X3F to FAX Converter

Online X3F to FAX — instant results

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Privacy Protected

Convertio deletes X3F uploads right after processing. Converted FAX results are purged within 24 hours — your photos stay private.

Cloud-Based Engine

Conversion runs entirely on cloud servers — your computer stays fast and responsive even when processing large X3F files.

RAW Data Extraction

X3F contains full sensor data from Sigma cameras — the converter extracts maximum quality when producing FAX output.

How to convert X3F to FAX

1

Select files from Computer, Google Drive, Dropbox, URL or by dragging it on the page.

2

Choose fax or any other format you need as a result (more than 200 formats supported)

3

Let the file convert and you can download your fax file right afterwards

About formats

X3F is the proprietary RAW image format used by Sigma cameras equipped with Foveon X3 direct image sensors, introduced in 2002 with the Sigma SD9 — the first digital SLR camera to use a sensor that captures full color information at every pixel location. Unlike conventional cameras that use a Bayer color filter array (where each pixel records only one color and the other two are interpolated), the Foveon X3 sensor stacks three photodiode layers at each pixel site, exploiting silicon's wavelength-dependent absorption depth to capture blue, green, and red light simultaneously. X3F files therefore store a fundamentally different kind of raw data: three complete color planes captured at the same spatial location, with no demosaicing required. The format uses a proprietary container with multiple data sections including the raw sensor data (compressed using a Huffman-based scheme), embedded JPEG previews, camera metadata, and Sigma-specific processing parameters. One advantage is the absence of demosaicing artifacts: because every pixel records all three colors natively, X3F images exhibit a per-pixel sharpness and color accuracy that Bayer-based sensors achieve only after interpolation — there is no moire, no false color, and no loss of spatial resolution from the color reconstruction step. This produces a rendering quality that many photographers describe as uniquely three-dimensional and film-like, particularly at low ISO settings. X3F files can be processed using Sigma's Photo Pro software, and are also supported by dcraw, Iridient Developer, and other RAW converters.
Developer: Sigma / Foveon
Initial release: 2002
FAX is a generic image file extension associated with facsimile transmission formats standardized by the ITU-T (formerly CCITT), with the underlying Group 3 compression standard ratified in 1980. FAX files typically contain monochrome (1-bit, black and white) image data compressed using the Modified Huffman (MH) encoding defined in ITU-T Recommendation T.4, which assigns variable-length codes to run lengths of consecutive white or black pixels along each scanline. The standard resolution for Group 3 fax is 204x98 dpi (normal mode) or 204x196 dpi (fine mode), reflecting the capabilities of thermal and laser fax machines of the era. FAX files encountered digitally are often raw Group 3 encoded bitstreams or TIFF wrappers with CCITT Group 3 compression (TIFF compression tag 3). The Group 3 encoding scheme is highly efficient for typical business documents — pages with mostly white space and black text — achieving compression ratios of 10:1 to 20:1 compared to uncompressed bitmaps. One advantage is universal fax system compatibility: Group 3 encoding is the mandatory baseline for all fax machines worldwide, meaning FAX files contain data in exactly the format transmitted over telephone lines, preserving the original fax data without transcoding losses. The format's role in business communications history provides another dimension — billions of fax transmissions using this encoding moved legal documents, medical records, and business correspondence for decades, and archived FAX files represent an important documentary record. FAX images can be viewed and converted using LibreOffice, ImageMagick, GIMP, and standard document management systems.
Developer: ITU-T
Initial release: 1980

Frequently Asked Questions

Why convert X3F to FAX?

X3F files from Sigma cameras have extraordinary color depth but almost zero third-party support — converting to FAX is essential.

What opens FAX files?

FAX files can be opened with IrfanView, XnView, ImageMagick, and fax processing software.

How fast is X3F to FAX conversion?

Conversion typically completes within seconds. Processing happens on cloud servers, so your device stays responsive.

Can I convert multiple X3F files to FAX at once?

Yes — upload several X3F files simultaneously and each converts to FAX independently for individual download.

Is my data secure when converting X3F to FAX?

Your privacy is protected — uploaded files are deleted right after processing, and results are purged within 24 hours.