Reference

X3F (Sigma RAW)

X3F is Sigma’s RAW image format, used by Sigma cameras with Foveon sensors to store unprocessed sensor data. Files are large and need Sigma’s own software — most other editors and converters cannot open X3F directly without it.

Files & formatsGeneral

X3F (Sigma RAW)

Also known as: Sigma RAW, Foveon RAW, X3F file, how to open X3F

Sigma RAW format from Foveon-sensor cameras
Least universally supported RAW; needs Sigma Photo Pro
Export to DNG or JPEG to open it elsewhere

What an X3F file is

X3F is the proprietary RAW format Sigma cameras built around the Foveon sensor produce when shooting RAW. It stores the raw sensor readings, an embedded preview, and EXIF metadata, keeping exposure and color fully editable after capture.

The Foveon sensor captures color differently from a normal RAW sensor, which is part of why X3F is one of the least universally supported RAW formats — and, like any RAW, the files are much larger than a JPEG of the same shot.

How to open and convert X3F

X3F is best opened in Sigma’s own Photo Pro (SPP) software, which is designed for the Foveon data. Support in Adobe Lightroom/Camera Raw and third-party editors is limited and varies by camera, so the maker’s app is the reliable choice.

To use X3F more widely, export from Sigma Photo Pro to JPEG for sharing, or to DNG to move the RAW data into a container other editors understand. Keep the original X3F only while you still plan to re-edit it.

Related terms

Keep reading the reference.

Files & formatsCamera RAW (CR2, NEF, ARW)Camera RAW is the umbrella for manufacturer-specific files that store unprocessed data straight off the camera sensor — Canon CR2/CR3, Nikon NEF, Sony ARW, and others. They keep maximum editing flexibility, which makes them far larger than the JPEG or HEIC the same shot would produce.General Files & formatsDNG (digital negative)DNG (Digital Negative) is an open raw image format created by Adobe. Like other raw files, it stores the unprocessed sensor data from a camera for maximum editing flexibility — and like all raw files, it takes far more storage than a JPEG or HEIC.GeneraliOS Files & formatsRAW imageA RAW image is the unprocessed data straight from a camera sensor, before any in-camera compression or color processing. It preserves maximum editing flexibility but produces very large files — many times bigger than a JPEG or HEIC of the same shot.GeneraliOS Files & formatsJPEGJPEG (.jpg) is the most widely supported photo format. It uses lossy compression to shrink photographs dramatically, trading a small amount of detail for much smaller files. It has no transparency and is larger than newer formats like HEIC or WebP at the same quality.General

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