Image MIME Reference
FITS
Flexible Image Transport System
image/fits
VS
JPEG XR (HD Photo)
image/vnd.ms-photo
JPEG-XR
A complete technical comparison of Flexible Image Transport System and JPEG XR (HD Photo) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | FITS | JPEG-XR |
|---|---|---|
| Transparency (Alpha) | ✕ No | Yes |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | Yes |
| HDR Support | Yes | Yes |
| EXIF Metadata | ✕ No | Yes |
| ICC Color Profile | ✕ No | Yes |
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
JPEG XR (HD Photo)
image/vnd.ms-photo
Extension
.jxr.wdp.hdp
Container
TIFF-like Image File Directory (IFD)
Compression
Lossy (Lapped Bi-orthogonal Transform) / Lossless
Algorithm
Lapped Bi-orthogonal Transform (LBT)
Color Depth
8-bit (Grayscale, RGB, CMYK), 16-bit, 32-bit Floating Point (HDR)
Developed by
Microsoft Corporation (later Joint Photographic Experts Group)
Released
2006
Magic Bytes
49 49 BC 01
Browser Support Comparison
| Browser | FITS | JPEG-XR |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ |
✓
|
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
JPEG-XR
JPEG-XR Strengths
- Excellent support for 16-bit and 32-bit floating-point HDR images without massive file size bloat
- Native support for alpha transparency, which standard JPEG fundamentally lacks
- Computational complexity for decoding/encoding is relatively low, making it hardware-friendly
Limitations
- Suffered a complete failure of adoption in the web browser market outside of Microsoft's ecosystem
- Fully superseded by modern, open formats like WebP, AVIF, and JPEG XL which offer better compression and universal browser support
- Multiple file extensions (.wdp, .hdp, .jxr) and MIME types cause confusion and parsing fragmentation
When to choose which format
FITS
Use FITS when…
- Astronomy & Astrophysics
- Space Telescope Data (Hubble, JWST)
- Scientific Data Archiving
- Spectroscopy
JPEG-XR
Use JPEG-XR when…
- Legacy Windows Desktop Backgrounds
- XPS (XML Paper Specification) Documents
- Early High Dynamic Range (HDR) Photography
- DirectX Textures