Convert X3F to BMP — Free Online Converter
Convert Sigma/Foveon RAW (.x3f) to Bitmap Image (.bmp) online for free. Fast, secure image conversion with no watermarks or registration....
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How to Convert
Upload your .x3f file by dragging it into the upload area or clicking to browse.
Choose your output settings. The default settings work great for most files.
Click Convert and download your .bmp file when it's ready.
About X3F to BMP Conversion
X3F is Sigma's proprietary RAW format for cameras equipped with the Foveon X3 direct image sensor — a fundamentally different technology from conventional Bayer pattern sensors. While Bayer sensors capture one color per pixel and interpolate the rest, Foveon's stacked silicon layers capture full RGB data at every pixel location, producing images with exceptional per-pixel sharpness and color accuracy. Cameras like the SD1 Merrill, DP1/DP2/DP3 Merrill, SD Quattro, and SD Quattro H produced X3F files.
Converting X3F to BMP creates uncompressed bitmap output from this unique sensor technology. BMP's simplicity ensures universal readability, preserving the Foveon's distinctive per-pixel sharpness in a format accessible to any system. X3F is notoriously difficult for third-party software to decode correctly — Sigma Photo Pro is the only official processing tool — making universal format conversion particularly important for Foveon photographers.
Why Convert X3F to BMP?
BMP is readable by every operating system and image viewer. X3F files are among the most difficult RAW formats for third-party software to decode — many RAW processors either refuse to open them or produce visibly inferior results compared to Sigma Photo Pro. Converting to BMP eliminates this compatibility barrier permanently.
The Foveon sensor's unique characteristic — full RGB capture at every pixel without Bayer interpolation — produces per-pixel sharpness that no conventional sensor can match at equivalent resolution. BMP preserves this sharpness exactly in an uncompressed format that any application can display.
Common Use Cases
- Preserve Sigma SD1 Merrill photography in universally readable BMP format
- Convert DP2 Merrill street captures to BMP for systems that cannot decode X3F
- Create uncompressed reference copies of Foveon sensor output for image quality analysis
- Deliver Sigma SD Quattro photographs to legacy systems requiring BMP input
- Archive DP3 Merrill macro photography as uncompressed bitmaps for scientific reference
How It Works
The conversion reads the X3F container and decodes the Foveon X3 sensor data. Unlike Bayer sensors, no demosaicing is needed — Foveon captures full RGB at each photosite. However, the three silicon layers have overlapping spectral responses that require complex color separation algorithms. The SD1 Merrill with its 15.3 MP (4,704 x 3,136 x 3 layers) sensor produces a BMP of approximately 44 MB at 24-bit. The Quattro architecture captures 19.6 MP luminance with 4.9 MP per-color channel.
Quality & Performance
BMP applies zero compression, preserving the Foveon sensor's unique output exactly. The per-pixel RGB sharpness — where every pixel contains real color data rather than interpolated values — is maintained without any interference. This quality is the Foveon's key advantage: medium-format-like per-pixel detail from an APS-C sensor. BMP is one of the few output formats that preserves this distinction without any lossy degradation.
Device Compatibility
| Device | X3F | BMP |
|---|---|---|
| Windows PC | Partial | Native |
| macOS | Partial | Partial |
| iPhone/iPad | Partial | Partial |
| Android | Partial | Partial |
| Linux | Partial | Partial |
| Web Browser | No | No |
Tips for Best Results
- 1Foveon sensor output has medium-format-like sharpness at APS-C size — BMP preserves this unique characteristic
- 2X3F decode quality varies dramatically between software — verify the conversion output matches your expectations
- 3For general use, PNG provides identical quality at 40-60% smaller file sizes than BMP
- 4The SD1 Merrill's true RGB capture means BMP output has no Bayer interpolation artifacts at all
- 5Archive both the original X3F and converted BMP — Sigma Photo Pro may produce superior results from the X3F
X3F to BMP preserves the Foveon sensor's unique per-pixel RGB data in the most universally readable format. Essential for maintaining access to Sigma camera output given X3F's notoriously difficult third-party decode.