Open PSD File

XCF File

XCF is a container image data format used by GIMP. XCF name originates from Experimental Computing Facility of the University of California at Berkley.

General XCF file consists of stack of channels and layers on a canvas. Canvas is a rectangular viewport where layers and channels are projected. Canvas dimensions and other properties are stored in XCF file header.

Channels

Channels store individual color channel information. For example, image stored in red, green, blue (RGB) format contains three color channels: red, green, and blue. Each channel contains information about intensity of the specific color. Besides standard RGB channels custom channels could also be stored.

Layers

Layer specifies a rectangular set of pixels with a specific position on a canvas. Each layer has an alpha component specified for each pixel. This allows user to control transparency of the layer. Other properties like visibility, group, and other editing flags could be saved for each layer.

Selection

Selection in XCF is stored as a channel where pixels with 255 value are part of the selection and pixels with 0 are not. Floating selection is a selection which is attached to a specific channel, layer or layer mask.

Properties

XCF file can have multiple simple and advanced properties attached to it. Vector paths, curves and text are stored as properties in XCF file. Each property has a type attached to it which specifies what kind of information is stored in it.

File Structure

Each XCF file starts with a header structure which contains file type watermark, XFC file version, width and height of an image, color mode and list of other image properties. Properties can include image color map, compression type, guides positions, curved and vector paths, image resolution details. Also, image header contains list of pointers to all layers in an image. Each layer structure contains width, height, color mode and name of the layer. Layer can also contain additional properties such as links to channels, masks, floating selection, groups, blending mode and more.

Full specification of XCF file format is available at XCF page on gnome.org.