Free webp to jpg
EN
Image MIME Reference
Fuji-RAF

Fujifilm RAW Image

image/x-fuji-raf
VS

T.38 Fax over IP (FoIP)

image/t38
T.38

A complete technical comparison of Fujifilm RAW Image and T.38 Fax over IP (FoIP) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature Fuji-RAF T.38
Transparency (Alpha) ✕ No ✕ No
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes ✕ No
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
Fujifilm RAW Image
image/x-fuji-raf
Extension
.raf
Container Proprietary RAF Container
Compression Uncompressed / Lossless Compressed / Lossy Compressed (Modern firmware)
Algorithm
NoneProprietary LosslessProprietary Lossy
Color Depth 14-bit (Per Channel - X-Series), 16-bit (Per Channel - GFX Series)
Developed by Fujifilm Corporation
Released 2000
Magic Bytes
46 55 4A 49 46 49 4C 4D 43 43 44 2D 52 41 57 20
Full Fuji-RAF reference →
T.38 Fax over IP (FoIP)
image/t38
Extension
.t38
Container UDPTL or TCP (Network Transport)
Compression Lossless (MH, MR, MMR / T.4, T.6)
Algorithm
MH (Modified Huffman)MR (Modified Read)MMR (Modified Modified Read)
Color Depth 1-bit (Monochrome B&W)
Developed by ITU-T (International Telecommunication Union)
Released 1998
Magic Bytes
None (Network Stream)
Full T.38 reference →

Browser Support Comparison

Browser Fuji-RAF T.38
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
Fuji-RAF

Fuji-RAF Strengths

  • Retains absolute maximum sensor data, enabling massive shadow recovery and highlight protection compared to compressed in-camera JPEGs
  • Stores proprietary Fujifilm Film Simulation metadata (like Classic Chrome or Acros), allowing editors to perfectly replicate in-camera aesthetics
  • Very distinct and reliable magic header makes programmatic file detection foolproof
Limitations
  • Proprietary format requires continuous updates to third-party software (like Lightroom) whenever Fujifilm releases a new camera
  • The X-Trans sensor matrix requires highly specialized demosaicing algorithms that are extremely computationally expensive, leading to slower import and rendering times
  • Completely unsupported in standard web browsers and basic operating system image viewers
T.38

T.38 Strengths

  • Designed specifically to overcome the timing and packet-loss issues that plague traditional fax over standard VoIP audio codecs (like G.711)
  • Reduces bandwidth requirements by transmitting fax protocol data rather than uncompressed audio tones
  • Universally supported by enterprise SIP trunks and Session Border Controllers (SBCs) for FoIP
Limitations
  • Not an actual image file format, causing confusion due to its 'image/' MIME classification
  • Extremely complex to implement correctly over lossy UDP networks (relies on UDPTL redundancy mechanisms)
  • Zero support in web browsers or standard image viewing software

When to choose which format

Fuji-RAF
Use Fuji-RAF when…
  • Professional Digital Photography
  • Fujifilm X-Trans Sensor Image Archival
  • High Dynamic Range (HDR) Post-Processing
T.38
Use T.38 when…
  • Fax over IP (FoIP) Transmissions
  • SIP/SDP Media Negotiation
  • VoIP Gateways and PBX Systems
  • Enterprise Fax Servers

More comparisons

Fuji-RAF vs ACES → T.38 vs ACES → Fuji-RAF vs APNG → T.38 vs APNG → Fuji-RAF vs AVCI → T.38 vs AVCI → Fuji-RAF vs AVCS → T.38 vs AVCS → Fuji-RAF vs AVIF → T.38 vs AVIF → All comparisons →
Share this comparison