Free webp to jpg
EN
Image MIME Reference
APNG

Animated Portable Network Graphics

image/vnd.mozilla.apng
VS

Multi-resolution Seamless Image Database

image/x-mrsid-image
MrSID

A complete technical comparison of Animated Portable Network Graphics and Multi-resolution Seamless Image Database — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

APNG wins on browser support

Feature Support

Feature APNG MrSID
Transparency (Alpha) Yes Yes
Animation Support Yes ✕ No
Progressive Loading Yes Yes
HDR Support ✕ No ✕ No
EXIF Metadata Yes Yes
ICC Color Profile Yes Yes
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 →
Multi-resolution Seamless Image Database
image/x-mrsid-image
Extension
.sid
Container Proprietary MrSID Container
Compression Proprietary Wavelet (Lossy) / Proprietary Wavelet (Lossless)
Algorithm
Discrete Wavelet Transform (DWT)
Color Depth 8-bit (Grayscale), 24-bit (RGB), Multi-spectral (Multiple bands)
Developed by Los Alamos National Laboratory / LizardTech (Extensis)
Released 1992
Magic Bytes
6D 73 69 64
Full MrSID reference →

Browser Support Comparison

Browser APNG MrSID
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)
MrSID

MrSID Strengths

  • Incredible compression ratios enable multi-gigabyte geographical datasets to be stored on standard hard drives or transmitted easily
  • Multi-resolution architecture means panning and zooming across a massive map is completely fluid, as the system decodes only the visible quadrant at the required zoom level
  • Supports multi-spectral bands critical for remote sensing and agricultural GIS analysis
Limitations
  • Deeply proprietary; creating or decoding MrSID files typically requires expensive commercial software or the proprietary Extensis DSDK
  • Open-source geospatial libraries like GDAL require compiling against the proprietary SDK to legally enable MrSID support, causing licensing headaches for Linux server deployments
  • Not natively viewable on the web without specialized geospatial map servers (like GeoServer or MapServer) tiling the image into PNGs or JPEGs on the fly

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
MrSID
Use MrSID when…
  • Geographic Information Systems (GIS)
  • Satellite Imagery Archival
  • Aerial Orthophotography Mosaics

More comparisons

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