New screening/halftoning technology

• Improved algorithms for determining the angles and frequencies used for halftone screens. The improvements fall into two primary categories: general improvements, and improvements specific to color separations.
• General improvements: (1) The new algorithms yield a 10% improvement in the speed of the setscreen and image operators; (2) Earlier version of PostScript software could produce halftone screens only for certain angle and frequency combinations. Enough of these combinations were available so that any requested screen could be fairly well approximated by one of the available angle and frequency combinations. In contrast, the improved halftoning algorithms can provide as much as a ten-fold increase in the number of angle-frequency combinations that are available, depending on the device resolution and the available memory. Benefits: Increased performance and higher quality halftone screens.
• Improvements specific to color separations: An additional feature is available that enables PostScript software to generate extremely accurate screen angles and frequencies. The screens produced by this method can achieve an angular accuracy of within 05 degrees or better, depending on such parameters as exact screen angle requested, device resolution, and memory available for use by the algorithm. Benefits: Extremely high-quality color separations that approach the quality that previously was available only from high-end, color electronic pre-press systems.