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Image MIME Reference
Olympus-ORF

Olympus Raw Format

image/x-olympus-orf
VS

Sigma X3F RAW Image

image/x-sigma-x3f
Sigma-X3F

A complete technical comparison of Olympus Raw Format and Sigma X3F RAW Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature Olympus-ORF Sigma-X3F
Transparency (Alpha) ✕ No ✕ No
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes Yes
EXIF Metadata Yes Yes
ICC Color Profile Yes Yes
Olympus Raw Format
image/x-olympus-orf
Extension
.orf
Container TIFF-based (with proprietary variants)
Compression Uncompressed / Proprietary Lossless
Algorithm
NoneOlympus Proprietary Lossless
Color Depth 12-bit (Per Channel)
Developed by Olympus Corporation (Now OM Digital Solutions)
Released 2000
Magic Bytes
49 49 52 4F (IIRO) or 4D 4D 4F 52 (MMOR) or 49 49 53 52 (IIRS)
Full Olympus-ORF reference →
Sigma X3F RAW Image
image/x-sigma-x3f
Extension
.x3f
Container Foveon Proprietary Header
Compression Uncompressed / Proprietary Lossless
Algorithm
NoneFoveon Proprietary Huffman-based
Color Depth 12-bit (Per Channel), 14-bit (Per Channel)
Developed by Foveon, Inc. / Sigma Corporation
Released 2002
Magic Bytes
46 4F 56 62
Full Sigma-X3F reference →

Browser Support Comparison

Browser Olympus-ORF Sigma-X3F
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
Olympus-ORF

Olympus-ORF Strengths

  • Retains maximum sensor data, allowing extreme recovery of highlights and shadows that would be permanently lost in a JPEG
  • White balance, sharpening, and color profiling are saved as metadata instructions, meaning they can be completely altered in post-production
  • Unique magic byte signatures make programmatic file sniffing highly reliable compared to other camera manufacturers' TIFF-spoofing headers
Limitations
  • Proprietary format means it requires constant updates to raw processing engines every time a new camera model is released
  • Produces very large file sizes (often 15MB to 30MB+ per image depending on sensor resolution)
  • Cannot be directly embedded into web pages or used in standard HTML/CSS contexts
Sigma-X3F

Sigma-X3F Strengths

  • Provides absolute per-pixel color accuracy without the interpolation artifacts or moiré patterns typical of Bayer-sensor RAW files
  • Unique 'FOVb' magic byte signature prevents accidental misidentification by standard file sniffers, unlike many TIFF-based raw formats
  • Incredible sharpness and detail resolution at the raw sensor level
Limitations
  • Decoding is extremely computationally expensive and completely proprietary, meaning third-party software often struggles to match the color science of Sigma's own (famously slow) Photo Pro application
  • Massive file sizes because it records three complete RGB channels for every single spatial pixel coordinate
  • Zero support in web browsers or standard OS image viewers

When to choose which format

Olympus-ORF
Use Olympus-ORF when…
  • Professional Digital Photography
  • Non-destructive Image Post-Processing
  • High Dynamic Range (HDR) Imaging Archival
Sigma-X3F
Use Sigma-X3F when…
  • Professional Digital Photography
  • Sigma / Foveon High-Acuity Imaging
  • Non-destructive RAW Post-Processing

More comparisons

Olympus-ORF vs ACES → Sigma-X3F vs ACES → Olympus-ORF vs APNG → Sigma-X3F vs APNG → Olympus-ORF vs AVCI → Sigma-X3F vs AVCI → Olympus-ORF vs AVCS → Sigma-X3F vs AVCS → Olympus-ORF vs AVIF → Sigma-X3F vs AVIF → All comparisons →
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