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Image MIME Reference
Kodak-DCR

Kodak Digital Camera Raw

image/x-kodak-dcr
VS

T.38 Fax over IP (FoIP)

image/t38
T.38

A complete technical comparison of Kodak Digital Camera Raw 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 Kodak-DCR 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
Kodak Digital Camera Raw
image/x-kodak-dcr
Extension
.dcr
Container TIFF/EP
Compression Uncompressed / Lossless JPEG
Algorithm
NoneLossless JPEG (ITU-T81)
Color Depth 12-bit (Per Channel)
Developed by Eastman Kodak Company
Released 1998
Magic Bytes
49 49 2A 00 or 4D 4D 00 2A
Full Kodak-DCR 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 Kodak-DCR T.38
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
Kodak-DCR

Kodak-DCR Strengths

  • Preserves the full dynamic range and uncompressed raw sensor data captured by foundational professional digital cameras
  • Utilizes the standard TIFF container structure, ensuring that open-source decoders like LibRaw can easily parse and interpret the files long after official vendor support has ended
Limitations
  • Completely obsolete proprietary format tied to camera hardware that is no longer manufactured
  • Shares the TIFF magic header, leading to widespread misidentification by automated MIME detection libraries
  • Cannot be natively viewed in web browsers or standard operating system image viewers without specialized codecs
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

Kodak-DCR
Use Kodak-DCR when…
  • Vintage Professional Digital Photography (Kodak DCS series)
  • Non-destructive Image Post-Processing
  • Raw Imaging Archival
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

Kodak-DCR vs ACES → T.38 vs ACES → Kodak-DCR vs APNG → T.38 vs APNG → Kodak-DCR vs AVCI → T.38 vs AVCI → Kodak-DCR vs AVCS → T.38 vs AVCS → Kodak-DCR vs AVIF → T.38 vs AVIF → All comparisons →
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