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Image MIME Reference
Compressed-XCF

Compressed GIMP XCF Image

image/x-compressed-xcf
VS

Pixologic ZBrush PCX

image/vnd.zbrush.pcx
ZBrush-PCX

A complete technical comparison of Compressed GIMP XCF Image and Pixologic ZBrush PCX — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature Compressed-XCF ZBrush-PCX
Transparency (Alpha) Yes ✕ No
Animation Support Yes ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes ✕ No
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
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 →
Pixologic ZBrush PCX
image/vnd.zbrush.pcx
Extension
.pcx
Container ZSoft PCX
Compression Run-Length Encoding (RLE)
Algorithm
ZSoft Run-Length Encoding (RLE)
Color Depth 8-bit (Grayscale), 24-bit (RGB)
Developed by ZSoft (Format) / Pixologic (MIME Registration)
Released 1985
Magic Bytes
0A 05 01 08
Full ZBrush-PCX reference →

Browser Support Comparison

Browser Compressed-XCF ZBrush-PCX
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
ZBrush-PCX

ZBrush-PCX Strengths

  • Extremely simple, lossless RLE compression makes it trivial to parse and encode programmatically
  • Universally supported by almost every 2D image editor created since the 1990s
Limitations
  • Completely obsolete for modern 3D workflows, which require 16-bit or 32-bit floating-point precision (like OpenEXR or TIFF) to avoid stepping artifacts in displacement maps
  • No support for modern metadata (EXIF/XMP) or native alpha channels
  • Zero native support in modern web browsers

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
ZBrush-PCX
Use ZBrush-PCX when…
  • Legacy ZBrush Alpha Brushes
  • 8-bit Grayscale Displacement Maps
  • ZBrush Texture Exports

More comparisons

Compressed-XCF vs ACES → ZBrush-PCX vs ACES → Compressed-XCF vs APNG → ZBrush-PCX vs APNG → Compressed-XCF vs AVCI → ZBrush-PCX vs AVCI → Compressed-XCF vs AVCS → ZBrush-PCX vs AVCS → Compressed-XCF vs AVIF → ZBrush-PCX vs AVIF → All comparisons →
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