XCF

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The XCF file format is the native image format of the GIMP image-editing program. It supports saving each layer, the current selection, channels, transparency, paths and guides. However, like the PSD file, the undo history is not saved in an XCF file.

The image data saved are compressed only by a simple RLE algorithm, but GIMP supports compressed files, using either gzip or bzip2. The compressed files can be opened as normal image files.

The XCF file format is mostly backward compatible. For example, GIMP 2.0 can save text in text layers while GIMP 1.2 can not. Text layers saved in GIMP 2.0 will open as ordinary image layers in GIMP 1.2.

The use of XCF as a data interchange format is not recommended by the GIMP developers, since the format reflects the GIMP's internal data structures, and there may be minor format changes in future versions. Thus the source code of the Gimp itself (which is freely available) is the reference documentation of the format. In addition, a collaborative effort between the GIMP developers and Krita developers is underway to design a raster file format modelled on the Open Document Format for use in both applications in a future version. However, Henning Makholm (see XCFTools below) has written a specification which is currently in draft form, which fully documents the format.

[edit] Software support

XCF is used as a file format in other programs besides the GIMP:

  • Seashore is a lightweight native MacOS X image editing program based on the GIMP
  • CinePaint is a fork of the GIMP with support for 16 bit and 32 bit floating point channels, and 16 bit integer channels. There are plans for CinePaint to move away from XCF as a file format. The XCF file format used in CinePaint has diverged from the GIMP's native format, so XCF files created in the GIMP can not be opened in Cinepaint, and vice versa.

Some image viewers and conversion software can read the format with varying degrees of success:

  • ImageMagick has an XCF reader module that can read single-layer non-indexed images.
  • Krita imports XCF files using the GraphicsMagick library.
  • ShowImg can display multi-layer non-indexed images.
  • Gwenview can display multi-layer non-indexed images.
  • GImageView [1] can display multi-layer non-indexed images.
  • XnView can display single-layer non-indexed images.
  • Scribus recently added XCF import support.
  • Inkscape recently added support for XCF import in the 0.44 release.
  • XCFTools [2] by HenningMakholm is a set of utilities which deformats and composes XCF images. It allows extraction of individual layers, or an entire composed image, as png or pnm.
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