Image MIME Reference
CMU-Raster
CMU Window Manager Raster
image/x-cmu-raster
VS
FastBid Sheet
image/vnd.fastbidsheet
FastBid
A complete technical comparison of CMU Window Manager Raster and FastBid Sheet — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | CMU-Raster | FastBid |
|---|---|---|
| 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 |
CMU Window Manager Raster
image/x-cmu-raster
Extension
.ras
Container
CMU Window Manager Bitmap
Compression
Uncompressed
Algorithm
None
Color Depth
1-bit (Monochrome), 8-bit (Indexed/Grayscale)
Developed by
Carnegie Mellon University (CMU)
Released
1980s
Magic Bytes
F1 00 40 BB
FastBid Sheet
image/vnd.fastbidsheet
Extension
.fbs
Container
Proprietary FastBid Container
Compression
Proprietary
Algorithm
Unknown
Color Depth
Unknown
Developed by
FastBid, Inc. (Scott Becker)
Released
Late 1990s
Magic Bytes
Unknown (Proprietary)
Browser Support Comparison
| Browser | CMU-Raster | FastBid |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
CMU-Raster
CMU-Raster Strengths
- Incredibly simple, uncompressed binary structure that was easy for early, memory-constrained UNIX workstations to parse and render
Limitations
- Completely obsolete and unsupported outside of niche historical command-line tools like Netpbm
- The shared '.ras' file extension causes frequent file misidentification and system conflicts
- Lacks all modern imaging features, including metadata, compression, and alpha channel transparency
FastBid
FastBid Strengths
- Historically allowed the FastBid application to securely associate and load proprietary construction plans within its ecosystem
Limitations
- Completely obsolete and unsupported in modern software environments
- The official IANA registration of the .fbs extension causes widespread false positives, breaking modern parsers, text editors, and AI SDKs attempting to read FlatBuffers schemas
When to choose which format
CMU-Raster
Use CMU-Raster when…
- Historical UNIX / Andrew Project Archival
- Legacy Academic Computing Research
FastBid
Use FastBid when…
- Legacy Construction Blueprints
- FastBid Estimating Software
- Causing .fbs MIME Type Conflicts (FlatBuffers)