Image MIME Reference
AZV
AirZip Accelerator Image
image/vnd.airzip.accelerator.azv
VS
X Bitmap (Legacy MIME Alias)
image/x-xbm
XBM
A complete technical comparison of AirZip Accelerator Image 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 | AZV | XBM |
|---|---|---|
| Transparency (Alpha) | ✕ No | Yes |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | Yes | ✕ No |
| HDR Support | ✕ No | ✕ No |
| EXIF Metadata | ✕ No | ✕ No |
| ICC Color Profile | ✕ No | ✕ No |
AirZip Accelerator Image
image/vnd.airzip.accelerator.azv
Extension
.azv
Container
Proprietary AirZip Container
Compression
Lossy (Proprietary) / Lossless (Proprietary)
Algorithm
AirZip Proprietary Compression
Color Depth
8-bit (Indexed), 24-bit (RGB)
Developed by
AirZip, Inc.
Released
1999
Magic Bytes
Unknown (Proprietary)
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 | AZV | XBM |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ |
✓
|
AZV
AZV Strengths
- Historically allowed internet users to browse the web up to 5x faster over 56k dial-up modems by drastically reducing image payload sizes
- Officially registered in the IANA vendor tree, preventing MIME type conflicts on early web proxy servers
Limitations
- Completely obsolete in the modern broadband era
- Closed-source and proprietary, meaning no modern image manipulation libraries (like ImageMagick or libvips) can decode it
- Zero support in standard web browsers
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
AZV
Use AZV when…
- Dial-up Web Acceleration
- Bandwidth Optimization (Historical)
- Legacy Proxy Servers
XBM
Use XBM when…
- X Window System (X11) Cursors and Icons
- Embedded C/C++ Firmware UI Assets
- Early 1990s Unix Web Graphics