Algorithm of Bresenham

When solving problems on a digital computer, continuous concepts are replaced by discrete versions. Some problems, such as those involving images on a computer screen, lead naturally to a discrete analogue involving integers. A classic example is the problem of drawing a plane curve using dots on a regularly spaced grid, such as on a bit-mapped display or a laser printer.

In the classic algorithm of Bresenham  the image of a curve is drawn using the dots closest to the curve. The geometry of such images is quite different from Euclidean geometry. Images of some parallel lines intersect, and images of some non-parallel lines intersect in more than one point.