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Image MIME Reference
Compressed-XCF

Compressed GIMP XCF Image

image/x-compressed-xcf
VS

Digital Camera Raw (Generic Linux MIME)

image/x-dcraw
Generic-RAW

A complete technical comparison of Compressed GIMP XCF Image and Digital Camera Raw (Generic Linux MIME) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature Compressed-XCF Generic-RAW
Transparency (Alpha) Yes ✕ No
Animation Support Yes ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes Yes
EXIF Metadata Yes Yes
ICC Color Profile Yes Yes
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)
Full Compressed-XCF reference →
Digital Camera Raw (Generic Linux MIME)
image/x-dcraw
Extension
.raw
Container Varies (Predominantly TIFF/EP)
Compression Lossless / Uncompressed
Algorithm
Varies (Often Lossless JPEG ITU-T81 or uncompressed)
Color Depth 12-bit, 14-bit, 16-bit
Developed by freedesktop.org (MIME mapping) / Dave Coffin (dcraw tool)
Released 1997
Magic Bytes
Varies by vendor format
Full Generic-RAW reference →

Browser Support Comparison

Browser Compressed-XCF Generic-RAW
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
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
Generic-RAW

Generic-RAW Strengths

  • Provides a unified, highly useful catch-all MIME type for application developers who just need to know if a file is a raw image, rather than tracking 50+ individual camera extensions
  • Deeply integrated into the Linux desktop ecosystem, ensuring file manager thumbnails work seamlessly via tools like ufraw-thumbnailer
Limitations
  • Not an official IANA standard
  • Can cause conflicts where standard TIFF files are misidentified as raw camera data by over-aggressive MIME sniffers
  • The underlying 'dcraw' tool was abandoned by its creator in 2018 (though its successor, LibRaw, continues to maintain the ecosystem)

When to choose which format

Compressed-XCF
Use Compressed-XCF when…
  • GIMP Multi-layer Project Archival
  • Saving disk space for complex raster edits
  • Open-source graphic design workflows
Generic-RAW
Use Generic-RAW when…
  • Linux Desktop File Associations (GNOME/KDE)
  • Thumbnail Generation for Raw Images (UFRaw/LibRaw)
  • Server-side Image Processing Fallbacks

More comparisons

Compressed-XCF vs ACES → Generic-RAW vs ACES → Compressed-XCF vs APNG → Generic-RAW vs APNG → Compressed-XCF vs AVCI → Generic-RAW vs AVCI → Compressed-XCF vs AVCS → Generic-RAW vs AVCS → Compressed-XCF vs AVIF → Generic-RAW vs AVIF → All comparisons →
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