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Image MIME Reference
AOL-ART

AOL ART Image

image/x-jg
VS

Animated Portable Network Graphics

image/vnd.mozilla.apng
APNG

A complete technical comparison of AOL ART Image and Animated Portable Network Graphics — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

APNG wins on browser support

Feature Support

Feature AOL-ART APNG
Transparency (Alpha) ✕ No Yes
Animation Support ✕ No Yes
Progressive Loading Yes Yes
HDR Support ✕ No ✕ No
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
Full AOL-ART reference →
Animated Portable Network Graphics
image/vnd.mozilla.apng
Extension
.apng.png
Container PNG Chunk Stream
Compression Deflate (Lossless)
Algorithm
Deflate (zlib)
Color Depth 8-bit (Indexed), 24-bit (TrueColor), 32-bit (RGBA)
Developed by Mozilla Corporation (Stuart Parmenter & Vladimir Vukićević)
Released 2004
Magic Bytes
89 50 4E 47 0D 0A 1A 0A
Full APNG reference →

Browser Support Comparison

Browser AOL-ART APNG
Chrome Chrome
✕
✓ 59
Firefox Firefox
✕
✓ 3
Safari Safari
✕
✓ 8
Edge Edge
✕
✓ 79
IE 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
APNG

APNG Strengths

  • Supports 8-bit alpha transparency, completely solving the ugly 'white halo' problem inherent to GIFs
  • Gracefully degrades; viewers that do not support APNG will render a perfectly valid, static PNG of the first frame
  • Provides lossless compression that retains absolute pixel-perfect quality for UI elements and line art
Limitations
  • Because it relies on lossless Deflate compression, file sizes for complex, video-like animations can be massive compared to lossy formats like WebP or AVIF
  • Was initially rejected by the official PNG group, delaying its adoption for nearly a decade
  • Lacks native hardware decoding acceleration, unlike video-based animated formats (like MP4 or WebM)

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
APNG
Use APNG when…
  • High-Quality Web Animations
  • Stickers (Apple iMessage, LINE, Discord)
  • UI Loaders with Alpha Transparency
  • GIF Replacement

More comparisons

AOL-ART vs ACES → APNG vs ACES → AOL-ART vs AVCI → APNG vs AVCI → AOL-ART vs AVCS → APNG vs AVCS → AOL-ART vs AVIF → APNG vs AVIF → All comparisons →
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