Image MIME Reference
FST-Image
FAST Search & Transfer Image
image/vnd.fst
VS
SealedMedia Portable Network Graphics
image/vnd.sealed.png
Sealed-PNG
A complete technical comparison of FAST Search & Transfer Image and SealedMedia Portable Network Graphics — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | FST-Image | Sealed-PNG |
|---|---|---|
| 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 |
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)
SealedMedia Portable Network Graphics
image/vnd.sealed.png
Extension
.spng.sealed-png
Container
SealedMedia / Oracle IRM Wrapper
Compression
Encrypted Payload (Deflate)
Algorithm
AES EncryptionDeflate (Internal PNG payload)
Color Depth
Encrypted Payload
Developed by
SealedMedia (Acquired by Oracle Corporation)
Released
Late 1990s / Early 2000s
Magic Bytes
Unknown (Proprietary SealedMedia Container)
Browser Support Comparison
| Browser | FST-Image | Sealed-PNG |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
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
Sealed-PNG
Sealed-PNG Strengths
- Provided absolute control over intellectual property, allowing enterprise administrators to instantly revoke viewing rights of a local file globally
- Detailed audit trails tracked exactly who opened the image, when, and from what IP address
Limitations
- Completely proprietary and relies on a central authentication server; if the server goes offline, the image is permanently inaccessible
- No support in modern operating systems, web browsers, or standard image editing software without installing heavy enterprise DRM clients
- Oracle effectively deprecated the IRM product line, leaving legacy sealed documents difficult to recover
When to choose which format
FST-Image
Use FST-Image when…
- Historical FAST Enterprise Search Indexing
- Legacy Proprietary Multimedia Streaming (late 1990s)
- Internal Media Transmission
Sealed-PNG
Use Sealed-PNG when…
- Enterprise Information Rights Management (IRM)
- Secure Corporate Intellectual Property Distribution
- Revocable Medical or Legal Imaging