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Image MIME Reference
CMU-Raster

CMU Window Manager Raster

image/x-cmu-raster
VS

DjVu Document

image/vnd.djvu
DjVu

A complete technical comparison of CMU Window Manager Raster and DjVu Document — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature CMU-Raster DjVu
Transparency (Alpha) ✕ No Yes
Animation Support ✕ No ✕ No
Progressive Loading ✕ No Yes
HDR Support ✕ No ✕ No
EXIF Metadata ✕ No ✕ No
ICC Color Profile ✕ No ✕ No
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
Full CMU-Raster reference →
DjVu Document
image/vnd.djvu
Extension
.djvu.djv
Container Interchange File Format (IFF)
Compression JB2 (Bi-tonal Text) / IW44 (Wavelet Background) / BZZ (General Data/Text)
Algorithm
JB2IW44BZZ
Color Depth 1-bit (Foreground Text), 24-bit (Background)
Developed by AT&T Labs (Yann LeCun, Léon Bottou, Patrick Haffner, Paul G. Howard)
Released 1996
Magic Bytes
41 54 26 54 46 4F 52 4D
Full DjVu reference →

Browser Support Comparison

Browser CMU-Raster DjVu
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE 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
DjVu

DjVu Strengths

  • Unmatched compression ratios for high-resolution scanned documents (often 5 to 10 times smaller than equivalent JPEG/TIFF-based PDFs)
  • Separates text layers cleanly from backgrounds, allowing for highly legible text even at low file sizes
  • Embedded OCR (Optical Character Recognition) text layers allow for fast searching
Limitations
  • Lacks native support in modern operating systems and web browsers, requiring third-party software
  • Largely superseded by PDF/A and modern PDF compression standards in standard corporate workflows
  • Not suitable for vector graphics or born-digital documents (like Word exports), where standard PDF is far superior

When to choose which format

CMU-Raster
Use CMU-Raster when…
  • Historical UNIX / Andrew Project Archival
  • Legacy Academic Computing Research
DjVu
Use DjVu when…
  • Scanned Books and Manuals
  • Digital Libraries (e.g., Internet Archive)
  • Historical Document Archiving

More comparisons

CMU-Raster vs ACES → DjVu vs ACES → CMU-Raster vs APNG → DjVu vs APNG → CMU-Raster vs AVCI → DjVu vs AVCI → CMU-Raster vs AVCS → DjVu vs AVCS → CMU-Raster vs AVIF → DjVu vs AVIF → All comparisons →
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