Image MIME Reference
DjVu
DjVu Document
image/vnd.djvu
VS
FAST Search & Transfer Image
image/vnd.fst
FST-Image
A complete technical comparison of DjVu Document and FAST Search & Transfer Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | DjVu | FST-Image |
|---|---|---|
| Transparency (Alpha) | Yes | ✕ No |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | Yes | ✕ No |
| HDR Support | ✕ No | ✕ No |
| EXIF Metadata | ✕ No | ✕ No |
| ICC Color Profile | ✕ No | ✕ No |
DjVu Document
image/vnd.djvu
Extension
.djvu.djv
Container
Interchange File Format (IFF)
Compression
JB2 (Bi-tonal Text) / IW44 (Wavelet Background) / BZZ (General Data/Text)
Algorithm
JB2IW44BZZ
Color Depth
1-bit (Foreground Text), 24-bit (Background)
Developed by
AT&T Labs (Yann LeCun, Léon Bottou, Patrick Haffner, Paul G. Howard)
Released
1996
Magic Bytes
41 54 26 54 46 4F 52 4D
FAST Search & Transfer Image
image/vnd.fst
Extension
.fst
Container
Proprietary FAST Container
Compression
Proprietary
Algorithm
Unknown (Proprietary FAST encoding)
Color Depth
Unknown
Developed by
FAST Search & Transfer ASA (Arild Fuldseth)
Released
2000
Magic Bytes
Unknown (Proprietary)
Browser Support Comparison
| Browser | DjVu | FST-Image |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
DjVu
DjVu Strengths
- Unmatched compression ratios for high-resolution scanned documents (often 5 to 10 times smaller than equivalent JPEG/TIFF-based PDFs)
- Separates text layers cleanly from backgrounds, allowing for highly legible text even at low file sizes
- Embedded OCR (Optical Character Recognition) text layers allow for fast searching
Limitations
- Lacks native support in modern operating systems and web browsers, requiring third-party software
- Largely superseded by PDF/A and modern PDF compression standards in standard corporate workflows
- Not suitable for vector graphics or born-digital documents (like Word exports), where standard PDF is far superior
FST-Image
FST-Image Strengths
- Historically served as an optimized, compressed format for FAST's early multimedia and live streaming engines over constrained late-1990s bandwidth
Limitations
- Completely obsolete and non-functional in modern software ecosystems
- Undocumented, closed-source binary structure with zero support in modern image processing libraries
- Shares its file extension with several other distinct file types (such as FL Studio state files or FAST Search dictionaries), leading to easy misidentification
When to choose which format
DjVu
Use DjVu when…
- Scanned Books and Manuals
- Digital Libraries (e.g., Internet Archive)
- Historical Document Archiving
FST-Image
Use FST-Image when…
- Historical FAST Enterprise Search Indexing
- Legacy Proprietary Multimedia Streaming (late 1990s)
- Internal Media Transmission