Free tool · RAW preview · Runs in your browser
Convert X3F to JPG
Short answer
Choose your X3F files and the tool saves the full-size JPEG that the camera stored inside each one, in your browser with no upload. It does not develop the sensor data.
Nothing is uploaded. The tool takes the full-size JPEG preview that the camera stored inside the RAW file; it does not develop the sensor data.
Key takeaways
- All 2 X3F files we tested held a JPEG preview (2 files from 2 camera models).
- The preview is 4.6 MP to 14.8 MP: Sigma DP1 gave 4.6 MP, Sigma DP1 Merrill gave 14.8 MP.
- Small: the preview was 11.4% to 19.1% of the RAW file's size, so the JPG is far smaller than the file you started with.
- Estimated JPEG quality of the previews: 95 to 98 on the 1 to 100 scale. Cameras use their own tables, so this is an equivalent, not a setting you can change.
- It is quick: finding the preview took 18 to 87 ms per file in our run, and 37 to 122 ms in a browser for the largest files (43 MB to 64 MB).
- It is the camera's own rendering (white balance, style and sharpening already applied), not your RAW data; you cannot recover shadows or highlights from it.
Measured: what is inside the X3F files
All 2 X3F files we tested held a preview, 4.6 MP to 14.8 MP. Every extracted JPEG opened in ffmpeg without errors.
Measured with the tool's own code (the same functions the page runs) on 79 camera RAW files from the CC0 sample collection at raw.pixls.us: 27 file types from 28 makers, from compact cameras to medium format. Every JPEG the tool extracted was then read by ffprobe and decoded end to end by ffmpeg; the size, quality and sensor figures come from the files themselves.
| Camera | RAW file | JPEGs found inside | Used | Valid |
|---|---|---|---|---|
| Sigma DP1 | 10 MB | 2640 × 1760, 221 × 147 | 2640 × 1760 | Yes |
| Sigma DP1 Merrill | 53 MB | 4704 × 3136, 221 × 147 | 4704 × 3136 | Yes |
In all 2 files the preview was a complete, valid JPEG; ffmpeg decoded each one without an error.
Measured: how big the preview is
| Camera | Preview size | Preview megapixels | Share of the sensor image | Estimated JPEG quality | Preview as share of RAW file |
|---|---|---|---|---|---|
| Sigma DP1 | 1.2 MB | 4.6 MP | not in the file header | 95 | 11.4% |
| Sigma DP1 Merrill | 10 MB | 14.8 MP | not in the file header | 98 | 19.1% |
The smallest preview was 4.6 MP (Sigma DP1); the largest was 14.8 MP (Sigma DP1 Merrill). A preview with fewer pixels than the sensor is fine for sharing and proofing, but it will print smaller and crop worse than a developed RAW.
What you get: the camera's picture, not your RAW data
The preview is what the camera rendered at the moment of shooting: its white balance, its picture style, its sharpening, in 8 bits per channel. Wikipedia notes that processing from the sensor to a viewable image involves operations such as demosaicing, color translation and compression, and that a RAW developer lets you change them afterward; the preview has them baked in.
That makes it a good proof and a good file to share quickly, and a poor starting point for rescuing a dark or blown-out frame. If you need that, develop the RAW file in a RAW editor.
About X3F and the Foveon sensor
Sigma cameras with a Foveon X3 sensor capture red, green and blue at every pixel instead of one color per pixel; Wikipedia notes that such RGB raw data still needs processing but needs no demosaicing. The two X3F files we tested held full-size JPEG previews, one of them 4704 × 3136 pixels.
Rotation
Phones and cameras record which way they were held in the RAW file, and some previews do not carry that flag. In our samples the tool copied a rotation flag from the RAW container into the JPEG for 1 file so the picture shows upright.
When there is no preview
27 of our 79 files held no JPEG the tool could use: DCR, DNG, 3FR, IIQ, GPR, CRW, ERF, RAW, FFF, MRW, MEF among them. The tool says so instead of guessing. In those files the only picture is the sensor data, and a RAW developer is needed.
The tool saves the largest valid JPEG in the file and lists the others. In a few old compact-camera files that is only a thumbnail, and the table on this page shows its size so you can see when that happens.
Free tools:RAW to JPG for all camera typesHEIC to JPGCompress an imageRemove EXIF data
How the preview is found
Most RAW formats are built on the TIFF layout, and others (Canon CR3, Fujifilm RAF, Sigma X3F) have their own. Rather than rely on each maker's tags, the tool walks the file looking for the start of a JPEG and then reads that JPEG segment by segment until its end marker, so a stray byte pair inside compressed data is not mistaken for an image. It keeps baseline and progressive JPEGs and skips the lossless JPEG streams that hold the sensor data themselves.
It then picks the largest picture, lists the others, and saves it unchanged. Scanning took 37 to 122 ms in a browser for files of 43 MB to 64 MB.
How the numbers were measured
The tool's own scanning code ran on 79 CC0 files; the script, the list of files and the full results are saved with the page's evidence. For each file we recorded every JPEG found, the one used, its estimated quality (from the luminance quantization table, compared with the standard table), and the sensor image size where the file states it. Each extracted JPEG was read by ffprobe and decoded by ffmpeg to the end: 52 of 52 passed.
Questions people ask
How do I convert X3F to JPG?
Choose the file above. If it holds a JPEG preview, the tool saves it as a JPG. It works in your browser; nothing is uploaded.
Is my file uploaded?
No. The file is read and the JPEG is taken out in your browser.
Is this the same as developing the RAW file?
No. It saves the picture the camera already rendered. Developing reads the sensor data and lets you change white balance, exposure and more; that needs a RAW editor.
Why is the picture smaller than my camera's resolution?
Many cameras store a smaller preview than the sensor image. In our test 15 of 34 previews with a known sensor size had under 90% of its pixels.
Does it lose quality?
The JPEG is saved exactly as the camera stored it, without being compressed again. The only quality limit is the camera's own preview.
Can I convert many files at once?
Yes. Choose several files; download each one or a ZIP.
Does it keep the date and camera settings?
Whatever the camera stored in the preview's Exif is kept. Use the EXIF remover if you want it gone.
How big is the file I get?
In our test the preview was 11.4% to 19.1% of the RAW file's size (1.2 MB to 10 MB).
Why not just open the RAW file in my photo app?
You can, and a RAW editor gives you more control. This tool is for when you need a JPG quickly, on a device without that software.
Related
Sources and how we checked
- Wikipedia: Raw image format (read 2026-10-10)
- Wikipedia: Foveon X3 sensor (read 2026-10-10)
- raw.pixls.us: RAW sample database (CC0) (read 2026-10-10)
- FFmpeg Documentation: ffprobe (used to check every extracted JPEG) (read 2026-10-10)
Reviewed October 10, 2026. The measurements ran the tool's own code on 79 camera RAW files from the CC0 collection at raw.pixls.us and decoded every extracted JPEG with ffmpeg. The files and results are in data/seo/hub/evidence/2026-10-10/raw.