Image MIME Reference
AOL-ART
AOL ART Image
image/x-jg
VS
Adobe Digital Negative
image/x-adobe-dng
DNG
A complete technical comparison of AOL ART Image and Adobe Digital Negative — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | AOL-ART | DNG |
|---|---|---|
| Transparency (Alpha) | ✕ No | Yes |
| Animation Support | ✕ No | ✕ No |
| 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
Adobe Digital Negative
image/x-adobe-dng
Extension
.dng
Container
TIFF/EP
Compression
Lossless JPEG / Deflate / Lossy JPEG (DNG 1.4+)
Algorithm
Lossless JPEG (Standard)Lossy JPEG (Compression option)Uncompressed
Color Depth
12-bit, 14-bit, 16-bit, 32-bit (Floating Point HDR)
Developed by
Adobe Systems
Released
2004
Magic Bytes
49 49 2A 00 or 4D 4D 00 2A
Browser Support Comparison
| Browser | AOL-ART | DNG |
|---|---|---|
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
DNG
DNG Strengths
- Openly documented specification guarantees long-term archival accessibility, freeing photographers from proprietary manufacturer lock-in
- Lossless compression algorithms often result in files 15-20% smaller than uncompressed proprietary raw formats
- Natively supported by modern smartphone operating systems (iOS and Android) for high-end mobile photography
Limitations
- Conversion from proprietary raw to DNG takes processing time and can strip specific, proprietary manufacturer metadata (like active D-Lighting or in-camera lens corrections)
- File sizes are massive compared to standard JPEGs or HEIC files
- Cannot be rendered natively in web browsers without server-side processing or WebAssembly decoders
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
DNG
Use DNG when…
- Digital Photography Archival
- Mobile Raw Capture (iOS ProRAW / Android Camera2 API)
- Cross-Platform Raw Editing Workflows