Image MIME Reference
DWG
AutoCAD Drawing
image/vnd.dwg
VS
Microsoft Document Imaging
image/vnd.ms-modi
MODI
A complete technical comparison of AutoCAD Drawing and Microsoft Document Imaging — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | DWG | MODI |
|---|---|---|
| Transparency (Alpha) | Yes | ✕ No |
| 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)
Microsoft Document Imaging
image/vnd.ms-modi
Extension
.mdi
Container
TIFF Variant
Compression
LZW / Proprietary MS Compression
Algorithm
LZW (Modified)
Color Depth
1-bit (Monochrome), 8-bit (Grayscale), 24-bit (RGB)
Developed by
Microsoft Corporation
Released
2001
Magic Bytes
49 49 2A 00
Browser Support Comparison
| Browser | DWG | MODI |
|---|---|---|
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
MODI
MODI Strengths
- Historically provided an excellent all-in-one scanned document format with built-in OCR and annotations before PDF editing became universally accessible
- Tightly integrated with Microsoft Office and SharePoint workflows in the early 2000s
Limitations
- Completely proprietary and obsolete; Microsoft abandoned it in favor of standard TIFF and PDF
- Causes widespread identification conflicts since its file signature is identical to a standard TIFF
- Extremely difficult to open on modern operating systems without relying on third-party conversion utilities
When to choose which format
DWG
Use DWG when…
- Architectural Floor Plans
- Mechanical Engineering Models
- Civil Engineering Drafts
- 3D Product Designs
MODI
Use MODI when…
- Legacy Scanned Document Archival
- Microsoft Office XP/2003/2007 Workflows
- Embedded OCR Text Storage