Image MIME Reference
FastBid
FastBid Sheet
image/vnd.fastbidsheet
VS
GIMP Image Format
image/x-xcf
XCF
A complete technical comparison of FastBid Sheet and GIMP Image Format — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | FastBid | XCF |
|---|---|---|
| Transparency (Alpha) | ✕ No | Yes |
| Animation Support | ✕ No | Yes |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | ✕ No | Yes |
| EXIF Metadata | ✕ No | Yes |
| ICC Color Profile | ✕ No | Yes |
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)
GIMP Image Format
image/x-xcf
Extension
.xcf
Container
GIMP Hierarchical Chunk Container
Compression
None / RLE (Run-Length Encoding) / Zlib / Deflate (In newer GIMP versions)
Algorithm
NoneRLEZlib
Color Depth
8-bit per channel, 16-bit per channel, 32-bit floating point
Developed by
Spencer Kimball, Peter Mattis, and the GIMP Development Team
Released
1995
Magic Bytes
67 69 6D 70 20 78 63 66
Browser Support Comparison
| Browser | FastBid | XCF |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
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
XCF
XCF Strengths
- Preserves all non-destructive editing elements, layer hierarchies, masks, and alpha channels across GIMP sessions
- Open and thoroughly documented specification within the open-source community, allowing third-party tools like Krita and ImageMagick to read project files
- Reliable magic byte header prevents misidentification
Limitations
- Massive file sizes because raw, unflattened layer bitmaps and masks are stored directly within the project archive
- Completely proprietary to the GIMP ecosystem for deep editing; cannot be natively rendered or parsed by web browsers
- Third-party software supporting XCF may occasionally struggle to render complex text layer adjustments or advanced layer blend modes identically to GIMP
When to choose which format
FastBid
Use FastBid when…
- Legacy Construction Blueprints
- FastBid Estimating Software
- Causing .fbs MIME Type Conflicts (FlatBuffers)
XCF
Use XCF when…
- GIMP Native Project Archival
- Layered Photo Editing and Graphic Design
- Intermediary Asset Preparation for Export