Image MIME Reference
AOL-ART
AOL ART Image
image/x-jg
VS
Flexible Image Transport System
image/fits
FITS
A complete technical comparison of AOL ART Image 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 | AOL-ART | FITS |
|---|---|---|
| Transparency (Alpha) | ✕ No | ✕ No |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | Yes | ✕ No |
| HDR Support | ✕ No | Yes |
| EXIF Metadata | ✕ No | ✕ No |
| ICC Color Profile | ✕ No | ✕ No |
AOL ART Image
image/x-jg
Extension
.art
Container
Johnson-Grace Proprietary
Compression
Proprietary Wavelet (Photos) / Proprietary Palette-based (Graphics)
Algorithm
Wavelet (similar to early JPEG 2000 concepts)Lossy DCT
Color Depth
8-bit (Indexed), 24-bit (RGB)
Developed by
Johnson-Grace Company (Acquired by AOL)
Released
1994
Magic Bytes
4A 47 03 00 or 4A 47 04 00
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 | AOL-ART | FITS |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
AOL-ART
AOL-ART Strengths
- Historically provided massive file size reductions (up to 3x smaller than JPEGs of the era) and highly optimized progressive rendering for 14.4k modems
- Enabled faster web browsing on the AOL network during the early days of the commercial internet
Limitations
- Completely proprietary, heavily patent-encumbered, and never officially reverse-engineered for the open-source community
- On-the-fly proxy compression ruined the visual fidelity of many 1990s websites for AOL users
- Virtually impossible to open on modern operating systems without installing niche, legacy image viewers
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
AOL-ART
Use AOL-ART when…
- Historical AOL Dial-up Web Browsing
- Legacy America Online Client Assets
- 1990s Internet Archival
FITS
Use FITS when…
- Astronomy & Astrophysics
- Space Telescope Data (Hubble, JWST)
- Scientific Data Archiving
- Spectroscopy