Free webp to jpg
EN
Image MIME Reference
APNG

Animated Portable Network Graphics

image/vnd.mozilla.apng
VS

AutoCAD Slide

image/vnd.sld
SLD

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

APNG wins on browser support

Feature Support

Feature APNG SLD
Transparency (Alpha) Yes ✕ No
Animation Support Yes ✕ No
Progressive Loading Yes ✕ No
HDR Support ✕ No ✕ No
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
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 →
AutoCAD Slide
image/vnd.sld
Extension
.sld
Container AutoCAD Slide Container
Compression Uncompressed (Vector Instructions)
Algorithm
None
Color Depth 8-bit (AutoCAD Indexed Color)
Developed by Autodesk, Inc.
Released 1980s
Magic Bytes
41 75 74 6F 43 41 44 20 53 6C 69 64 65 0D 0A 1A 00
Full SLD reference →

Browser Support Comparison

Browser APNG SLD
Chrome Chrome
✓ 59
 ✕
Firefox Firefox
✓ 3
 ✕
Safari Safari
✓ 8
 ✕
Edge Edge
✓ 79
 ✕
IE IE (Legacy)
✕ ✕
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)
SLD

SLD Strengths

  • Allowed for instantaneous loading of highly complex architectural and engineering blueprints on low-memory MS-DOS systems
  • Easy-to-parse binary structure containing simple opcodes for drawing vectors and polygons
Limitations
  • Completely obsolete and heavily fragmented, largely replaced by PDF and lightweight web-based DXF viewers
  • Destructive 'snapshot' format irrevocably strips all useful, editable CAD geometry data from the original drawing
  • Zero support in web browsers or standard image processing libraries

When to choose which format

APNG
Use APNG when…
  • High-Quality Web Animations
  • Stickers (Apple iMessage, LINE, Discord)
  • UI Loaders with Alpha Transparency
  • GIF Replacement
SLD
Use SLD when…
  • Legacy AutoCAD Slideshows
  • AutoCAD Custom Icon Menus
  • Historical CAD Archival

More comparisons

APNG vs ACES → SLD vs ACES → APNG vs AVCI → SLD vs AVCI → APNG vs AVCS → SLD vs AVCS → APNG vs AVIF → SLD vs AVIF → All comparisons →
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