Skip to main content

Irrational Halftoning for Electronic Registration

Buy Article:

$20.00 plus tax (Refund Policy)


As xerography moves to intercept offset printing, image quality becomes a key ingredient of success. Classic halftoning methods, which generally deliver good, low noise halftone dots, have fixed positions in the scan field that hinder several possible improvements to these printing systems.

First, exact halftone frequencies and angles would result if dot positions could be adjusted with arbitrary precision. This would improve the design of screen-sets that limit or reduce multiseparation moiré, or allow screen-sets that exhibit the classic rosette structure associated with offset printing.

Second, electronic registration systems could emerge if the halftone dot positions could be adjusted in response to actuation commands from the printer. Such systems would automatically compensate for mechanical distortions caused by bent mirrors, elliptical rollers, and tandem color print stations, for instance, and thus save manufacturing costs for the mechanical system.

Normally, the dot positions are fixed to small integer offsets (the angle corresponds to a “rational tangent”) in the scan field, thus preventing the occurrence of single separation moiré. When fractional dot positions are allowed (irrational tangent), moiré can result. Thus, if the moiré problem can be eliminated for irrational halftoning, the frequency and angle restrictions associated with rational tangent halftoning disappear.

I will present one solution to this problem that subsamples a halftone cluster function stored in a look-up table to produce reduced moiré separations while printing. Halftone dot locations are computed by hardware, and dot cluster shapes typically do not repeat. I will show a simulation of a three-separation image printed on a 600 spi digital printer that uses irrational offsets (m30°, c75°, and k45°) designed to produce a classic rosette structure. I will also show a simulation of these same dots being electronically registered, or warped.

Document Type: Research Article

Publication date: January 1, 2001

More about this publication?
  • For more than 25 years, NIP has been the leading forum for discussion of advances and new directions in non-impact and digital printing technologies. A comprehensive, industry-wide conference, this meeting includes all aspects of the hardware, materials, software, images, and applications associated with digital printing systems, including drop-on-demand ink jet, wide format ink jet, desktop and continuous ink jet, toner-based electrophotographic printers, production digital printing systems, and thermal printing systems, as well as the engineering capability, optimization, and science involved in these fields.

    Since 2005, NIP has been held in conjunction with the Digital Fabrication Conference.

  • Information for Authors
  • Submit a Paper
  • Subscribe to this Title
  • Membership Information
  • Terms & Conditions
  • Ingenta Connect is not responsible for the content or availability of external websites

Access Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Partial Open Access Content
Partial Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content
Cookie Policy
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more