Optimal image encoding for hard copy production and method of its efficiency estimation

Abstract

Unlike in a soft copy generating, the multilevel pictorial data are, after capturing by camera or scanner, once again encoded in prepress to get the output signal governing the halftone printing in bi-level, “ink – no ink” fashion. Criteria of such encoding optimization are comprised in the transfer through physical plate making and press communication channel onto a print with as much as possible of original image data perceivable for a viewer. It undermines the pro.viding of mutual conformity for parameters of a source image and channel, as well as for properties of an output print and vision. On the background of the screening developments overview for the last half a century, the paper presents: discussion of tone spatial dispersion in halftoning and accompanying contour and fine detail distortion; such distortion corrections and the method of quantitative estimation of their efficiency; principles of an image optimal encoding in prepress and their implementation in the High Definition Halftone Printing (HDHP); including results of testing and promotion issues of its practical application; and disclosed approach potential with the spatial dispersion adaptive to an arbitrary contour. Samples of test images and fragmentary photographs from illustrative print trails and jobs using HDHP are also presented. On this basis, the paper pretends to disclose some mainstream aspects bypassed in the most of other publications on halftoning.