The "X-ray" tradition in Aboriginal art is thought to have developed around 2000 B.C. and continues to the present day. As its name implies, the X-ray style depicts animals or human figures in which the internal organs and bone structures are clearly visible. X-ray art includes sacred images of ancestral supernatural beings as well as secular works depicting fish and animals that were important food sources. In many instances, the paintings show fish and game species from the local area. Through the creation of X-ray art, Aboriginal painters express their ongoing relationships with the natural and supernatural worlds.
To create an X-ray image, the artist begins by painting a silhouette of the figure, often in white, and then adding the internal details in red or yellow. For red, yellow, and white paints, the artist uses natural ocher pigments mined from mineral deposits, while black is drived from charcoal. Early X-ray images depict the backbone, ribs, and internal organs of humans and animals. Later examples also include features such as muscle masses, body fat, optic nerves, and breast milk in women. Some works created after European contact even show rifles with bullets visible inside them.
X-ray paintings occur primarily in the shallow caves and rock shelters in the western part of Arnhem Land in northern Australia. One of the best known galleries of X-ray painting is at Ubirr, which served as a camping place during the annual wet season. Similar X-ray paintings are found throughout the region, including the site of Injaluk near the community of Gunbalanya (also called Oenpelli), whose contemporary Aboriginal artists continue to create works in the X-ray tradition.