XCF (file format) - Wikipedia
XCF, short for eXperimental Computing Facility, is the native image format of the GIMP image-editing program. It saves all of the data the program handles related to the image, including, among others, each layer, the current selection, channels, transparency, paths and guides. Prior to version 4 (GIMP 2.10.0, released on 2018-04-27), the saved image data are compressed only by a simple RLE algorithm, but GIMP supports compressed files, using gzip, bzip2, or xz. Th