This offset lithograph, by Manfred Mohr (born 1938, Germany), is from a plotter drawing produced using a computer program written by the artist. A plotter is a mechanical device that holds a pen or brush and is linked to a computer that controls its movements.

The computer program was based on a series of decision making processes that were used to structure the image. The artist deliberately wrote random variables into the process to allow the computer to make certain choices from a given number of options. For this particular image, the computer plotted a set of random points above a horizontal line, which it connected to form a continuous line. It then carried out small transformations to each line until they reached the straight horizontal line at the base of each square.

Mohr began life as an expressionist painter and jazz musician but in the 1960s began exploring geometric form, and moved towards a more objective, systematic way of working that anticipated his use of the computer. Mohr underpins his computer programs, or algorithms, with precise mathematical logic. The computer enables Mohr to create very complex algorithms which would otherwise be too difficult and time consuming for humans to process.