Image MIME Reference
AOL-ART
AOL ART Image
image/x-jg
VS
Silicon Graphics Image
image/sgi
SGI
A complete technical comparison of AOL ART Image and Silicon Graphics Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | AOL-ART | SGI |
|---|---|---|
| Transparency (Alpha) | ✕ No | Yes |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | Yes | ✕ No |
| HDR Support | ✕ No | ✕ No |
| 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
Silicon Graphics Image
image/sgi
Extension
.sgi.rgb.rgba.bw.int.inta
Container
SGI Image Format
Compression
Uncompressed / Lossless (Run-Length Encoding)
Algorithm
RLENone
Color Depth
8-bit, 16-bit (Per Channel)
Developed by
Paul Haeberli (Silicon Graphics)
Released
1990
Magic Bytes
01 DA
Browser Support Comparison
| Browser | AOL-ART | SGI |
|---|---|---|
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
SGI
SGI Strengths
- Pioneered multi-channel and 16-bit per channel imaging capabilities required for high-end 1990s visual effects
- Extremely robust and simple header structure
- Reliable Run-Length Encoding provided solid lossless compression for flat-shaded 3D renders
Limitations
- Completely obsolete for modern web and application development
- Zero native web browser compatibility
- Largely replaced by TIFF and OpenEXR in modern professional VFX and 3D pipelines
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
SGI
Use SGI when…
- Legacy 3D Animation & VFX
- Silicon Graphics IRIX Workflows
- Historical CGI Archiving