Image MIME Reference
DWG
AutoCAD Drawing
image/vnd.dwg
VS
X Window Dump (Legacy MIME Alias)
image/x-xwindowdump
XWD
A complete technical comparison of AutoCAD Drawing and X Window Dump (Legacy MIME Alias) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | DWG | XWD |
|---|---|---|
| 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 |
AutoCAD Drawing
image/vnd.dwg
Extension
.dwg
Container
DWG Binary Container
Compression
Proprietary Binary Compression (LZ77 based in newer versions)
Algorithm
Proprietary (Autodesk ObjectDBX)
Color Depth
Vector (True Color / Indexed AutoCAD Color Index)
Developed by
Autodesk
Released
1982
Magic Bytes
41 43 31 30 (AC10)
X Window Dump (Legacy MIME Alias)
image/x-xwindowdump
Extension
.xwd.wd
Container
XWDHeader / XWDFileHeader Structure
Compression
Uncompressed
Algorithm
None
Color Depth
8-bit (Indexed), 16-bit (High Color), 24-bit (True Color), 32-bit (True Color with Alpha/Padding)
Developed by
MIT / X Consortium (X Window System)
Released
1987
Magic Bytes
00 00 00 64 (Typically indicates a 100-byte header size followed by version)
Browser Support Comparison
| Browser | DWG | XWD |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
DWG
DWG Strengths
- The undisputed industry standard for 2D drafting and basic 3D CAD modeling
- Highly optimized binary structure keeps file sizes relatively small compared to text-based CAD formats like DXF
- Supports incredibly complex datasets including external references (XREFs), dynamic blocks, and extensive custom metadata
Limitations
- It is a closed, proprietary format, making it difficult for third-party developers to support fully without licensing the Open Design Alliance (ODA) SDK
- Lacks native web or standard operating system previewer support
- Format versions change frequently (roughly every 3 years), breaking backward compatibility for older CAD software
XWD
XWD Strengths
- Provides an exact, raw pixel dump directly from the X11 display server memory without compression overhead
- Extremely fast for Unix environments to generate during low-level graphical debugging
Limitations
- Completely uncompressed, resulting in large, bloated file sizes
- Zero support in web browsers or modern desktop environments without specialized graphics translation tools
- Verbose legacy MIME strings like 'image/x-xwindowdump' require backend normalization in modern applications
When to choose which format
DWG
Use DWG when…
- Architectural Floor Plans
- Mechanical Engineering Models
- Civil Engineering Drafts
- 3D Product Designs
XWD
Use XWD when…
- X Window System (X11) Display Debugging and Screenshots
- Legacy Unix/Linux System Administration