Image MIME Reference
DGN
MicroStation Design File
image/x-vnd.dgn
VS
Flexible Image Transport System
image/fits
FITS
A complete technical comparison of MicroStation Design File and Flexible Image Transport System — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | DGN | FITS |
|---|---|---|
| Transparency (Alpha) | Yes | ✕ No |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | ✕ No | Yes |
| EXIF Metadata | ✕ No | ✕ No |
| ICC Color Profile | ✕ No | ✕ No |
MicroStation Design File
image/x-vnd.dgn
Extension
.dgn
Container
Microsoft OLE Compound File (V8) / IGDS (V7)
Compression
Uncompressed / OLE Structured Storage
Algorithm
None
Color Depth
Indexed Color (V7), 24-bit True Color (V8)
Developed by
Intergraph (Originally) / Bentley Systems (Currently)
Released
1980
Magic Bytes
D0 CF 11 E0 A1 B1 1A E1 (For V8 DGN)
Flexible Image Transport System
image/fits
Extension
.fits.fit.fts
Container
FITS
Compression
Uncompressed / Tile Compressed (Rice, GZIP)
Algorithm
UncompressedRiceGZIPHcompress
Color Depth
8-bit, 16-bit, 32-bit, 64-bit (Float/Double)
Developed by
IAU FITS Working Group / NASA
Released
1981
Magic Bytes
53 49 4D 50 4C 45 20 20 3D 20
Browser Support Comparison
| Browser | DGN | FITS |
|---|---|---|
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✕ | ✕ |
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✕ | ✕ |
DGN
DGN Strengths
- Exceptionally robust at handling massive, coordinate-heavy infrastructure models that would frequently crash older versions of competing CAD software
- Deeply entrenched as the absolute standard format for many global departments of transportation and civil engineering firms
- V8 architecture supports boundless design plane coordinates, eliminating the physical scaling limitations of V7
Limitations
- Deeply proprietary format requiring complex third-party libraries (like the ODA SDK) to parse or write programmatically outside of the Bentley ecosystem
- V8's reliance on the archaic Microsoft OLE Compound File container makes file introspection cumbersome
- Cannot be rendered natively in web browsers without converting to WebGL/Canvas formats or SVG
FITS
FITS Strengths
- The undisputed global standard for archiving and sharing astronomical data
- Self-documenting: Headers are written in plain ASCII, ensuring data is readable decades later regardless of software
- Supports incredibly high dynamic range, N-dimensional arrays, and complex binary tables
Limitations
- No support in standard consumer software or web browsers
- Uncompressed raw FITS files from modern telescopes can be excessively large
- Does not use standard metadata models like EXIF or XMP, requiring specialized parsers
When to choose which format
DGN
Use DGN when…
- Civil Engineering and Plant Design
- Large-scale Architecture and Construction (AEC)
- 2D/3D Infrastructure Modeling
FITS
Use FITS when…
- Astronomy & Astrophysics
- Space Telescope Data (Hubble, JWST)
- Scientific Data Archiving
- Spectroscopy