Free webp to jpg
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Image MIME Reference
APNG

Animated Portable Network Graphics

image/vnd.mozilla.apng
VS

X Bitmap (Legacy MIME Alias)

image/x-xbm
XBM

A complete technical comparison of Animated Portable Network Graphics and X Bitmap (Legacy MIME Alias) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

APNG wins on browser support

Feature Support

Feature APNG XBM
Transparency (Alpha) Yes Yes
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 →
X Bitmap (Legacy MIME Alias)
image/x-xbm
Extension
.xbm
Container C Source Code Header (.h)
Compression Uncompressed (Source Code)
Algorithm
None
Color Depth 1-bit (Monochrome)
Developed by MIT / X Consortium (X Window System)
Released 1988
Magic Bytes
23 64 65 66 69 6e 65 (ASCII '#define')
Full XBM reference →

Browser Support Comparison

Browser APNG XBM
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)
XBM

XBM Strengths

  • Can be compiled directly into C or C++ source code without needing an external file loader or binary asset manager
  • Human-readable structure allows developers to inspect, edit, or hand-craft tiny icons directly within a text editor
  • Extremely predictable and lightweight for 1-bit hardware displays and embedded systems
Limitations
  • Strictly limited to 1-bit monochrome (black and white) graphics with no gray or color support
  • Text-based C syntax creates massive file bloat compared to binary 1-bit formats like PBM
  • Completely deprecated in modern web browsers and desktop GUI frameworks

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
XBM
Use XBM when…
  • X Window System (X11) Cursors and Icons
  • Embedded C/C++ Firmware UI Assets
  • Early 1990s Unix Web Graphics

More comparisons

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