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Image MIME Reference
Kodak-K25

Kodak K25 Raw Image

image/x-kodak-k25
VS

Sigma X3F RAW Image

image/x-sigma-x3f
Sigma-X3F

A complete technical comparison of Kodak K25 Raw Image 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 Kodak-K25 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 ✕ No Yes
Kodak K25 Raw Image
image/x-kodak-k25
Extension
.k25
Container Proprietary Kodak Raw (TIFF-based variant)
Compression Uncompressed / Proprietary Lossless
Algorithm
Proprietary Kodak Compression
Color Depth 10-bit, 12-bit (Per Channel)
Developed by Eastman Kodak Company
Released 1996
Magic Bytes
Varies (Often resembles TIFF header 49 49 2A 00 or requires proprietary parsing)
Full Kodak-K25 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 Kodak-K25 Sigma-X3F
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
Kodak-K25

Kodak-K25 Strengths

  • Historically significant format tied to the first digital camera to adopt CompactFlash memory
  • Preserves original raw sensor data, allowing modern demosaicing algorithms (via LibRaw) to extract much better image quality than 1996-era software could
Limitations
  • Completely obsolete and deeply proprietary, lacking modern raw format features found in DNG
  • Cannot be natively viewed in web browsers or standard operating system image viewers without specialized decoders
  • Subject to misidentification by automated MIME detection libraries due to structural similarities with standard TIFFs
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

Kodak-K25
Use Kodak-K25 when…
  • Vintage Digital Photography Archival
  • Kodak DC25 Camera Restorations
  • Historical Imaging Research
Sigma-X3F
Use Sigma-X3F when…
  • Professional Digital Photography
  • Sigma / Foveon High-Acuity Imaging
  • Non-destructive RAW Post-Processing

More comparisons

Kodak-K25 vs ACES → Sigma-X3F vs ACES → Kodak-K25 vs APNG → Sigma-X3F vs APNG → Kodak-K25 vs AVCI → Sigma-X3F vs AVCI → Kodak-K25 vs AVCS → Sigma-X3F vs AVCS → Kodak-K25 vs AVIF → Sigma-X3F vs AVIF → All comparisons →
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