Image MIME Reference
FLIF
Free Lossless Image Format
image/flif
VS
Image Exchange Format
image/ief
IEF
A complete technical comparison of Free Lossless Image Format and Image Exchange Format — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | FLIF | IEF |
|---|---|---|
| Transparency (Alpha) | Yes | ✕ No |
| Animation Support | Yes | ✕ No |
| Progressive Loading | Yes | ✕ No |
| HDR Support | Yes | ✕ No |
| EXIF Metadata | Yes | ✕ No |
| ICC Color Profile | Yes | ✕ No |
Free Lossless Image Format
image/flif
Extension
.flif
Container
FLIF Bitstream
Compression
Lossless (MANIAC Entropy Coding)
Algorithm
MANIAC (Meta-Adaptive Near-zero Integer Arithmetic Coding)
Color Depth
1-bit to 16-bit (Per Channel), Grayscale, RGB, RGBA, CMYK
Developed by
Jon Sneyers and Pieter Wuille (Cloudinary)
Released
2015
Magic Bytes
46 4C 49 46
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)
Browser Support Comparison
| Browser | FLIF | IEF |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
FLIF
FLIF Strengths
- Achieves some of the highest lossless compression ratios ever developed for raster images
- Incredible progressive decoding allows an image to be highly recognizable even after only 5% of the file has been downloaded
- Supports animations and complex alpha channels losslessly
Limitations
- Officially abandoned in favor of JPEG XL
- Zero native support in web browsers or standard operating system previewers
- Encoding speed can be significantly slower than standard PNG or WebP compression
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
When to choose which format
FLIF
Use FLIF when…
- Archival of Uncompressed Image Assets
- Bandwidth-Constrained Progressive Image Loading (Historical)
- Medical and Scientific Imaging Storage
IEF
Use IEF when…
- Legacy Fax Transmissions
- Early Internet Gateways
- Archival