Does the Halftone Print Still Need a Photographic Quality?

摘要

Many patented screening techniques were brought to the market during the last decade as a challenge to the conventional ones. The "photographic quality" prevailed in their advertised advantages to indicate on a higher definition of prints thereby produced. However, for example, in FM and error diffusion screening the increase of spatial resolution is accompanied by the structural non-uniformity and loss of tone rendition. Lower printability has to be compensated by reduction the NSR of a printing system, i.e. by the use of a finer, hence costly, consumables and plate-ink-paper interaction. That resulted in poor practical implementation of these techniques in spite of their availability in the prepress software and equipment of the most vendors. To the contrary, resolution and sharpness are improved in the Adaptive Screening technology with no effect on the printability of a halftone structure. For the stationary image area it stays exactly the same as in a widely used conventional methods. At the same time, the halftone dots or the parts thereof no more exist at contour and fine detail and don't destroy the latter. As our experimental printing shows, the effect of an improvement is different for various kinds of jobs and printing conditions. So, this effect is to be discussed with taking into account: 1. the sampling factor (SF); 2. screen ruling value; 3. dot pattern geometry for the stationary image area.