X3F to BMP Converter

How to Convert X3F to BMP Online

1. Upload Your X3F File: Drag and drop or click "+ Add Files" to load .x3f images from your Sigma SD or DP camera. Batch is supported — queue an entire shoot in one pass. Files stay on our servers and are not stored on a server.
2. Pick a Quality Preset: Default is High. Drop to Medium or Low when you only need a quick reference render, or push to Very High / Highest to preserve every Foveon layer's tonal detail for archival or scientific use. BMP is uncompressed, so a higher quality preset translates directly into a larger file rather than a higher compression ratio.
3. Set Image Resolution (Optional): Keep Original to match the Foveon native dimensions (e.g., 2640×1760 from an SD14, 4800×3200 from an SD1 Merrill), pick a Preset Resolution (4320p down to 144p), scale by Percentage, or enter a custom Width × Height (aspect ratio is preserved when you fill only one side). If your downstream tool needs print-ready output, this is also where you'd cap dimensions to your target DPI later in a vector workflow.
4. Convert and Download: Click Convert and grab each BMP individually or as a ZIP. No sign-up, no watermark, no email gating.

Why Convert X3F to BMP?

X3F is Sigma's proprietary Foveon RAW container — files begin with the ASCII signature FOVb and hold the three vertically-stacked Foveon X3 sensor layers (red, green, and blue captured at every photosite rather than interpolated from a Bayer mosaic). That structure is wonderful for color fidelity but useless to anything outside Sigma Photo Pro, a recent Photoshop with the Sigma plug-in, or the small handful of third-party RAW developers (Corel PaintShop Pro, CyberLink PhotoDirector, dcraw-based open source). BMP — Microsoft's Windows bitmap format, integrated into Windows GDI since the early 1990s — is the opposite: zero compression, no proprietary encoding, 24-bit BGR triplets that any Windows tool, image library, or embedded system can decode in a handful of lines of C. Converting X3F → BMP gives you a flat, universally readable pixel buffer of your rendered Foveon image.

• Feed legacy Windows applications — CAD packages, medical-imaging viewers, industrial inspection software, and many older LIMS clients still expect uncompressed BMP and refuse modern formats like HEIC or AVIF. A Foveon shot rendered out to BMP drops straight into those pipelines.
• Microcontroller and embedded display assets — TFT panel firmware on ESP32, STM32, and Arduino projects commonly ships a LoadBMP() helper but no JPEG or PNG decoder; 24-bit BMP from a sharp Foveon source is the easiest way to get high-fidelity bitmap art onto a small screen.
• Scientific imaging and machine vision — Researchers who want a lossless, demosaic-free pixel grid (Foveon's whole appeal) can render to BMP without worrying about a downstream JPEG quantizer or PNG zlib step touching the values.
• Forensic and archival hand-off — When you need to deliver an exact pixel record with no compression artefacts and no metadata-rewrite risk, uncompressed BMP is a defensible choice; the file IS the pixels.
• Game-engine textures and sprite atlases — Some older 2D engines (and a few asset pipelines that bake out to BMP before re-compressing to DXT/BC) consume BMP natively, and a high-quality Foveon source upscales cleanly.
• Wallpaper, splash screens, and OS-level art — Windows still happily accepts BMP for the boot/lock screen and certain icon contexts where it sidesteps the OS's PNG decoder.

If your end use is the web or any modern app, JPG / PNG / TIFF are nearly always the better target — start with X3F to JPG, X3F to PNG, or X3F to TIFF instead. And if the resulting BMP is too large for your destination, run it through Compress BMP afterwards.

X3F vs BMP — Format Comparison

BMP Quality Preset & Bit Depth Quick Guide

Quality preset on this converter controls how aggressively the Foveon RAW is rendered (sharpening, noise reduction, tone curve). BMP itself is lossless, so the file-size impact comes mostly from the chosen resolution and bit depth.

