Sub-dot phase modulation for computer to plate inkjet system

摘要

Printing masters are produced by use of an inkjet printing system. The smallest halftone dot size which can be printed by the inkjet printing system is larger than the size of a pixel of the recording grid defined by the addressability of the printing device. The error diffusion algorithm is especially adapted to make use of the high addressability of the recording system. Using a sub-dot phase modulated error diffusion halftoning algorithm allows for the distance between the halftone dots to be modulated in much smaller increments than the size of the halftone dots themselves. Results can be further improved by dynamically influencing the threshold value in the error diffusion algorithm in accordance with previous output quantisation determinations. Variable coverage percentage of the pixels can be taken into account. The method can be extended to multilevel systems.