What is X3F, and why this page?

X3F is a file format for Sigma cameras, containing Foveon based images. I assume, as you are here, that this makes perfectly sense to you :)

The reason for this page is that I (Roland) am interested in the Foveon technology and that I have written some software to read X3F files. It all started by me reading news in rec.photo.digital in 2001 or so. And then later reading the Sigma SLR forum at DPReview.

Open Source

We have chosen to make these tools open source, under an BSD lookalike license. The sorce code can be found at github: GITHUB. The executables for Linux, OS-X and Windows can be found here: x3f.tgz (build 041). If you run Windows and rather would like to download a zip file, take this instead: x3f.zip


No installation. Executables can be found in the three directories bin/linux, bin/osx and bin/windows in the downloaded file.

The info tool

This is really a test program - doing nothing of any great value. It shows how to use the X3F IO library for reading and writing X3F files. It also dumps some information about the file. It is used thus:

x3f_io_test foo.x3f

The extract tool

This tool can extract the RAW Foveon sensor data and dump it as TIFF (or RAW). By default the data is not scaled or gamma coded. It can also dump the JPEG (thumbnail) file. It can be used thus:

x3f_extract -tiff foo.x3f
x3f_extract foo.x3f

x3f_extract -jpg foo.x3f

The first will create a file called foo.x3f.tif from the RAW data and the second a file called foo.x3f.jpg from the embedded JPEG thumbnail. The x3f_extract tool can take several input files, i.e. work in batch mode. There are also more ways of using it. This can be found at GITHUB in the file doc/readme.txt.

The Foveon RAW format

The Foveon/Sigma RAW format is a false color three channel image. The x3f_extract tool cannot (currently) convert to real RGB colors. Thats the aim though. We will see.

SD1 RAW extraction is now supported

The new in this version is that all Sigma cameras now are supported. Both the older ones SD9-SD14, DPx and SD15. But now also SD1 and the old Polaroid camera.

The Format(s)

I plan to write som documents describing the formats. Some info can be found here and there on the net - but if you have not implemented the code you cannot get a full picture of the formats used. We will see - sometimes such plans never materializes.

Support OpenRAW

We believe that the format of a file that is produced by your camera shall be known to you, the photographer. It is your digital negative and you shall be able to use it. E.g., if you are a programmer you shall be able to write your own software handling it or you shall be able to benefit from commercial or free third party software.

Therefore we support the OpenRAW initiative. Unfortunately, the initiative is currently sleeping. The more reason to care!

OpenRAW lgo