A 4800×3200 24-bit BMP (e.g., an SD1 Merrill render at native resolution) lands at roughly 46 MB before any optional padding — Width × Height × 3 + 54-byte header. Don't be surprised when your "small" RAW grows after conversion; that's the trade for compression-free storage.

Frequently Asked Questions

Which Sigma cameras produce X3F files?

Every Sigma DSLR and most Sigma compacts since the SD9 (2002): SD9, SD10 (2003), SD14, SD15, SD1 / SD1 Merrill (2011), the DP1, DP2, and DP3 fixed-lens compacts, the DP / dp Quattro series (2014 onward), and the SD Quattro mirrorless line (2016). Sigma had not released a new Foveon camera as of the end of the Quattro generation, but X3F files from any of those bodies all share the FOVb signature.

Will I lose the Foveon "look" by converting to BMP?

You lose the editability — once a Foveon shot is rendered to BMP, white balance, exposure, and color rendering are baked into the pixels and can't be re-developed the way they can from the RAW. The rendered image itself can still carry the Foveon advantage (per-pixel R/G/B without demosaic interpolation), so fine detail and color transitions usually look at least as clean as a Bayer JPEG from a comparable-megapixel camera. Keep the original .x3f archived if you might want to re-process later.

Why is my BMP so much larger than the X3F?

BMP stores every pixel uncompressed (3 bytes per pixel at 24-bit, plus a small header). A 4640×3480 16-megapixel Foveon image becomes roughly 48 MB as a 24-bit BMP no matter what was in the original 25–35 MB RAW. If size matters, render to PNG or TIFF instead, or send the BMP through a lossless compressor afterwards.

Does BMP work in web browsers and email?

Chrome, Firefox, Edge, and modern Safari do display BMP in an <img> tag — but it's not on the official web-image short-list (JPEG, PNG, GIF, WebP, AVIF, SVG) and Gmail / Outlook web won't preview it inline the way they preview JPEG or PNG. Use BMP for desktop and embedded workflows; convert to JPG or PNG for the web.

Can I keep my X3F's EXIF metadata (camera model, lens, exposure) in the BMP?

Mostly no. The BMP format has no standard EXIF chunk, so camera body, lens, shutter speed, aperture, ISO, and GPS data are dropped during conversion. If you need that information preserved alongside the pixels, render to TIFF (which carries EXIF) or keep a sidecar text/JSON file with the values pulled from the original .x3f.

What bit depth should I pick — 24-bit, 16-bit, or 8-bit?

Pick 24-bit unless you have a specific reason not to: it's the universal default, every consumer of BMP expects it, and you preserve full 8-bit-per-channel color. Drop to 16-bit (5-6-5 packed) only when you're feeding a small embedded LCD that natively wants that layout. Use 8-bit indexed for icons, sprites, or palette art where you've intentionally reduced to ≤256 colors. 1-bit is for masks, line art, and fax-grade monochrome.

Will this converter work on a .x3i or Sigma SD Quattro X3F file?

The converter accepts standard .x3f files. Quattro-generation X3F files (from the dp Quattro and SD Quattro line) use a different internal layer-resolution layout than the original X3 sensor — they're still .x3f extension and still parsed here, but if you ran into an old build of Adobe Camera Raw that rejects Quattro X3F, the same caveat applies to any third-party decoder. If a specific file errors out, try opening it in Sigma Photo Pro first to confirm the file isn't corrupt and re-export.

Why is dropping straight from RAW to BMP discouraged for normal photo work?

For most photo workflows — sharing online, printing through a lab, posting to social, sending in email — JPG or PNG are smaller, web-friendly, and equally lossless-enough for the use. BMP only makes sense when you specifically need an uncompressed pixel buffer for a downstream tool that doesn't accept anything else. If you're not sure that's your case, take the JPG route: Convert X3F to JPG gives a vastly smaller file that displays everywhere.

Is anything uploaded to your servers?

processing happens on our servers and files are removed after your session ends. No account is required and there are no watermarks, file-count limits, or paid tiers gating the converter.