Image MIME Reference
IEF
Image Exchange Format
image/ief
VS
JPEG XS Image Sequence (HEIF Container)
image/jxss
JPEG-XS-Sequence
A complete technical comparison of Image Exchange Format and JPEG XS Image Sequence (HEIF Container) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | IEF | JPEG-XS-Sequence |
|---|---|---|
| Transparency (Alpha) | ✕ No | Yes |
| Animation Support | ✕ No | Yes |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | ✕ No | Yes |
| EXIF Metadata | ✕ No | Yes |
| ICC Color Profile | ✕ No | Yes |
Image Exchange Format
image/ief
Extension
.ief
Container
TIFF Class B (TIFF-B)
Compression
Lossless (MH, MR, MMR) / Uncompressed
Algorithm
MHMRMMRUncompressed
Color Depth
1-bit (Monochrome)
Developed by
IETF Network Fax Working Group
Released
1992
Magic Bytes
49 49 2A 00 (Little-endian) / 4D 4D 00 2A (Big-endian)
JPEG XS Image Sequence (HEIF Container)
image/jxss
Extension
.jxss.jxs
Container
HEIF / ISOBMFF (ISO/IEC 23008-12)
Compression
Lossy (Visually Lossless) / Mathematically Lossless
Algorithm
JPEG XS (ISO/IEC 21122-1)
Color Depth
8-bit, 10-bit, 12-bit, 14-bit, 16-bit
Developed by
Joint Photographic Experts Group (JPEG)
Released
2019
Magic Bytes
XX XX XX XX 66 74 79 70 6A 78 73 73
Browser Support Comparison
| Browser | IEF | JPEG-XS-Sequence |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
IEF
IEF Strengths
- Provided a standard method for exchanging bi-level fax images during the early days of the Internet
- Supported multi-page documents
- Leveraged the highly resilient and well-documented TIFF container
Limitations
- Completely obsolete and unsupported in modern computing environments
- Strictly limited to 1-bit monochrome data, lacking color or grayscale capabilities
- Magic bytes overlap completely with standard TIFF, making specific filetype detection difficult without parsing internal tags
JPEG-XS-Sequence
JPEG-XS-Sequence Strengths
- Provides sub-millisecond encoding and decoding latency across a video sequence while retaining visually lossless quality
- Leverages the robust ISOBMFF track structures for accurate frame timing, audio synchronization, and metadata handling
- Optimized for professional video production and IP broadcasting workflows
Limitations
- Zero web browser compatibility, limiting its use entirely to professional and industrial hardware workflows
- Compression ratios are significantly lower than consumer video codecs like HEVC or AV1
- Extremely niche format that requires highly specialized broadcast hardware or custom software libraries to process
When to choose which format
IEF
Use IEF when…
- Legacy Fax Transmissions
- Early Internet Gateways
- Archival
JPEG-XS-Sequence
Use JPEG-XS-Sequence when…
- Live Broadcast Video Snippets
- Medical Imaging Sequences
- HDR Burst Photography Archiving
- Automotive & Drone Video Storage