Digital halftone rendering of a gray scale image with frequency dependent diagonal correlation
US5526438A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 28, 1994 |
| Grant date | Jun 11, 1996 |
| Priority date | — |
| Expiry date | Nov 28, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4051
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method of halftoning a digital gray scale image is disclosed that utilizes a point by point thresholding comparison to a novel diagonal correlation dither matrix. The new dither matrix forces diagonal correlation of adjacent dots in the output image while maximizing dispersion of dots, thereby producing visually unobtrusive output dot patterns. The matrix is generated according to a spatial domain cost function that determines a cost value for each candidate pixel based on respective radial distances and relative angles between a candidate pixel and the ON pixels in the matrix such that unit diagonals are favored over placement of vertically or horizontally adjacent dots.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.