Image MIME Reference
Compressed-XCF
Compressed GIMP XCF Image
image/x-compressed-xcf
VS
FlashPix
image/vnd.fpx
FPX
A complete technical comparison of Compressed GIMP XCF Image and FlashPix — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | Compressed-XCF | FPX |
|---|---|---|
| Transparency (Alpha) | Yes | Yes |
| Animation Support | Yes | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | Yes | ✕ No |
| 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)
FlashPix
image/vnd.fpx
Extension
.fpx
Container
Microsoft OLE Structured Storage (COM)
Compression
JPEG (Lossy) / Uncompressed / Single-color (Solid)
Algorithm
JPEGNone
Color Depth
8-bit (Grayscale/Indexed), 24-bit (RGB), 32-bit (CMYK/RGBA)
Developed by
Eastman Kodak, Microsoft, Hewlett-Packard, Live Picture
Released
1996
Magic Bytes
D0 CF 11 E0 A1 B1 1A E1
Browser Support Comparison
| Browser | Compressed-XCF | FPX |
|---|---|---|
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✕ | ✕ |
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✕ | ✕ |
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✕ | ✕ |
|
|
✕ | ✕ |
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✕ | ✕ |
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
FPX
FPX Strengths
- Allowed early, low-RAM computers to view and edit massive, high-resolution digital photos instantly by only loading the needed tiles and resolutions
- Pioneered the multi-resolution pyramid and tiling concepts heavily used today in modern deep-zoom and web mapping applications (like Google Maps)
Limitations
- Completely obsolete and unsupported by modern web browsers or operating systems
- Uses the complex, proprietary Microsoft OLE container format, making it incredibly difficult to parse or extract data from without dedicated legacy libraries
- Prone to being misidentified by MIME sniffers as an old Microsoft Office document
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
FPX
Use FPX when…
- Legacy Digital Photography
- Kodak Picture CDs (Historical)
- Early High-Resolution Image Viewers