Image MIME Reference
FLIF
Free Lossless Image Format
image/flif
VS
RealNetworks RealFlash
image/vnd.rn-realflash
RealFlash
A complete technical comparison of Free Lossless Image Format and RealNetworks RealFlash — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | FLIF | RealFlash |
|---|---|---|
| Transparency (Alpha) | Yes | Yes |
| Animation Support | Yes | Yes |
| Progressive Loading | Yes | Yes |
| 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
RealNetworks RealFlash
image/vnd.rn-realflash
Extension
Container
RealMedia / SWF
Compression
Vector (Flash) / RealAudio Compression
Algorithm
Macromedia Vector CompressionDeflate (Zlib)
Color Depth
8-bit, 24-bit, 32-bit
Developed by
RealNetworks & Macromedia
Released
1997
Magic Bytes
46 57 53 (FWS - Standard Flash) or 2E 52 4D 46 (.RMF - RealMedia Container)
Browser Support Comparison
| Browser | FLIF | RealFlash |
|---|---|---|
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
RealFlash
RealFlash Strengths
- Allowed complex, interactive vector animations to stream smoothly over 28.8k dial-up modems
- Perfectly synchronized streaming audio with timeline-based animations, which was revolutionary in 1997
Limitations
- Heavily reliant on proprietary browser plugins (RealPlayer), which were notoriously bloated
- Completely obsolete and unsupported on the modern web
- Tightly coupled server-client architecture required expensive RealServer licenses to host
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
RealFlash
Use RealFlash when…
- Historical Dial-up Web Animation
- Late-1990s Interactive Music Videos
- Streaming Vector Graphics