Image MIME Reference
EDMICS-RLC
Fuji Xerox EDMICS-RLC
image/vnd.fujixerox.edmics-rlc
VS
T.38 Fax over IP (FoIP)
image/t38
T.38
A complete technical comparison of Fuji Xerox EDMICS-RLC 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 | EDMICS-RLC | T.38 |
|---|---|---|
| Transparency (Alpha) | ✕ No | ✕ No |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | ✕ No | ✕ No |
| EXIF Metadata | ✕ No | ✕ No |
| ICC Color Profile | ✕ No | ✕ No |
Fuji Xerox EDMICS-RLC
image/vnd.fujixerox.edmics-rlc
Extension
.rlc.edm
Container
Fuji Xerox EDMICS Wrapper
Compression
Run-Length Coding (RLC / RLE)
Algorithm
Run-Length Coding (RLC)
Color Depth
1-bit (Monochrome), 8-bit (Grayscale)
Developed by
Fuji Xerox Co., Ltd.
Released
1990s
Magic Bytes
Unknown (Proprietary Container)
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)
Browser Support Comparison
| Browser | EDMICS-RLC | T.38 |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
EDMICS-RLC
EDMICS-RLC Strengths
- Simple, computationally inexpensive Run-Length Coding enabled rapid compression and decompression on low-power legacy hardware
- Deeply integrated into Fuji Xerox enterprise hardware for seamless, automated scan-to-archive workflows
Limitations
- Completely proprietary and closed-source, making modern archival extraction and migration extremely difficult
- No support in modern image processing libraries like ImageMagick, libvips, or standard viewers without bespoke decoding tools
- RLC compression is far less efficient than modern algorithms like PNG (Deflate) for complex documents
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
EDMICS-RLC
Use EDMICS-RLC when…
- Fuji Xerox EDMICS Enterprise Systems
- Archival of Scanned Engineering Documents
- Legacy Corporate Scanning Pipelines
T.38
Use T.38 when…
- Fax over IP (FoIP) Transmissions
- SIP/SDP Media Negotiation
- VoIP Gateways and PBX Systems
- Enterprise Fax Servers