Lillian Schwartz, an American artist, is known for some of the first use of computers in computer developed art. Her best-known work is Mona Leo, her morphing of the image of a Leonardo self-portrait with the Mona Lisa. She has also written extensively about the topic of computer influence in art, and about art produced by computers. Schwartz was one of the first artists to experiment with computer images and computer effects on art. She worked closely with scientists in the 1970s in the early stages of computer development, and developed one of the first rock music videos. She also made one of the first digitised films to be shown as a work of art, her video Pixillation showing diagonal red squares and other shapes such as cones, pyramids on black on white backgrounds. This video is regarded as one of the most important early works of computer film art. Later on, during the 1980s, Schwartz made many experiments with artworks manipulating images using computer technology and creating some artworks of her own.