XCF is a file format from the raster graphics category developed by GIMP. The specified extension is considered the standard image format specifically for the GIMP graphics editor. In its characteristics, XCF is very similar to the PSD raster graphics format, which is native to Photoshop. XCF files do not support the function of saving the "history of cancellations", however, for other characteristics, they are highly praised by experts. So, they retain channels, transparency, layers, guides. Data compression in this format is lossless. The name of the format is associated with the organization of experimental computing (eXperimental Computing Facility) of the University of California, Berkeley.
PCX is one of the first bitmap image formats developed by ZSoft for the PC Paintbrush program. This is the original bitmap format for the DOS / Windows platform. It supports monochrome single-bit black and white images, an eight-bit gray scale, indexed color images, and full-color 24-bit RGB model images. But there is no support for additional color and alpha channels, clipping paths, color management. The format provides for the application of the simplest compression algorithm (RLE) so that information is not lost. Now it has a purely historical significance. The PCX file format has been replaced by newer image formats. However, the format is still used in separate applications in order to scan and send faxes. PCX multi-page fax documents use the .DCX extension. Most DOS-based programs are suitable for viewing PCX (PC eXchange) files. In particular, the viewer Norton Commander. The big drawback of the PCX format is that it has too many versions. This can be explained by the fact that the PCX standard is open, and therefore it has been widely used by most independent software developers. And therefore it is constantly updated.