Image MIME Reference
FST-Image
FAST Search & Transfer Image
image/vnd.fst
VS
Silicon Graphics Image
image/x-rgb
SGI-RGB
A complete technical comparison of FAST Search & Transfer Image and Silicon Graphics Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | FST-Image | SGI-RGB |
|---|---|---|
| Transparency (Alpha) | ✕ No | Yes |
| 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)
Silicon Graphics Image
image/x-rgb
Extension
.rgb.sgi.rgba.bw.int.inta
Container
SGI Image Header (512 bytes)
Compression
Uncompressed / Run-Length Encoding (RLE)
Algorithm
NoneScanline RLE
Color Depth
8-bit (Per Channel), 16-bit (Per Channel)
Developed by
Silicon Graphics, Inc. (Paul Haeberli)
Released
1988
Magic Bytes
01 DA
Browser Support Comparison
| Browser | FST-Image | SGI-RGB |
|---|---|---|
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
SGI-RGB
SGI-RGB Strengths
- Supports 16-bit precision per channel and an embedded alpha channel, making it ideal for the demanding compositing workflows of 1990s cinema VFX
- The scanline-based RLE compression was exceptionally fast to decode on classic MIPS-based SGI workstations
- Features a straightforward 512-byte header, making it relatively easy to parse and write custom decoders in C or Python
Limitations
- Completely obsolete and unsupported in modern web environments
- Replaced entirely by TIFF, OpenEXR, and PNG in modern visual effects and 3D rendering pipelines
- Lacks support for modern color management via ICC profiles or advanced EXIF metadata
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
SGI-RGB
Use SGI-RGB when…
- Legacy 3D Animation and VFX Textures
- Silicon Graphics IRIX Workstation Archival
- 1990s Medical Imaging