A note on discrete representation of lines.

In raster graphics a line must be drawn as a "discrete segment", a set of integer grid points that lie close to it. Equivalence classes of identically drawn lines are described in terms of Farey series; this treatment notably simplifies the previous work of Dorst and Smeulders. A log n algorithm to identify a line's equivalence class may be used to choose among precomputed n-pixel discrete segments. Then line-drawing may proceed in n-pixel blocks instead of the customary single-pixel steps.