Image MIME Reference
WBMP
Wireless Bitmap
image/vnd.wap.wbmp
VS
X Bitmap (Legacy MIME Alias)
image/x-xbm
XBM
A complete technical comparison of Wireless Bitmap and X Bitmap (Legacy MIME Alias) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | WBMP | XBM |
|---|---|---|
| Transparency (Alpha) | ✕ No | Yes |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | ✕ No | ✕ No |
| EXIF Metadata | ✕ No | ✕ No |
| ICC Color Profile | ✕ No | ✕ No |
Wireless Bitmap
image/vnd.wap.wbmp
Extension
.wbmp
Container
WBMP Type 0
Compression
Uncompressed
Algorithm
None
Color Depth
1-bit (Monochrome)
Developed by
WAP Forum (Now Open Mobile Alliance)
Released
1999
Magic Bytes
00 00
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')
Browser Support Comparison
| Browser | WBMP | XBM |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ |
✓
|
WBMP
WBMP Strengths
- Extremely low processing overhead made it perfectly suited for the ultra-low-power CPUs of late 1990s mobile devices
- Tightly integrated into the WML (Wireless Markup Language) stack, enabling the first functional mobile internet experiences
Limitations
- Completely obsolete and lacks support in modern operating systems and browsers
- Limited entirely to 1-bit black and white (0 for black, 1 for white) with zero support for grayscale, color, or transparency
- The lack of a strong file header signature makes automated MIME type detection highly unreliable
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
WBMP
Use WBMP when…
- Legacy WML (Wireless Markup Language) Mobile Sites
- Early Mobile Phone Icons and Operator Logos
- Historical WAP Archival
XBM
Use XBM when…
- X Window System (X11) Cursors and Icons
- Embedded C/C++ Firmware UI Assets
- Early 1990s Unix Web Graphics