacts Bayer-sensor demosaicing can produce
- No anti-aliasing filter is needed over the sensor, which keeps fine detail sharper
- Stores Sigma's full maker-note metadata for later reprocessing in Sigma Photo Pro
Where X3F falls short
- Only Sigma Photo Pro and a handful of raw converters with Foveon-specific decoding read it correctly; generic raw readers can produce poor results
- Sigma discontinued every camera line that shot X3F: the SD, DP and sd Quattro series had all been discontinued by 2022
- Foveon sensors historically fell behind Bayer sensors of the same era at high ISO
There's no current camera to shoot new X3F files on. The format only matters now for reprocessing existing Sigma Foveon archives.
Convert X3F to DNG or TIFF after editing in Sigma Photo Pro, since almost no software outside Sigma's own tools and a few open-source raw converters reads X3F reliably.
How to open a .x3f file#
A .x3f file opens in the programs below, grouped by the platform you are on.
| Platform | Programs that open it |
|---|---|
| Windows | Sigma Photo Pro, RawTherapee, darktable |
| macOS | Sigma Photo Pro, RawTherapee, darktable |
| Linux | RawTherapee, darktable |
| Web | FileFlip |
X3F questions people ask#
Why is X3F different from other camera raw formats?
X3F comes from Sigma's Foveon X3 sensor, which stacks three photodiode layers at every pixel location instead of the single-color Bayer filter grid nearly every other camera uses. That means each pixel in an X3F file already has full red, green and blue data rather than needing color interpolated from its neighbors.
What camera shot my X3F file?
X3F comes from a Sigma camera built around a Foveon X3 sensor, including the SD9, SD10, SD14, SD15 and SD1, the DP and dp Quattro compacts, and the sd Quattro and Quattro H, produced between 2002 and Sigma's discontinuation of the line by 2022.
Does Lightroom or Photoshop open X3F?
Support varies by Adobe version and camera generation, so Sigma Photo Pro remains the safest way to decode a Foveon file correctly, particularly for the newer Quattro-sensor cameras.
Is Sigma still making Foveon-sensor cameras?
No current Sigma camera uses a Foveon X3 sensor. Sigma discontinued the last of its Foveon-sensor DP-series compacts in 2022, and a new full-frame Foveon sensor it has been developing since had to restart from scratch in 2021 after a design flaw and was still in prototype testing as of early 2026.
Converting X3F files#
FileFlip cannot open a .x3f file, so there is nothing to convert it into here. It appears on the site as something other formats can be converted to.
FileFlip does not write .x3f files, so nothing on the site converts into this format. It works as a source only.
Every conversion runs inside your browser. The file is read from your disk, the work happens on your own machine, and nothing is uploaded. How FileFlip works names the engine behind each family and how to verify that for yourself.