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Image MIME Reference
CMU-Raster

CMU Window Manager Raster

image/x-cmu-raster
VS

Tagged Image File Format (Legacy MIME)

image/x-tiff
TIFF

A complete technical comparison of CMU Window Manager Raster and Tagged Image File Format (Legacy MIME) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature CMU-Raster TIFF
Transparency (Alpha) ✕ No Yes
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support ✕ No Yes
EXIF Metadata ✕ No Yes
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
Full CMU-Raster reference →
Tagged Image File Format (Legacy MIME)
image/x-tiff
Extension
.tiff.tif
Container IFD (Image File Directory) Tag Structure
Compression Uncompressed / LZW (Lossless) / ZIP / Deflate (Lossless) / PackBits (Lossless RLE) / JPEG (Lossy) / CCITT Group 3/4 (Fax/Document)
Algorithm
NoneLZWDeflatePackBitsJPEGCCITT
Color Depth 1-bit (Monochrome), 8-bit (Grayscale or Indexed), 16-bit (Per Channel), 32-bit (Float Per Channel)
Developed by Aldus Corporation (Later acquired by Adobe Systems)
Released 1986
Magic Bytes
49 49 2A 00 (Little-endian) or 4D 4D 00 2A (Big-endian)
Full TIFF reference →

Browser Support Comparison

Browser CMU-Raster TIFF
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
TIFF

TIFF Strengths

  • Universally accepted as the gold standard for high-fidelity archival and professional print workflows
  • Highly adaptable structure supports multiple pages (documents), layers, vast bit depths, and diverse compression algorithms within a single file
  • Unmatched support for rich metadata including EXIF, IPTC, XMP, and custom ICC color profiles
Limitations
  • Produces exceptionally large file sizes compared to modern web formats
  • The 'x-tiff' legacy MIME string forces developers to write extra validation logic to prevent strict security filters from rejecting valid uploads
  • The format's immense complexity means that many lightweight parsers only implement a subset of the specification, sometimes failing to read obscure compressions (like CCITT or old JPEG-in-TIFF)

When to choose which format

CMU-Raster
Use CMU-Raster when…
  • Historical UNIX / Andrew Project Archival
  • Legacy Academic Computing Research
TIFF
Use TIFF when…
  • Professional Print and Desktop Publishing
  • High-Resolution Archival Scanning
  • Master Copies of Digital Photography

More comparisons

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