ScaleAbilities (Sharon, MA) has received a U.S. patent for its new screening and compensation method designed specifically for multiple gray-level digital printers and presses. Multiple Phase Screening (MPS) provides both higher print quality as well as more robust compensation for those digital inkjet printheads having grayscale or “variable-dot” capabilities. Compared to alternatives, MPS claims the following advantages:
- Multiple increase in the number of screened tone levels for smoother blends
- Lower visible screening noise for improved photographic quality
- Elimination of flat-tone contour artifacts that are visually jarring
- Easier and more accurate compensation for special papers and difficult printing conditions
According to inventor Mitch Bogart, the system provides printer manufacturers with additional flexibilities. MPS eliminates the design constraint requiring gray levels to be equally spaced, is applicable for printers having any number of gray levels, and works with virtually every method of halftoning – especially non-dithered, non-correlated ones required for practical and stable sequential ink printing.
Bogart describes the system as a “divide-and-conquer” approach. The printable tone range is first divided into sections, which are separately compensated and screened, before being re-combined for multi-bit output. Tone range sections are also shifted based on print measurements, providing accurate linearization. Finally, the tone range sections are also given adjustable overlapping. This eliminates “dead zone” artifacts, while also producing compensation that is less sensitive to changes. Though initially intended for production digital inkjet presses, MPS can also enhance specialty printing such as textile, direct-to-garment, wide-format and ceramic printing, the company added.
ScaleAbilities is currently seeking licensing inquiries from both rip and printer manufacturers. Licenses come with sample code for both error diffusion and threshold array screening, and include both CPU and GPU program examples.