XCF (eXperimental Computing Facility)
The XCF Raster image file format
XCF is used by the open source GNU Image Manipulation Program (GIMP), an image formatting program that facilitates easy selection of channels, transparencies, paths and guides. It is used to saved the edited versions of images. It stores information such as layers, current position when saved, channels, paths, and other items used during editing. The name XCF origins from a group of students interested in advancing computer science.
Technical details of XCF files
GIMP supports the compressed XCF files, opening them as normal image files. XCF data is stored by a simple RLE algorithm which are supported by GIMP using gzip or bzip2. The XCF format is also a backward compatible file extension that supports all previous version files of GIMP, and may also be forward compatible in certain cases.