Incremental line compaction

Raster devices, such as digital plotters, CRT or plasma panel displays, and matrix or ink jet printers, represent 'straight' lines in quantized fashion as a sequence of unit axial and unit diagonal steps. Dichotomous run lengths and periodic repetitive patterns in these incremental or digital lines provide a basis by which the step sequences for quantized lines can be treated in compressed form for storage or transmission. Earnshaw recently published a paper describing an investigation of two compaction alternatives encoding either run lengths or repeated patterns. This paper describes a simple algorithm to incorporate both run length and repeated pattern encoding for step sequence compaction. Also illustrated is the similarity in form of the repetitive loop used to generate either runs or single steps and either full lines or periodic patterns; initial parameter values differ, but the subsequent iterative process is identical. © 1982 The British Computer Society.