X3F File

What are X3F files and how to open them

Are you having problems opening an X3F file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your X3F files.

What is an X3F file?

An .X3F file is a Sigma Foveon X3 Raw Picture file.

The Sigma Foveon X3 Raw Picture File is a proprietary raw image format used by Sigma cameras fitted with Foveon X3 sensors. It stores exactly what the camera's sensor captures, without in-camera processing like color interpolation, sharpening, or compression beyond lossless. Because every pixel location records full red, green, and blue layers, X3F files offer greater color fidelity and detail than formats that use Bayer filters.

These files are created when Sigma cameras like the SD and DP series are set to record in RAW or X3F mode. After a photo is taken, the unprocessed sensor data plus metadata such as shutter speed, aperture, ISO, white balance, and other settings are saved in the X3F container. Later, a photographer typically uses dedicated raw-processing software to develop the image - adjusting exposure, color, noise reduction - then exporting to a more common format like TIFF or JPEG once satisfied.

Sigma itself uses lossless compression inside the X3F files, with data precision often at 12 bits per color channel. The files also support embedded previews or thumbnails and full metadata, including Exif tags.

Internally, every X3F file begins with the four ASCII characters FOVb (hex: 46 4F 56 62) at offset zero.

How to open X3F files

We have identified four X3F openers that are compatible with this specific type of X3F file.

Programs that open Sigma Foveon X3 Raw Picture files

Last updated: January 22, 2025

Various apps that use files with this extension

These apps are known to open certain types of X3F files. Remember, different programs may use X3F files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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