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Image MIME Reference
CGM

Computer Graphics Metafile

image/cgm
VS

Panasonic RAW Image

image/x-panasonic-raw
Panasonic-RAW-(RW2)

A complete technical comparison of Computer Graphics Metafile and Panasonic RAW Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature CGM Panasonic-RAW-(RW2)
Transparency (Alpha) Yes ✕ No
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support ✕ No Yes
EXIF Metadata ✕ No Yes
ICC Color Profile Yes Yes
Computer Graphics Metafile
image/cgm
Extension
.cgm
Container CGM
Compression Uncompressed / Binary / Character / Clear Text
Algorithm
Deflate (in some WebCGM profiles)
Color Depth 8-bit, 16-bit, 24-bit, 32-bit
Developed by ISO / IEC
Released 1987
Magic Bytes
00 20 (Binary) / 42 45 47 49 4E 20 4D 45 54 41 46 49 4C 45 (Clear Text)
Full CGM reference →
Panasonic RAW Image
image/x-panasonic-raw
Extension
.raw.rw2
Container TIFF-based (Proprietary)
Compression Uncompressed / Panasonic Proprietary Lossless
Algorithm
NoneProprietary Lossless
Color Depth 12-bit (Per Channel), 14-bit (Per Channel), 16-bit (Per Channel - High-res mode)
Developed by Panasonic Corporation
Released 2004
Magic Bytes
Older RAW: 49 49 2A 00 | Newer RW2: 49 49 55 00
Full Panasonic-RAW-(RW2) reference →

Browser Support Comparison

Browser CGM Panasonic-RAW-(RW2)
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
CGM

CGM Strengths

  • Strictly standardized by ISO, ensuring long-term archiving and cross-platform compatibility in engineering
  • Excellent support for rich metadata, hyperlinks, and technical hotspots via the WebCGM profile
  • Can store complex 2D geometry, rasters, and text in a single lightweight file
Limitations
  • Multiple encoding schemes (Binary, Character, Clear Text) make parser development difficult
  • Zero native support in modern web browsers without third-party plugins
  • Largely replaced by SVG for general-purpose 2D vector graphics on the web
Panasonic-RAW-(RW2)

Panasonic-RAW-(RW2) Strengths

  • Retains maximum sensor data, allowing significant recovery of highlights and shadows compared to in-camera JPEGs
  • Modern RW2 files embed proprietary lens correction profiles (distortion, vignetting, chromatic aberration) that raw converters can automatically apply
  • The unique 'IIU' signature on RW2 files makes programmatic identification extremely reliable compared to other TIFF-spoofing raw formats
Limitations
  • Proprietary format requires continuous updates to third-party processing engines whenever Panasonic releases a new Lumix camera
  • Produces very large file sizes, particularly when using Panasonic's High-Resolution multi-shot modes
  • Cannot be directly embedded into web pages or used in standard HTML/CSS contexts

When to choose which format

CGM
Use CGM when…
  • Technical Illustrations
  • Aerospace & Defense (S1000D)
  • CAD/CAM
  • Geophysics
Panasonic-RAW-(RW2)
Use Panasonic-RAW-(RW2) when…
  • Professional Digital Photography
  • Non-destructive Image Post-Processing
  • High Dynamic Range (HDR) Lumix Archival

More comparisons

CGM vs ACES → Panasonic-RAW-(RW2) vs ACES → CGM vs APNG → Panasonic-RAW-(RW2) vs APNG → CGM vs AVCI → Panasonic-RAW-(RW2) vs AVCI → CGM vs AVCS → Panasonic-RAW-(RW2) vs AVCS → CGM vs AVIF → Panasonic-RAW-(RW2) vs AVIF → All comparisons →
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