Image MIME Reference
AOL-ART
AOL ART Image
image/x-jg
VS
Compressed GIMP XCF Image
image/x-compressed-xcf
Compressed-XCF
A complete technical comparison of AOL ART Image and Compressed GIMP XCF Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | AOL-ART | Compressed-XCF |
|---|---|---|
| Transparency (Alpha) | ✕ No | Yes |
| Animation Support | ✕ No | Yes |
| Progressive Loading | Yes | ✕ No |
| HDR Support | ✕ No | Yes |
| EXIF Metadata | ✕ No | Yes |
| ICC Color Profile | ✕ No | Yes |
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
Compressed GIMP XCF Image
image/x-compressed-xcf
Extension
.xcf.gz.xcf.bz2.xcfgz.xcfbz2
Container
Gzip or Bzip2 Archive
Compression
Gzip (Deflate) / Bzip2
Algorithm
DeflateBWT (Burrows-Wheeler)
Color Depth
8-bit (Per Channel), 16-bit (Integer/Floating Point), 32-bit (Integer/Floating Point)
Developed by
The GIMP Team
Released
1995
Magic Bytes
1F 8B 08 (gzip) or 42 5A 68 (bzip2)
Browser Support Comparison
| Browser | AOL-ART | Compressed-XCF |
|---|---|---|
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
Compressed-XCF
Compressed-XCF Strengths
- Drastically reduces the massive file sizes of standard XCF project files, saving significant disk space
- Preserves 100% of the non-destructive editing data (layers, masks, paths, guides) from the GIMP workspace
- Uses standard, universally supported compression algorithms (gzip/bzip2) meaning the archive can be rescued or extracted by standard OS tools if GIMP is unavailable
Limitations
- Increases file load and save times due to the CPU overhead required to compress and decompress the massive pixel arrays
- Impossible for automated tools to parse metadata or dimensions without first unarchiving the payload into memory
- File extension combinations (.xcf.gz) can confuse basic MIME sniffers which stop reading at the .gz extension
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
Compressed-XCF
Use Compressed-XCF when…
- GIMP Multi-layer Project Archival
- Saving disk space for complex raster edits
- Open-source graphic design workflows