Image MIME Reference
CMU-Raster
CMU Window Manager Raster
image/x-cmu-raster
VS
Microsoft Image Extension
image/vnd.mix
MIX
A complete technical comparison of CMU Window Manager Raster and Microsoft Image Extension — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | CMU-Raster | MIX |
|---|---|---|
| Transparency (Alpha) | ✕ No | Yes |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | ✕ No | ✕ No |
| EXIF Metadata | ✕ No | ✕ No |
| ICC Color Profile | ✕ No | Yes |
CMU Window Manager Raster
image/x-cmu-raster
Extension
.ras
Container
CMU Window Manager Bitmap
Compression
Uncompressed
Algorithm
None
Color Depth
1-bit (Monochrome), 8-bit (Indexed/Grayscale)
Developed by
Carnegie Mellon University (CMU)
Released
1980s
Magic Bytes
F1 00 40 BB
Microsoft Image Extension
image/vnd.mix
Extension
.mix
Container
Microsoft OLE Structured Storage (COM)
Compression
Proprietary (Internal JPEG/RLE)
Algorithm
JPEGDeflateProprietary
Color Depth
8-bit, 24-bit, 32-bit (RGBA)
Developed by
Microsoft Corporation
Released
1996
Magic Bytes
D0 CF 11 E0 A1 B1 1A E1
Browser Support Comparison
| Browser | CMU-Raster | MIX |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
CMU-Raster
CMU-Raster Strengths
- Incredibly simple, uncompressed binary structure that was easy for early, memory-constrained UNIX workstations to parse and render
Limitations
- Completely obsolete and unsupported outside of niche historical command-line tools like Netpbm
- The shared '.ras' file extension causes frequent file misidentification and system conflicts
- Lacks all modern imaging features, including metadata, compression, and alpha channel transparency
MIX
MIX Strengths
- Allowed early consumer software to non-destructively edit complex compositions involving photos, text, and vector clipart
- Shared an architecture with other Microsoft Office products, enabling deep integration (OLE embedding) into Word and PowerPoint at the time
Limitations
- Completely proprietary and undocumented, leading to a massive loss of historical data for users who archived their family photos in this project format
- Requires traversing a complex OLE filesystem just to extract the flattened raster image
- No support in modern image editors like Photoshop, GIMP, or web browsers
When to choose which format
CMU-Raster
Use CMU-Raster when…
- Historical UNIX / Andrew Project Archival
- Legacy Academic Computing Research
MIX
Use MIX when…
- Historical Microsoft Picture It! Projects
- Microsoft PhotoDraw 2000 Graphics
- Early 2000s Consumer Digital Scrapbooking