Abstract: A set of pattern headers is used to replicate repeating patterns used in digitally-simulated halftone screens. The use of pattern headers is suited to digital processing systems which are most efficient when processing data having dimensions which are an integer power of two, yet permits generation of repeating patterns having dimensions which are other than an integer power of two. A complete repeating pattern is stored as a one-dimensional-array pattern header. The repeating pattern is generated from that pattern header by suitable shifting of the pattern header. The repeating pattern may be arbitrarily smaller than the pattern header and may, for example, comprise a binary bit pattern useful in driving a binary rendering device or a pattern of integer values representing tonal intensities of the digitally-simulated halftone screen useful in driving a variable-dot-size rendering device.

Abstract: Graphic plotting network methods and apparatus are disclosed for connecting one or more video signal sources, such as computer workstations and/or RGB dameras, to a single plotter. In a preferred embodiment, a video chain unit (VCU) is connected to each of the sources for receiving analog video and/or digital serial and/or digital parallel information, and the VCUs are interconnected in series with one another and with a video processing unit (VPU) which is in turn connected to the plotter. The interconnection is made in series such that any VCU may communicate with the VPU even if other VCUs in the chain are powered off and such that the VPU (and the plotter) can be placed anywhere in the chain. Each VCU has a set of switches for setting the plot parameters, for acquiring a plot, for repeating a plot, and for aborting a plot in process, and an indicator to show when the plotter is ready to acquire a plot.