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Image MIME Reference
XBM

X Bitmap (Legacy MIME Alias)

image/x-xbm
VS

X Pixmap

image/x-xpixmap
XPM

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

Equal browser support

Feature Support

Feature XBM XPM
Transparency (Alpha) Yes Yes
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support ✕ No ✕ No
EXIF Metadata ✕ No ✕ No
ICC Color Profile ✕ No ✕ No
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 →
X Pixmap
image/x-xpixmap
Extension
.xpm
Container C Source Code Header (.c / .h)
Compression Uncompressed (Source Code)
Algorithm
None
Color Depth Indexed Color (Custom Palette with RGB and Alpha 'None')
Developed by Daniel Dardailler and Colas Nahaboo (Bull / X Consortium)
Released 1989
Magic Bytes
2F 2A 20 58 50 4D 20 2A 2F (ASCII '/* XPM */')
Full XPM reference →

Browser Support Comparison

Browser XBM XPM
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✓
✓
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
XPM

XPM Strengths

  • Can be compiled directly into C or C++ source code without requiring an external asset loading mechanism
  • Human-readable palette mapping allows developers to inspect, modify, or hand-craft icons directly within a text editor
  • Native support for color palettes and transparency via the 'None' keyword
Limitations
  • Extremely inefficient storage structure for large images, resulting in massive file bloat compared to binary formats like PNG
  • Completely obsolete and unsupported in modern web browsers
  • Parsing overhead requires compiling or interpreting text-based color tables at runtime

When to choose which format

XBM
Use XBM when…
  • X Window System (X11) Cursors and Icons
  • Embedded C/C++ Firmware UI Assets
  • Early 1990s Unix Web Graphics
XPM
Use XPM when…
  • X Window System (X11) Application Icons and Cursors
  • Embedded C/C++ Firmware Color UI Assets
  • Early Linux Desktop Environment Themes

More comparisons

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