Image MIME Reference
CGM
Computer Graphics Metafile
image/cgm
VS
Compressed GIMP XCF Image
image/x-compressed-xcf
Compressed-XCF
A complete technical comparison of Computer Graphics Metafile and Compressed GIMP XCF Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | CGM | Compressed-XCF |
|---|---|---|
| Transparency (Alpha) | Yes | Yes |
| Animation Support | ✕ No | Yes |
| 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)
Compressed GIMP XCF Image
image/x-compressed-xcf
Extension
.xcf.gz.xcf.bz2.xcfgz.xcfbz2
Container
Gzip or Bzip2 Archive
Compression
Gzip (Deflate) / Bzip2
Algorithm
DeflateBWT (Burrows-Wheeler)
Color Depth
8-bit (Per Channel), 16-bit (Integer/Floating Point), 32-bit (Integer/Floating Point)
Developed by
The GIMP Team
Released
1995
Magic Bytes
1F 8B 08 (gzip) or 42 5A 68 (bzip2)
Browser Support Comparison
| Browser | CGM | Compressed-XCF |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
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
Compressed-XCF
Compressed-XCF Strengths
- Drastically reduces the massive file sizes of standard XCF project files, saving significant disk space
- Preserves 100% of the non-destructive editing data (layers, masks, paths, guides) from the GIMP workspace
- Uses standard, universally supported compression algorithms (gzip/bzip2) meaning the archive can be rescued or extracted by standard OS tools if GIMP is unavailable
Limitations
- Increases file load and save times due to the CPU overhead required to compress and decompress the massive pixel arrays
- Impossible for automated tools to parse metadata or dimensions without first unarchiving the payload into memory
- File extension combinations (.xcf.gz) can confuse basic MIME sniffers which stop reading at the .gz extension
When to choose which format
CGM
Use CGM when…
- Technical Illustrations
- Aerospace & Defense (S1000D)
- CAD/CAM
- Geophysics
Compressed-XCF
Use Compressed-XCF when…
- GIMP Multi-layer Project Archival
- Saving disk space for complex raster edits
- Open-source graphic design workflows