Browse Prior Art Database

METHOD FOR PRINTING IMPROVED IMAGE QUALITY HALFTONES USING A HEXAGONAL GRID

IP.com Disclosure Number: IPCOM000027415D
Original Publication Date: 1996-Oct-31
Included in the Prior Art Database: 2004-Apr-07
Document File: 2 page(s) / 73K

Publishing Venue

Xerox Disclosure Journal

Abstract

Proposed is a method of printing improved image quality halftones using a hexagonal grid, including: scanning an input image at eight bits per pixel using rectangular sampling; interpolating the image from rectangular grid sample points; performing hexagonal halftoning algorithms; and delaying a video laser driving signal by one half of a pixel period when writing an interpolated line at print time.

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XEROX DISCLOSURE JOURNAL

METHOD FOR PRZNTING IMPROVED IMAGE QUALITY HALFTONES USING A HEXAGONAL GRID
Robert P. Loce
Michael S. Cianciosi

Proposed Classification
U. S. C1. 358/466 Int. C1. H04n 01/40

Proposed is a method of printing improved image quality halftones using a hexagonal grid, including: scanning an input image at eight bits per pixel using rectangular sampling; interpolating the image from rectangular grid sample points; performing hexagonal halftoning algorithms; and delaying a video laser driving signal by one half of a pixel period when writing an interpolated line at print time.

The proposed method is easily incorporated into existing laser printing technology. Circuitry required to enable the printing of hexagonal sampled halftones is based on established logic design practices. Hexagonal halftone algorithms are developed for Clustered Dot, Dispersed Dot, and Error Diffusion halftones.

The proposed method achieves improved image quality over traditional rectangularly sampled systems. One image quality improvement is an improvement in tone reproduction. Color halftoning is extended and is not limited to black and white. The hexagonal sampled halftones (having improved tone reproduction) are printed with the same screen visibility as the rectangularly sampled image. Conversely, hexagonally sampled halftone images can be printed with similar tone reproduction as rectangularly sampled halftone images, but with less visible screens. Fewer error diffus...