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Image MIME Reference
Sigma-X3F

Sigma X3F RAW Image

image/x-sigma-x3f
VS

Windows Metafile

image/x-wmf
WMF

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

Equal browser support

Feature Support

Feature Sigma-X3F WMF
Transparency (Alpha) ✕ No Yes
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes ✕ No
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
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 →
Windows Metafile
image/x-wmf
Extension
.wmf.emf
Container Windows GDI Metafile Command Stream
Compression Uncompressed (Command Stream)
Algorithm
None
Color Depth Varies based on GDI rendering engine
Developed by Microsoft Corporation
Released 1990
Magic Bytes
D7 CD C6 9A (Aldus Placeable Metafile Header) or 01 00 09 00 (Standard WMF Header)
Full WMF reference →

Browser Support Comparison

Browser Sigma-X3F WMF
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕
✓
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
WMF

WMF Strengths

  • Infinitely scalable vector format that remains remarkably compact for simple geometric illustrations and charts
  • Historically served as a seamless conduit for copying and pasting vector graphics between disparate Windows applications via the system clipboard
Limitations
  • Notoriously plagued by historic security vulnerabilities, making raw WMF parsing a vector for exploits in legacy software
  • Completely obsolete and unsupported in modern web environments (browsers cannot render them)
  • Strictly tied to the Windows GDI architecture, making cross-platform rendering inconsistent across Linux and macOS

When to choose which format

Sigma-X3F
Use Sigma-X3F when…
  • Professional Digital Photography
  • Sigma / Foveon High-Acuity Imaging
  • Non-destructive RAW Post-Processing
WMF
Use WMF when…
  • Legacy Microsoft Office Clip Art and Icons
  • Windows GDI Graphics Export
  • Early Windows Desktop Publishing

More comparisons

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